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+Mecca, officially Makkah al-Mukarramah (Arabic: مكة المكرمة‎, romanized: Makkat al-Mukarramah, lit. 'Makkah the Noble') and commonly shortened to Makkah,[a] is the holiest city in Islam and the capital of the Makkah Province of Saudi Arabia.[2] The city is located 70 km (43 mi) inland from Jeddah on the Red Sea, in a narrow valley 277 m (909 ft) above sea level. Its last recorded population was 1,578,722 in 2015.[3] estimated metro population in 2020 is 2.042 million, making it the third-most populated city in the kingdom. Pilgrims more than triple this number every year during the Ḥajj pilgrimage, observed in the twelfth Hijri month of Dhūl-Ḥijjah.
+
+Mecca is the birthplace of Muhammad. The Hira cave located atop the Jabal al-Nur ("Mountain of Light") is located just outside the city and is the location where Muslims believe the Qur'an was first revealed to Muhammad.[4][5] Visiting Mecca for the Hajj is an obligation upon all able Muslims. The Great Mosque of Mecca, known as the Masjid al-Haram is home to the Ka'bah, believed by Muslims to have been built by Abraham and Ishmael, is one of Islam's holiest sites and the direction of prayer for all Muslims (qibla), cementing Mecca's significance in Islam.[6]
+
+Muslim rulers from in and around the region long tried to take the city and keep it in their control, and thus, much like most of the Hejaz region, the city has seen several regime changes, which owes to its rich history. The city was finally conquered in the Saudi conquest of Hejaz by Ibn Saud and his allies in 1925. Since then. Mecca has seen a tremendous expansion in size and infrastructure, with newer, modern buildings such as the Abraj Al Bait, the world's fourth-tallest building and third-largest by floor area, towering over the Great Mosque. The Saudi government has also carried out a destruction of several historical structures and archaeological sites, such as the Ajyad Fortress.[7][8][9] Non-Muslims are strictly prohibited from entering the city.[10][11]
+
+Muslims from around the world visit the city, not only for the Hajj and Umrah pilgrimages, but also as tourists to visit regional landmarks such as the 'Aisha Mosque (Masjid 'Aisha) and the sites visited by pilgrims in the Hajj and 'Umrah. Mecca is now home to two of the most expensive buildings in the world, the Masjid al-Haram, valued at 100 billion US dollars and the Abraj al-Bait complex, valued at 15 billion US dollars.
+
+Mecca has been referred to by many names. As with many Arabic words, the etymology of Makkah is obscure.[12] Widely believed to be a synonym for Mecca, it is said to be more specifically the early name for the valley located therein, while Muslim scholars generally use it to refer to the sacred area of the city that immediately surrounds and includes the Ka'bah.[13][14]
+
+The Qur'an refers to the city as Bakkah in Surah Al Imran (3), verse 96,
+
+"Indeed the first House [of worship], established for mankind was that at Bakkah..."
+– Qur'an 3:96
+
+This is presumed to have been the name of the city at the time of Abraham (Ibrahim in Islamic tradition) and it is also transliterated as Baca, Baka, Bakah, Bakka, Becca, Bekka, among others.[15][16][17]
+
+In South Arabic, the language in use in the southern portion of the Arabian Peninsula at the time of Muhammad, the b and m were interchangeable. This is presumed to have been the origin of the current form of the name. "Makkah" is the official transliteration used by the Saudi government and is closer to the Arabic pronunciation.[18][19] The government adopted Makkah as the official spelling in the 1980s, but is not universally known or used worldwide.[18] The full official name is Makkah al-Mukarramah (Arabic: مكة المكرمة‎, romanized: Makkat al-Mukarramah, lit. 'Makkah the Honored').[18] "Makkah" is used to refer to the city in the Qur'an in Surah Al-Fath (48), verse 24.[12][20]
+
+The word "Mecca" in English has come to be used to refer to any place that draws large numbers of people, and because of this some English-speaking Muslims have come to regard the use of this spelling for the city as offensive.[18]  Mecca is the familiar form of the English transliteration for the Arabic name of the city,
+
+The consensus in academic scholarship is that "Macoraba", the place mentioned in Arabia Felix by Claudius Ptolemy, is Mecca. Many etymologies have been proposed but the most suitable one is that it is derived from the Old South Arabian root "M-K-R-B" which means temple.[21][22]
+
+Another name used for Mecca in the Qur'an is at 6:92 where it is called Umm al-Qurā[23] (أُمّ ٱلْقُرَى, meaning "Mother of all Settlements".[20] The city has been called several other names in both the Qur'an and ahadith. Another name used historically for Mecca is Tihāmah.[24] According to Arab and Islamic tradition, another name for Mecca, Fārān, is synonymous with the Desert of Paran mentioned in the Old Testament at Genesis 21:21.[25] Arab and Islamic tradition holds that the wilderness of Paran, broadly speaking, is the Tihamah coastal plain and the site where Ishmael settled was Mecca.[25] Yaqut al-Hamawi, the 12th century Syrian geographer, wrote that Fārān was "an arabized Hebrew word, one of the names of Mecca mentioned in the Torah."[26]
+
+In 2010, Mecca and the surrounding area became an important site for paleontology with respect to primate evolution, with the discovery of a Saadanius fossil. Saadanius is considered to be a primate closely related to the common ancestor of the Old World monkeys and apes. The fossil habitat, near what is now the Red Sea in western Saudi Arabia, was a damp forest area between 28 million and 29 million years ago.[27] Paleontologists involved in the research hope to find further fossils in the area.[28]
+
+The early history of Mecca is still largely disputed, as there are no unambiguous reference to it in ancient literature prior to the rise of Islam[29] and no architecture from the time of Mohammed.[30]The Roman Empire took control of part of the Hejaz in 106 CE,[31] ruling cities such as Hegra (now known as Mada'in Saleh), located around 800 km (500 mi) north of Mecca. Even though detailed descriptions of Western Arabia were established by the Romans, such as by Procopius, there are no references of a pilgrimage and trading outpost such as Mecca.[32]
+
+The Greek historian Diodorus Siculus writes about Arabia in his work Bibliotheca historica, describing a holy shrine: "And a temple has been set up there, which is very holy and exceedingly revered by all Arabians".[33] Claims have been made this could be a reference to the Ka'bah in Mecca. However, the geographic location Diodorus describes is located in northwest Arabia, around the area of Leuke Kome, closer to Petra and within the former Nabataean Kingdom and Roman province of Arabia Petraea.[34][35][36]
+
+Ptolemy lists the names of 50 cities in Arabia, one going by the name of "Macoraba". There has been speculation since 1646 that this could be a reference to Mecca, but many scholars see no compelling explanation to link the two names.[37] Bowersock favors the identity of the former, with his theory being that "Macoraba" is the word "Makkah" followed by the aggrandizing Aramaic adjective rabb (great). The Roman historian Ammianus Marcellinus also enumerated many cities of Western Arabia, most of whom can be identified. According to Bowersock, he did mention Mecca as "Geapolis" or "Hierapolis", the latter one meaning "holy city", referring to the sanctuary of the Ka'bah, well known already in pagan times.[38] Patricia Crone, from the Revisionist school of Islamic studies on the other hand, writes that "the plain truth is that the name Macoraba has nothing to do with that of Mecca [...] if Ptolemy mentions Mecca at all, he calls it Moka, a town in Arabia Petraea"[39] (in northwest Arabia near present-day Petra).
+
+The first direct reference to Mecca in external literature occurs in 741 CE, in the Byzantine-Arab Chronicle, though here the author places it in Mesopotamia rather than the Hejaz.[32] Given the inhospitable environment,[40] and lack of historical references in Roman, Persian and Indian sources, historians including Patricia Crone and Tom Holland have cast doubt on the claim that Mecca was a major historical trading outpost.[40][41] However, other scholars such as Glen W. Bowersock disagree and assert that Mecca was a major trading outpost.[42][43][44]
+
+Mecca is mentioned in the following early Qur'anic manuscripts:
+
+In the Islamic view, the beginnings of Mecca are attributed to the Biblical figures, Abraham, Hagar and Ishmael. The civilization of Mecca is believed to have started after Ibrāhīm (Abraham) left his son Ismāʿīl (Ishmael) and wife Hājar (Hagar) in the valley at Allah's command. Some people from the Yemeni tribe of Jurhum settled with them, and Isma'il reportedly married two women, one after divorcing the first, on Ibrahim's advice. At least one man of the Jurhum helped Ismāʿīl and his father to construct or according to Islamic narratives, reconstruct, the Ka'bah ('Cube'),[45][13][46] which would have social, religious, political and historical implications for the site and region.[47][48][49][48]
+
+Muslims see the mention of a pilgrimage at the Valley of Baca in the Old Testament chapter Psalm 84:3–6 as a reference to Mecca, similar to the Qur'an at Surah 3:96.[13] In the Sharḥ al-Asāṭīr, a commentary on the Samaritan midrashic chronology of the Patriarchs, of unknown date but probably composed in the 10th century CE, it is claimed that Mecca was built by the sons of Nebaioth, the eldest son of Ismāʿīl orIshmael.[50][51][52]
+
+Some Thamudic inscriptions which were discovered in the south Jordan contained names of some individuals such as ʿAbd Mekkat (عَبْد مَكَّة, "Servant of Mecca").[53]
+
+There were also some other inscriptions which contained personal names such as Makki (مَكِّي, "Meccan"), but Jawwad Ali from the University of Baghdad suggested that there's also a probability of a tribe named "Makkah".[54]
+
+Some time in the 5th century, the Ka'bah was a place of worship for the deities of Arabia's pagan tribes. Mecca's most important pagan deity was Hubal, which had been placed there by the ruling Quraish tribe.[55][56] and remained until the Conquest of Mecca by Muhammad. In the 5th century, the Quraish took control of Mecca, and became skilled merchants and traders. In the 6th century, they joined the lucrative spice trade, since battles elsewhere were diverting trade routes from dangerous sea routes to more secure overland routes. The Byzantine Empire had previously controlled the Red Sea, but piracy had been increasing. Another previous route that ran through the Persian Gulf via the Tigris and Euphrates rivers was also being threatened by exploitations from the Sassanid Empire, and was being disrupted by the Lakhmids, the Ghassanids, and the Roman–Persian Wars. Mecca's prominence as a trading center also surpassed the cities of Petra and Palmyra.[57][58] The Sassanids however did not always pose a threat to Mecca, as in 575 CE they protected it from an Yemeni invasion, led by its Christian leader Abraha. The tribes of southern Arabia asked the Persian king Khosrau I for aid, in response to which he came south to Arabia with foot-soldiers and a fleet of ships near Mecca.[59]
+
+By the middle of the 6th century, there were three major settlements in northern Arabia, all along the south-western coast that borders the Red Sea, in a habitable region between the sea and the Hejaz mountains to the east. Although the area around Mecca was completely barren, it was the wealthiest of the three settlements with abundant water from the renowned Zamzam Well and a position at the crossroads of major caravan routes.[60]
+
+The harsh conditions and terrain of the Arabian peninsula meant a near-constant state of conflict between the local tribes, but once a year they would declare a truce and converge upon Mecca in an annual pilgrimage. Up to the 7th century, this journey was intended for religious reasons by the pagan Arabs to pay homage to their shrine, and to drink Zamzam. However, it was also the time each year that disputes would be arbitrated, debts would be resolved, and trading would occur at Meccan fairs. These annual events gave the tribes a sense of common identity and made Mecca an important focus for the peninsula.[61]
+
+The "Year of the Elephant" is the name in Islamic history for the year approximately equating to 550-552 CE, when, according to Islamic sources such as Ibn Ishaq, Abraha descended upon Mecca, riding an elephant, with a large army after building a cathedral at San'aa, named al-Qullays in honor of the Negus of Axum. It gained widespread fame, even gaining attention from the Byzantine Empire.[62] Abraha attempted to divert the pilgrimage of the Arabs from the Ka'bah to al-Qullays, effectively converting them to Christianity. According to Islamic tradition, this was the year of Muhammad's birth.[62] Abraha allegedly sent a messenger named Muhammad ibn Khuza'i to Mecca and Tihamah with a message that al-Qullays was both much better than other houses of worship and purer, having not been defiled by the housing of idols.[62] When Muhammad ibn Khuza'i got as far as the land of Kinana, the people of the lowland, knowing what he had come for, sent a man of Hudhayl called ʿUrwa bin Hayyad al-Milasi, who shot him with an arrow, killing him. His brother Qays who was with him, fled to Abraha and told him the news, which increased his rage and fury and he swore to raid the Kinana tribe and destroy the Ka'bah. Ibn Ishaq further states that one of the men of the Quraysh tribe was angered by this, and going to Sana'a, entering the church at night and defiling it; widely assumed to have done so by defecating in it.[63][64]
+
+Abraha marched upon the Ka'bah with a large army, which included one or more war elephants, intending to demolish it. When news of the advance of his army came, the Arab tribes of Quraysh, Kinanah, Khuza'a and Hudhayl united in the defense of the Ka'bah and the city. A man from the Himyarite Kingdom was sent by Abraha to advise them that Abraha only wished to demolish the Ka'bah and if they resisted, they would be crushed. Abdul Muttalib told the Meccans to seek refuge in the hills while he and some members of the Quraysh remained within the precincts of the Kaaba. Abraha sent a dispatch inviting Abdul-Muttalib to meet with Abraha and discuss matters. When Abdul-Muttalib left the meeting he was heard saying,
+
+"The Owner of this House is its Defender, and I am sure he will save it from the attack of the adversaries and will not dishonor the servants of His House."
+
+Abraha eventually attacked Mecca. However, the lead elephant, known as Mahmud,[65] is said to have stopped at the boundary around Mecca and refused to enter. It has been theorized that an epidemic such as by smallpox could have caused such a failed invasion of Mecca.[66] The reference to the story in Quran is rather short. According to the 115th Surah of the Qur'an, Al-Fil, the next day, a dark cloud of small birds sent by Allah appeared. The birds carried small rocks in their beaks, and bombarded the Ethiopian forces and smashed them to a state like that of eaten straw.[67]
+
+Camel caravans, said to have first been used by Muhammad's great-grandfather, were a major part of Mecca's bustling economy. Alliances were struck between the merchants in Mecca and the local nomadic tribes, who would bring goods – leather, livestock, and metals mined in the local mountains – to Mecca to be loaded on the caravans and carried to cities in Shaam and Iraq.[68] Historical accounts also provide some indication that goods from other continents may also have flowed through Mecca. Goods from Africa and the Far East passed through en route to Syria including spices, leather, medicine, cloth, and slaves; in return Mecca received money, weapons, cereals and wine, which in turn were distributed throughout Arabia. The Meccans signed treaties with both the Byzantines and the Bedouins, and negotiated safe passages for caravans, giving them water and pasture rights. Mecca became the center of a loose confederation of client tribes, which included those of the Banu Tamim. Other regional powers such as the Abyssinians, Ghassanids, and Lakhmids were in decline leaving Meccan trade to be the primary binding force in Arabia in the late 6th century.[61]
+
+Muhammad was born in Mecca in 570, and thus Islam has been inextricably linked with it ever since. He was born in a minor faction, the Banu Hashim, of the ruling Quraysh tribe. It was in Mecca, in the nearby mountain cave of Hira on Jabal al-Nour, that, according to Islamic tradition, Muhammad began receiving divine revelations from God through the archangel Jibreel in 610 AD. Advocating his form of Abrahamic monotheism against Meccan paganism, and after enduring persecution from the pagan tribes for 13 years, Muhammad emigrated to Medina (hijrah) in 622 with his companions, the Muhajirun, to Yathrib (later renamed Madinah). The conflict between the Quraysh and the Muslims is accepted to have begun at this point. Overall, Meccan efforts to annihilate Islam failed and proved to be costly and unsuccessful. During the Battle of the Trench in 627, the combined armies of Arabia were unable to defeat Muhammad's forces.[69]
+In 628, Muhammad and his followers wanted to enter Mecca for pilgrimage, but were blocked by the Quraysh. Subsequently, Muslims and Meccans entered into the Treaty of Hudaybiyyah, whereby the Quraysh and their allies promised to cease fighting Muslims and their allies and promised that Muslims would be allowed into the city to perform the pilgrimage the following year. It was meant to be a ceasefire for 10 years; however, just two years later, the Banu Bakr, allies of the Quraish, violated the truce by slaughtering a group of the Banu Khuza'ah, allies of the Muslims. Muhammad and his companions, now 10,000 strong, marched into Mecca and conquered the city. The pagan imagery was destroyed by Muhammad's followers and the location Islamized and rededicated to the worship of Allah alone. Mecca was declared the holiest site in Islam ordaining it as the center of Muslim pilgrimage (Hajj), one of the faith's Five Pillars.
+
+Muhammad then returned to Medina, after assigning 'Akib ibn Usaid as governor of the city. His other activities in Arabia led to the unification of the peninsula under the banner of Islam.[57][69] Muhammad died in 632. Within the next few hundred years, stretched from North Africa into Asia and parts of Europe. As the Islamic realm grew, Mecca continued to attract pilgrims from all across the Muslim world and beyond, as Muslims came to perform the annual Hajj pilgrimage. Mecca also attracted a year-round population of scholars, pious Muslims who wished to live close to the Kaaba, and local inhabitants who served the pilgrims. Due to the difficulty and expense of the Hajj, pilgrims arrived by boat at Jeddah, and came overland, or joined the annual caravans from Syria or Iraq.
+
+Mecca was never the capital of any of the Islamic states. Muslim rulers did contribute to its upkeep, such as during the reigns of 'Umar (r. 634–644 CE) and 'Uthman ibn Affan (r. 644–656 CE) when concerns of flooding caused the caliphs to bring in Christian engineers to build barrages in the low-lying quarters and construct dykes and embankments to protect the area round the Kaaba.[57]
+
+Muhammad's return to Medina shifted the focus away from Mecca and later even further away when 'Ali, the fourth caliph, took power chose Kufa as his capital. The Umayyad Caliphate moved the capital to Damascus in Syria and the Abbasid Caliphate to Baghdad, in modern-day Iraq, which remained the center of the Islamic Empire for nearly 500 years. Mecca re-entered Islamic political history during the Second Fitna, when it was held by Abdullah ibn az-Zubayr and the Zubayrids. The city was twice besieged by the Umayyads, in 683 and 692 and for some time thereafter, the city figured little in politics, remaining a city of devotion and scholarship governed by various other factions. In 930, Mecca was attacked and sacked by Qarmatians, a millenarian Shi'a Isma'ili Muslim sect led by Abū-Tāhir Al-Jannābī and centered in eastern Arabia.[70] The Black Death pandemic hit Mecca in 1349.[71]
+
+Makkah, ca. 1718 CE
+
+Makkah, ca. 1778 CE
+
+Makkah, in the 1880s
+
+Makkah in 1910
+
+Pilgrims surround the Ka'bah in 1910
+
+One of the most famous travelers to Mecca in the 14th century was Moroccan scholar and traveler, Ibn Battuta. In his rihla (account), he provides a vast description of the city. Around the year 1327 CE or 729 AH, Ibn Battuta arrived at the holy city. Immediately, he says, it felt like a holy sanctuary and thus. he started the rites of the pilgrimage. He remained in Mecca for three years and left in 1330 CE. During his second year in the holy city, he says his caravan arrived "with a great quantity of alms for the support of those who were staying in Mecca and Medina". While in Mecca, prayers were made for (not to) the King of Iraq and also for Salaheddin al-Ayyubi, Sultan of Egypt and Syria at the Ka'bah. Battuta says the Ka'bah was large, but was destroyed and rebuilt smaller than the original and that it contained images of angels and prophets including Jesus, his mother Mary and many others. Battuta describes the Ka'bah as an important part of Mecca due to the fact that many people make the pilgrimage to it. Battuta describes the people of the city as being humble and kind, and also willing to give a part of everything they had to someone who had nothing. The inhabitants of Mecca and the village itself, he says, were very clean. There was also a sense of elegance to the village.[72]
+
+In 1517, the then Sharif of Mecca, Barakat bin Muhammad, acknowledged the supremacy of the Ottoman Caliph but retained a great degree of local autonomy.[73] In 1803 the city was captured by the First Saudi State,[74] which held Mecca until 1813. destroying some of the historic tombs and domes in and around the city. The Ottomans assigned the task of bringing Mecca back under Ottoman control to their powerful Khedive (viceroy) and Wali of Egypt, Muhammad Ali Pasha. Muhammad Ali Pasha successfully returned Mecca to Ottoman control in 1813. In 1818, the Saud were defeated again but survived and founded the Second Saudi State that lasted until 1891 and led on to the present country of Saudi Arabia. In 1853, Sir Richard Francis Burton undertook the Muslim pilgrimage to Mecca and Medina disguised as a Muslim. Although Burton was certainly not the first non-Muslim European to make the Hajj (Ludovico di Varthema did this in 1503),[75] his pilgrimage remains one of the most famous and documented of modern times. Mecca was regularly hit by cholera outbreaks. Between 1830 and 1930, cholera broke out among pilgrims at Mecca 27 times.[76]
+
+In World War I, the Ottoman Empire was at war with Britain and its allies. It had successfully repulsed an attack on Istanbul in the Gallipoli Campaign and on Baghdad in the Siege of Kut. The British agent T.E. Lawrence conspired with the Ottoman governor, Hussain bin Ali, the Sharif of Mecca to revolt against the Ottoman Empire and it was the first city captured by his forces in the 1916 Battle of Mecca. Sharif's revolt proved a turning point of the war on the eastern front. Hussein declared a new state, the Kingdom of Hejaz, declaring himself the Sharif of the state and Mecca his capital. News reports in November 1916 via contact in Cairo with returning Hajj pilgrims, stated that with the Ottoman Turkish authorities gone, the Hajj of 1916 was free of the previous massive extortion and monetary demands made by the Turks who were agents of the Ottoman government.[77]
+
+Following the 1924 Battle of Mecca, the Sharif of Mecca was overthrown by the Saud family, and Mecca was incorporated into Saudi Arabia.[78] Under Saudi rule, much of the historic city has been demolished as a result of the Saudi government fearing these sites might become sites of association in worship beside Allah (shirk). The city has been expanded to include several towns previously considered to be separate from the holy city and now is just a few kilometers outside the main sites of the Hajj, Mina, Muzdalifah and Arafat. Mecca is not served by any airport, due to concerns about the city's safety. It is instead served by the King Abdulaziz International Airport in Jeddah (approx. 70 km away) internationally and the Ta'if Regional Airport (approx. 120 km away) for domestic flights.
+
+The city today is at the junction of the two most important highways in all of the Saudi Arabian highway system, Highway 40, which connects the city to Jeddah in the west and the capital, Riyadh and Dammam in the east and Highway 15, which connects it to Medina, Tabuk and onward to Jordan in the north and Abha and Jizan in the south. The Ottomans had planned to extend their railway network to the holy city, but were forced to abandon this plan due to their partaking in the First World War. This plan was later carried out by the Saudi government, which connected the two holy cities of Medina and Mecca with the modern Haramain high-speed railway system which runs at 300 km/h (190 mph) and connects the two cities via Jeddah, King Abdulaziz International Airport and King Abdullah Economic City near Rabigh within two hours.
+
+The haram area of Mecca, in which the entry of non-Muslims is forbidden, is much larger than that of Medina.
+
+On 20 November 1979, two hundred armed dissidents led by Juhayman al-Otaibi, seized the Grand Mosque, claiming the Saudi royal family no longer represented pure Islam and that the Masjid al-Haram and the Ka'bah, must be held by those of true faith. The rebels seized tens of thousands of pilgrims as hostages and barricaded themselves in the mosque. The siege lasted two weeks, and resulted in several hundred deaths and significant damage to the shrine, especially the Safa-Marwah gallery. A multinational force was finally able to retake the mosque from the dissidents.[79] Since then, the Grand Mosque has been expanded several times, with many other expansions being undertaken in the present-day.
+
+Under Saudi rule, it has been estimated that since 1985, about 95% of Mecca's historic buildings, most over a thousand years old, have been demolished.[7][80] It has been reported that there are now fewer than 20 structures remaining in Mecca that date back to the time of Muhammad. Some important buildings that have been destroyed include the house of Khadijah, the wife of Muhammad, the house of Abu Bakr, Muhammad's birthplace and the Ottoman-era Ajyad Fortress.[81] The reason for much of the destruction of historic buildings has been for the construction of hotels, apartments, parking lots, and other infrastructure facilities for Hajj pilgrims.[80]
+
+Mecca has been the site of several incidents and failures of crowd control because of the large numbers of people who come to make the Hajj.[82][83][84] For example, on 2 July 1990, a pilgrimage to Mecca ended in tragedy when the ventilation system failed in a crowded pedestrian tunnel and 1,426 people were either suffocated or trampled to death in a stampede.[85] On 24 September 2015, 700 pilgrims were killed in a stampede at Mina during the stoning-the-Devil ritual at Jamarat.[86]
+
+Mecca is governed by the Makkah Regional Municipality, a municipal council of 14 locally elected members headed by the mayor (called Amin in Arabic) appointed by the Saudi government. As of May 2015[update], the mayor of the city is Dr. Osama bin Fadhel Al-Barr.[87][88] Mecca is the capital of the Makkah Province, which includes the neighboring cities of Jeddah and Ta'if, even though Jeddah is considerably larger in population compared to Mecca. The Provincial Governor of the province from 16 May 2007 is Prince Khalid bin Faisal Al Saud was appointed as the new governor.[89]
+
+Mecca holds an important place in Islam and is the holiest city in all branches of the religion. The city derives its importance from the role it plays in the Hajj and 'Umrah.
+
+The Masjid al-Haram is the largest mosque in the world and the most expensive single building in the entire world, valued at 100 billion US dollars, as of 2020.[90] It is the site of two of the most important rites of both the Hajj and of the Umrah, the circumambulation around the Ka'bah (tawaf) and the walking between the two mounts of Safa and Marwa (sa'ee). The masjid is also the site of the Zamzam Well. According to Islamic tradition, a prayer in the masjid is equal to 100,000 prayers in any other masjid around the world.[91]
+
+There is a difference of opinion between Islamic scholars upon who first built the Ka'bah, some believe it was built by the angels while others believe it was built by Adam. Regardless, it was built several times before reaching its current state, the most famous of these renovations being the one by Abraham (Ibrahim in Islamic tradition). The Ka'bah is also the common direction of prayer (qibla) for all Muslims. The surface surrounding the Ka'bah on which Muslims circumambulate it is known as the Mataf.
+
+The Black Stone is a stone, considered by scientists to be a meteorite or of similar origin and believed by Muslims to be of divine origin. It is set in a corner of the Ka'bah and it is Sunnah to touch and kiss the stone. The area around the stone is generally always crowded and guarded by policemen to ensure the pilgrims' safety.
+
+This is a stone which Muslims believe Abraham stood on to build the higher parts of the Ka'bah. It contains two footprints that are comparatively larger than average modern-day human feet. The stone is raised and housed in a golden hexagonal chamber beside the Ka'bah on the Mataf plate.
+
+Muslims believe that in the divine revelation to Muhammad, the Qur'an, Allah describes the mountains of Safa and Marwah as symbols of his divinity. Walking between the two mountains seven times, 4 times from Safa to Marwah and 3 times from Marwah interchangeably, is considered a mandatory pillar (rukn) of 'Umrah.
+
+The Hajj pilgrimage, also called the greater pilgrimage, attracts millions of Muslims from all over the world and almost triples Mecca's population for one week in the twelfth and final Islamic month of Dhu al-Hijjah. In 2019, the Hajj attracted 2,489,406 pilgrims to the holy city.[92] The 'Umrah, or the lesser pilgrimage, can be done at anytime during the year.  Every adult, healthy Muslim who has the financial and physical capacity to travel to Mecca must perform the Hajj at least once in a lifetime. Umrah, the lesser pilgrimage, is not obligatory, but is recommended in the Quran.[93]
+
+In addition to the Masjid al-Haram, pilgrims also must visit the nearby towns of Mina/Muna, Muzdalifah and 'Arafah/'Arafat for varying rituals that are part of the Hajj.
+
+This is a mountain believed by Muslims to have been the place where Muhammad spent his time away from the bustling city of Mecca in seclusion.[94][95] The mountain is located on the eastern entrance of the city and is the highest point in the city at 642 meters (2,106 feet).
+
+This is the place where Muslims believe Muhammad received the first revelation from Allah through the archangel Gabriel (Jibril in Islamic tradition) at the age of 40.[94][95]
+
+The Mecca Gate, known popularly as the Qur'an Gate, on the western entrance of the city of Mecca, or from Jeddah. Located on Highway 40, it marks the boundary of the Haram area where non-Muslims are prohibited from entering. The gate was designed in 1979 by an Egyptian architect, Samir Elabd, for the architectural firm IDEA Center. The structure is that of a book, representing the Quran, sitting on a rehal, or bookrest.[96]
+
+Mecca is located in the Hejaz region, a 200 km (124 mi) wide strip of mountains separating the Nafud desert from the Red Sea. The city is situated in a valley with the same name around 70 km (44 mi) west of the port city of Jeddah. Mecca is one of the lowest cities in elevation in the Hejaz region, located at an elevation of 277 m (909 ft) above sea level at 21º23' north latitude and 39º51' east longitude. Mecca is divided into 34 districts.
+
+The city centers on the al-Haram area, which contains the Masjid al-Haram. The area around the mosque is the old city and contains the most famous district of Mecca, Ajyad. The main street that runs to al-Haram is the Ibrahim al-Khalil Street, named after Ibrahim. Traditional, historical homes built of local rock, two to three stories long are still present within the city's central area, within view of modern hotels and shopping complexes. The total area of modern Mecca today is over 1,200 km2 (460 sq mi).[97]
+
+Mecca is at an elevation of 277 m (909 ft) above sea level, and approximately 70 km (44 mi) inland from the Red Sea.[60] It is one of the lowest in the Hejaz region.
+
+The city center lies in a corridor between mountains, which is often called the "Hollow of Mecca". The area contains the valley of al-Taneem, the valley of Bakkah and the valley of Abqar.[57][98] This mountainous location has defined the contemporary expansion of the city.
+
+In pre-modern Mecca, the city used a few chief sources of water. The first were local wells, such as the Zamzam Well, that produced generally brackish water. The second source was the spring of 'Ayn Zubaydah (Spring of Zubaydah). The sources of this spring are the mountains of Jabal Sa'd and Jabal Kabkāb, which are a few kilometers east of 'Arafah/'Arafat or about 20 km (12 mi) southeast of Mecca. Water was transported from it using underground channels. A very sporadic third source was rainfall which was stored by the people in small reservoirs or cisterns. The rainfall, scant as it is, also presents the threat of flooding and has been a danger since earliest times. According to al-Kurdī, there have been 89 floods by 1965. In the last century, the most severe flood was that of 1942. Since then, dams have been built to ameliorate this problem.[98]
+
+Mecca features a hot desert climate (Köppen: BWh), in three different plant hardiness zones: 10, 11 and 12.[99] Like most Saudi Arabian cities, Mecca retains warm to hot temperatures even in winter, which can range from 19 °C (66 °F) at night to 30 °C (86 °F) in the afternoon, but also, very rarely, fall to zero and subzero temperatures. Summer temperatures are extremely hot and consistently break the 40 °C (104 °F) mark in the afternoon, dropping to 30 °C (86 °F) in the evening, but humidity remains relatively low, at 30–40%. Rain usually falls in Mecca in small amounts scattered between November and January, with heavy thunderstorms also common during the winter.
+
+The Meccan economy has been heavily dependent on the annual pilgrimage. Income generated from the Hajj, in fact, not only powers the Meccan economy but has historically had far-reaching effects on the economy of the entire Arabian Peninsula. The income was generated in a number of ways. One method was taxing the pilgrims. Taxes were especially increased during the Great Depression, and many of these taxes existed to as late as 1972. Another way the Hajj generates income is through services to pilgrims. For example, the Saudi flag carrier, Saudia, generates 12% of its income from the pilgrimage. Fares paid by pilgrims to reach Mecca by land also generate income; as do the hotels and lodging companies that house them.[98] The city takes in more than $100 million, while the Saudi government spends about $50 million on services for the Hajj. There are some industries and factories in the city, but Mecca no longer plays a major role in Saudi Arabia's economy, which is mainly based on oil exports.[102] The few industries operating in Mecca include textiles, furniture, and utensils. The majority of the economy is service-oriented.
+
+Nevertheless, many industries have been set up in Mecca. Various types of enterprises that have existed since 1970 in the city include corrugated iron manufacturing, copper extraction, carpentry, upholstery, bakeries, farming and banking.[98] The city has grown substantially in the 20th and 21st centuries, as the convenience and affordability of jet travel has increased the number of pilgrims participating in the Hajj. Thousands of Saudis are employed year-round to oversee the Hajj and staff the hotels and shops that cater to pilgrims; these workers in turn have increased the demand for housing and services. The city is now ringed by freeways, and contains shopping malls and skyscrapers.[103]
+
+Formal education started to be developed in the late Ottoman period continuing slowly into Hashemite times. The first major attempt to improve the situation was made by a Jeddah merchant, Muhammad ʿAlī Zaynal Riḍā, who founded the Madrasat al-Falāḥ in Mecca in 1911–12 that cost £400,000.[98] The school system in Mecca has many public and private schools for both males and females. As of 2005, there were 532 public and private schools for males and another 681 public and private schools for female students.[104] The medium of instruction in both public and private schools is Arabic with emphasis on English as a second language, but some private schools founded by foreign entities such as International schools use the English language for medium of instruction. Some of these are coeducational while other schools are not. For higher education, the city has only one university, Umm Al-Qura University, which was established in 1949 as a college and became a public university in 1979.
+
+Healthcare is provided by the Saudi government free-of-charge to all pilgrims. There are ten main hospitals in Mecca:[105]
+
+There are also many walk-in clinics available for both residents and pilgrims. Several temporary clinics are set up during the Hajj to tend to wounded pilgrims.
+
+In February 2020, Saudi Arabia temporarily banned foreigners from entering Mecca and Medina to mitigate the COVID-19 pandemic in the Kingdom.[106]
+
+Mecca's culture has been affected by the large number of pilgrims that arrive annually, and thus boasts a rich cultural heritage. As a result of the vast numbers of pilgrims coming to the city each year, Mecca has become by far the most diverse city in the Muslim world. In contrast to the rest of Saudi Arabia, and particularly Najd, Mecca has, according to The New York Times, become "a striking oasis of free thought and discussion and, also, of unlikely liberalism as Meccans see themselves as a bulwark against the creeping extremism that has overtaken much Islamic debate".[9]
+
+Al Baik, a local fast-food chain is very popular among pilgrims and locals alike. Until 2018, it was available only in Mecca, Medina and Jeddah, and traveling to Jeddah just to get a taste of the fried chicken was common.
+
+In pre-modern Mecca, the most common sports were impromptu wrestling and foot races.[98] Football is now the most popular sport in Mecca and the kingdom, and the city hosts some of the oldest sport clubs in Saudi Arabia such as Al Wahda FC (established in 1945). King Abdulaziz Stadium is the largest stadium in Mecca with a capacity of 38,000.[107]
+
+Mecca is very densely populated. Most long-term residents of Mecca live in the Old City, the area around the Great Mosque and many work to support pilgrims, known locally as the Hajj industry. 'Iyad Madani, the Saudi Arabian Minister for Hajj, was quoted saying, "We never stop preparing for the Hajj."[108]
+
+Year-round, pilgrims stream into the city to perform the rites of 'Umrah, and during the last weeks of eleventh Islamic month, Dhu al-Qi'dah, on average 2-4 million Muslims arrive in the city to take part in the rites known as Hajj.[109] Pilgrims are from varying ethnicities and backgrounds, mainly South and Southeast Asia, Europe and Africa. Many of these pilgrims have remained and become residents of the city. The Burmese are an older, more established community who number roughly 250,000.[110] Adding to this, the discovery of oil in the past 50 years has brought hundreds of thousands of working immigrants.
+
+Non-Muslims are not permitted to enter Mecca under Saudi law,[10] and using fraudulent documents to do so may result in arrest and prosecution.[111] The prohibition extends to Ahmadis, as they are considered non-Muslims.[112] Nevertheless, many non-Muslims and Ahmadis have visited the city as these restrictions are loosely enforced. The first such recorded example of a non-Muslim entering the city is that of Ludovico di Varthema of Bologna in 1503.[113] Guru Nanak Sahib, the founder of Sikhism, visited Mecca[114] in December 1518.[115] One of the most famous was Richard Francis Burton,[116] who traveled as a Qadiriyya Sufi from Afghanistan in 1853.
+
+Mecca Province is the only province where expatriates outnumber Saudis.[117]
+
+The first press was brought to Mecca in 1885 by Osman Nuri Pasha, an Ottoman Wāli. During the Hashemite period, it was used to print the city's official gazette, Al Qibla. The Saudi regime expanded this press into a larger operation, introducing the new Saudi official gazette of Mecca, Umm al-Qurā.[98] Mecca also has its own paper owned by the city, Al Nadwa. However, other Saudi newspapers are also provided in Mecca such as the Saudi Gazette, Al Madinah, Okaz and Al Bilad, in addition to other international newspapers.
+
+Telecommunications in the city were emphasized early under the Saudi reign. King Abdulaziz pressed them forward as he saw them as a means of convenience and better governance. While under Hussein bin Ali, there were about 20 public telephones in the entire city; in 1936, the number jumped to 450, totaling about half the telephones in the country. During that time, telephone lines were extended to Jeddah and Ta’if, but not to the capital, Riyadh. By 1985, Mecca, like other Saudi cities, possessed modern telephone, telex, radio and television communications.[98] Many television stations serving the city area include Saudi TV1, Saudi TV2, Saudi TV Sports, Al-Ekhbariya, Arab Radio and Television Network and various cable, satellite and other specialty television providers.
+
+Limited radio communication was established within the Kingdom under the Hashemites. In 1929, wireless stations were set up in various towns in the region, creating a network that would become fully functional by 1932. Soon after World War II, the existing network was greatly expanded and improved. Since then, radio communication has been used extensively in directing the pilgrimage and addressing the pilgrims. This practice started in 1950, with the initiation of broadcasts on the Day of 'Arafah (9 Dhu al-Hijjah), and increased until 1957, at which time Radio Makkah became the most powerful station in the Middle East at 50 kW. Later, power was increased 9-fold to 450 kW. Music was not immediately broadcast, but gradually folk music was introduced.[98]
+
+The only airport even close to Mecca is the Mecca East airport, which is not active. Mecca is primarily served by King Abdulaziz International Airport in Jeddah for international and regional connections and Ta'if Regional Airport for regional connections. To cater the large number of Hajj pilgrims, this airport has Hajj Terminal, specifically for use in the Hajj season, which can accommodate 47 planes simultaneously and can receive 3,800 pilgrims per hour during the Hajj season.[118]
+
+Mecca, similar to Medina, lies at the junction of two of the most important highways in Saudi Arabia, Highway 40, connecting it to the important port city of Jeddah in the west and the capital of Riyadh and the other major port city, Dammam, in the east. The other, Highway 15, connects Mecca to the other holy Islamic city of Medina approximately 400 km (250 mi) in the north and onward to Tabuk and Jordan. While in the south, it connects Mecca to Abha and Jizan.[119][120] Mecca is served by four ring roads, and these are very crowded compared to the three ring roads of Medina.
+
+The Al Masha'er Al Muqaddassah Metro is a metro line in Mecca opened on 13 November 2010.[121] The 18.1-kilometer (11.2-mile) elevated metro transports pilgrims to the holy sites of 'Arafat, Muzdalifah and Mina in the city to reduce congestion on the road and is only operational during the Hajj season.[122] It consists of nine stations, three in each of the aforementioned towns.
+
+The Mecca Metro, officially known as Mecca Mass Rail Transit, is a planned four-line metro system for the city.[123] This will be in addition to[123] the Al Masha'er Al Muqaddassah Metro which carries pilgrims.
+
+In 2018, a high speed intercity rail line, part of the Haramain High Speed Rail Project, named the Haramain high-speed railway line entered operation, connecting the holy cities cities of Mecca and Medina together via Jeddah, King Abdulaziz International Airport and King Abdullah Economic City in Rabigh.[124][125] The railway consists of 35 electric trains and is capable of transporting 60 million passengers annually. Each train can achieve speeds of up to 300 kmh (190 mph), traveling a total distance of 450 km (280 mi), reducing the travel time between the two cities to less than two hours.[126][125] It was built by a business consortium from Spain.[127]

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+
+Medicine is the science and practice of establishing the diagnosis, prognosis, treatment, and prevention of disease. Medicine encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness. Contemporary medicine applies biomedical sciences, biomedical research, genetics, and medical technology to diagnose, treat, and prevent injury and disease, typically through pharmaceuticals or surgery, but also through therapies as diverse as psychotherapy, external splints and traction, medical devices, biologics, and ionizing radiation, amongst others.[1]
+
+Medicine has been around for thousands of years, during most of which it was an art (an area of skill and knowledge) frequently having connections to the religious and philosophical beliefs of local culture. For example, a medicine man would apply herbs and say prayers for healing, or an ancient philosopher and physician would apply bloodletting according to the theories of humorism. In recent centuries, since the advent of modern science, most medicine has become a combination of art and science (both basic and applied, under the umbrella of medical science). While stitching technique for sutures is an art learned through practice, the knowledge of what happens at the cellular and molecular level in the tissues being stitched arises through science.
+
+Prescientific forms of medicine are now known as traditional medicine and folk medicine. They remain commonly used with, or instead of, scientific medicine and are thus called alternative medicine. As an example, evidence on the effectiveness of acupuncture is "variable and inconsistent" for any condition,[2] but is generally safe when done by an appropriately trained practitioner.[3] In contrast, alternative treatments outside the bounds not just of scientific medicine, but also outside the bounds of safety and efficacy are termed quackery. This can encompass an array of practices and practitioners, irrespective of whether they are prescientific (traditional medicine and folk medicine) or modern pseudo-scientific, including chiropractic which rejects modern scientific germ theory of disease (instead believing without evidence that human diseases are caused by invisible subluxation of the bones, predominantly of the spine and less so of other bones), with just over half of chiropractors also rejecting the science of immunization.
+
+Medicine (UK: /ˈmɛdsɪn/ (listen), US: /ˈmɛdɪsɪn/ (listen)) is the science and practice of the diagnosis, prognosis, treatment, and prevention of disease.[4][5] The word "medicine" is derived from Latin medicus, meaning "a physician".[6][7]
+
+Medical availability and clinical practice varies across the world due to regional differences in culture and technology. Modern scientific medicine is highly developed in the Western world, while in developing countries such as parts of Africa or Asia, the population may rely more heavily on traditional medicine with limited evidence and efficacy and no required formal training for practitioners.[8] In the developed world, evidence-based medicine is not universally used in clinical practice; for example, a 2007 survey of literature reviews found that about 49% of the interventions lacked sufficient evidence to support either benefit or harm.[9]
+
+In modern clinical practice, physicians personally assess patients in order to diagnose, prognose, treat, and prevent disease using clinical judgment. The doctor-patient relationship typically begins an interaction with an examination of the patient's medical history and medical record, followed by a medical interview[10] and a physical examination. Basic diagnostic medical devices (e.g. stethoscope, tongue depressor) are typically used. After examination for signs and interviewing for symptoms, the doctor may order medical tests (e.g. blood tests), take a biopsy, or prescribe pharmaceutical drugs or other therapies. Differential diagnosis methods help to rule out conditions based on the information provided. During the encounter, properly informing the patient of all relevant facts is an important part of the relationship and the development of trust. The medical encounter is then documented in the medical record, which is a legal document in many jurisdictions.[11] Follow-ups may be shorter but follow the same general procedure, and specialists follow a similar process. The diagnosis and treatment may take only a few minutes or a few weeks depending upon the complexity of the issue.
+
+The components of the medical interview[10] and encounter are:
+
+The physical examination is the examination of the patient for medical signs of disease, which are objective and observable, in contrast to symptoms that are volunteered by the patient and not necessarily objectively observable.[12] The healthcare provider uses sight, hearing, touch, and sometimes smell (e.g., in infection, uremia, diabetic ketoacidosis). Four actions are the basis of physical examination: inspection, palpation (feel), percussion (tap to determine resonance characteristics), and auscultation (listen), generally in that order although auscultation occurs prior to percussion and palpation for abdominal assessments.[13]
+
+The clinical examination involves the study of:
+
+It is to likely focus on areas of interest highlighted in the medical history and may not include everything listed above.
+
+The treatment plan may include ordering additional medical laboratory tests and medical imaging studies, starting therapy, referral to a specialist, or watchful observation. Follow-up may be advised. Depending upon the health insurance plan and the managed care system, various forms of "utilization review", such as prior authorization of tests, may place barriers on accessing expensive services.[14]
+
+The medical decision-making (MDM) process involves analysis and synthesis of all the above data to come up with a list of possible diagnoses (the differential diagnoses), along with an idea of what needs to be done to obtain a definitive diagnosis that would explain the patient's problem.
+
+On subsequent visits, the process may be repeated in an abbreviated manner to obtain any new history, symptoms, physical findings, and lab or imaging results or specialist consultations.
+
+Contemporary medicine is in general conducted within health care systems. Legal, credentialing and financing frameworks are established by individual governments, augmented on occasion by international organizations, such as churches. The characteristics of any given health care system have significant impact on the way medical care is provided.
+
+From ancient times, Christian emphasis on practical charity gave rise to the development of systematic nursing and hospitals and the Catholic Church today remains the largest non-government provider of medical services in the world.[15] Advanced industrial countries (with the exception of the United States)[16][17] and many developing countries provide medical services through a system of universal health care that aims to guarantee care for all through a single-payer health care system, or compulsory private or co-operative health insurance. This is intended to ensure that the entire population has access to medical care on the basis of need rather than ability to pay. Delivery may be via private medical practices or by state-owned hospitals and clinics, or by charities, most commonly by a combination of all three.
+
+Most tribal societies provide no guarantee of healthcare for the population as a whole. In such societies, healthcare is available to those that can afford to pay for it or have self-insured it (either directly or as part of an employment contract) or who may be covered by care financed by the government or tribe directly.
+
+Transparency of information is another factor defining a delivery system. Access to information on conditions, treatments, quality, and pricing greatly affects the choice by patients/consumers and, therefore, the incentives of medical professionals. While the US healthcare system has come under fire for lack of openness,[18] new legislation may encourage greater openness. There is a perceived tension between the need for transparency on the one hand and such issues as patient confidentiality and the possible exploitation of information for commercial gain on the other.
+
+Provision of medical care is classified into primary, secondary, and tertiary care categories.
+
+Primary care medical services are provided by physicians, physician assistants, nurse practitioners, or other health professionals who have first contact with a patient seeking medical treatment or care. These occur in physician offices, clinics, nursing homes, schools, home visits, and other places close to patients. About 90% of medical visits can be treated by the primary care provider. These include treatment of acute and chronic illnesses, preventive care and health education for all ages and both sexes.
+
+Secondary care medical services are provided by medical specialists in their offices or clinics or at local community hospitals for a patient referred by a primary care provider who first diagnosed or treated the patient. Referrals are made for those patients who required the expertise or procedures performed by specialists. These include both ambulatory care and inpatient services, Emergency departments, intensive care medicine, surgery services, physical therapy, labor and delivery, endoscopy units, diagnostic laboratory and medical imaging services, hospice centers, etc. Some primary care providers may also take care of hospitalized patients and deliver babies in a secondary care setting.
+
+Tertiary care medical services are provided by specialist hospitals or regional centers equipped with diagnostic and treatment facilities not generally available at local hospitals. These include trauma centers, burn treatment centers, advanced neonatology unit services, organ transplants, high-risk pregnancy, radiation oncology, etc.
+
+Modern medical care also depends on information – still delivered in many health care settings on paper records, but increasingly nowadays by electronic means.
+
+In low-income countries, modern healthcare is often too expensive for the average person. International healthcare policy researchers have advocated that "user fees" be removed in these areas to ensure access, although even after removal, significant costs and barriers remain.[19]
+
+Separation of prescribing and dispensing is a practice in medicine and pharmacy in which the physician who provides a medical prescription is independent from the  pharmacist who provides the prescription drug. In the Western world there are centuries of tradition for separating pharmacists from physicians. In Asian countries, it is traditional for physicians to also provide drugs.[20]
+
+Working together as an interdisciplinary team, many highly trained health professionals besides medical practitioners are involved in the delivery of modern health care. Examples include: nurses, emergency medical technicians and paramedics, laboratory scientists, pharmacists, podiatrists, physiotherapists, respiratory therapists, speech therapists, occupational therapists, radiographers, dietitians, and bioengineers, medical physics, surgeons, surgeon's assistant, surgical technologist.
+
+The scope and sciences underpinning human medicine overlap many other fields. Dentistry, while considered by some a separate discipline from medicine, is a medical field.
+
+A patient admitted to the hospital is usually under the care of a specific team based on their main presenting problem, e.g., the cardiology team, who then may interact with other specialties, e.g., surgical, radiology, to help diagnose or treat the main problem or any subsequent complications/developments.
+
+Physicians have many specializations and subspecializations into certain branches of medicine, which are listed below. There are variations from country to country regarding which specialties certain subspecialties are in.
+
+The main branches of medicine are:
+
+In the broadest meaning of "medicine", there are many different specialties. In the UK, most specialities have their own body or college, which has its own entrance examination. These are collectively known as the Royal Colleges, although not all currently use the term "Royal". The development of a speciality is often driven by new technology (such as the development of effective anaesthetics) or ways of working (such as emergency departments); the new specialty leads to the formation of a unifying body of doctors and the prestige of administering their own examination.
+
+Within medical circles, specialities usually fit into one of two broad categories: "Medicine" and "Surgery." "Medicine" refers to the practice of non-operative medicine, and most of its subspecialties require preliminary training in Internal Medicine. In the UK, this was traditionally evidenced by passing the examination for the Membership of the Royal College of Physicians (MRCP) or the equivalent college in Scotland or Ireland. "Surgery" refers to the practice of operative medicine, and most subspecialties in this area require preliminary training in General Surgery, which in the UK leads to membership of the Royal College of Surgeons of England (MRCS). At present, some specialties of medicine do not fit easily into either of these categories, such as radiology, pathology, or anesthesia. Most of these have branched from one or other of the two camps above; for example anaesthesia developed first as a faculty of the Royal College of Surgeons (for which MRCS/FRCS would have been required) before becoming the Royal College of Anaesthetists and membership of the college is attained by sitting for the examination of the Fellowship of the Royal College of Anesthetists (FRCA).
+
+Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate or treat a pathological condition such as disease or injury, to help improve bodily function or appearance or to repair unwanted ruptured areas (for example, a perforated ear drum). Surgeons must also manage pre-operative, post-operative, and potential surgical candidates on the hospital wards. Surgery has many sub-specialties, including general surgery, ophthalmic surgery, cardiovascular surgery, colorectal surgery, neurosurgery, oral and maxillofacial surgery, oncologic surgery, orthopedic surgery, otolaryngology, plastic surgery, podiatric surgery, transplant surgery, trauma surgery, urology, vascular surgery, and pediatric surgery. In some centers, anesthesiology is part of the division of surgery (for historical and logistical reasons), although it is not a surgical discipline. Other medical specialties may employ surgical procedures, such as ophthalmology and dermatology, but are not considered surgical sub-specialties per se.
+
+Surgical training in the U.S. requires a minimum of five years of residency after medical school. Sub-specialties of surgery often require seven or more years. In addition, fellowships can last an additional one to three years. Because post-residency fellowships can be competitive, many trainees devote two additional years to research. Thus in some cases surgical training will not finish until more than a decade after medical school. Furthermore, surgical training can be very difficult and time-consuming.
+
+Internal medicine is the medical specialty dealing with the prevention, diagnosis, and treatment of adult diseases. According to some sources, an emphasis on internal structures is implied.[21] In North America, specialists in internal medicine are commonly called "internists." Elsewhere, especially in Commonwealth nations, such specialists are often called physicians.[22] These terms, internist or physician (in the narrow sense, common outside North America), generally exclude practitioners of gynecology and obstetrics, pathology, psychiatry, and especially surgery and its subspecialities.
+
+Because their patients are often seriously ill or require complex investigations, internists do much of their work in hospitals. Formerly, many internists were not subspecialized; such general physicians would see any complex nonsurgical problem; this style of practice has become much less common. In modern urban practice, most internists are subspecialists: that is, they generally limit their medical practice to problems of one organ system or to one particular area of medical knowledge. For example, gastroenterologists and nephrologists specialize respectively in diseases of the gut and the kidneys.[23]
+
+In the Commonwealth of Nations and some other countries, specialist pediatricians and geriatricians are also described as specialist physicians (or internists) who have subspecialized by age of patient rather than by organ system. Elsewhere, especially in North America, general pediatrics is often a form of primary care.
+
+There are many subspecialities (or subdisciplines) of internal medicine:
+
+Training in internal medicine (as opposed to surgical training), varies considerably across the world: see the articles on medical education and physician for more details. In North America, it requires at least three years of residency training after medical school, which can then be followed by a one- to three-year fellowship in the subspecialties listed above. In general, resident work hours in medicine are less than those in surgery, averaging about 60 hours per week in the US. This difference does not apply in the UK where all doctors are now required by law to work less than 48 hours per week on average.
+
+The following are some major medical specialties that do not directly fit into any of the above-mentioned groups:
+
+Some interdisciplinary sub-specialties of medicine include:
+
+Medical education and training varies around the world. It typically involves entry level education at a university medical school, followed by a period of supervised practice or internship, or residency. This can be followed by postgraduate vocational training. A variety of teaching methods have been employed in medical education, still itself a focus of active research. In Canada and the United States of America, a Doctor of Medicine degree, often abbreviated M.D., or a Doctor of Osteopathic Medicine degree, often abbreviated as D.O. and unique to the United States, must be completed in and delivered from a recognized university.
+
+Since knowledge, techniques, and medical technology continue to evolve at a rapid rate, many regulatory authorities require continuing medical education. Medical practitioners upgrade their knowledge in various ways, including medical journals, seminars, conferences, and online programs.  A database of objectives covering medical knowledge, as suggested by national societies across the United States, can be searched at http://data.medobjectives.marian.edu/.[25]
+
+In most countries, it is a legal requirement for a medical doctor to be licensed or registered. In general, this entails a medical degree from a university and accreditation by a medical board or an equivalent national organization, which may ask the applicant to pass exams. This restricts the considerable legal authority of the medical profession to physicians that are trained and qualified by national standards. It is also intended as an assurance to patients and as a safeguard against charlatans that practice inadequate medicine for personal gain. While the laws generally require medical doctors to be trained in "evidence based", Western, or Hippocratic Medicine, they are not intended to discourage different paradigms of health.
+
+In the European Union, the profession of doctor of medicine is regulated. A profession is said to be regulated when access and exercise is subject to the possession of a specific professional qualification.
+The regulated professions database contains a list of regulated professions for doctor of medicine in the EU member states, EEA countries and Switzerland. This list is covered by the Directive 2005/36/EC.
+
+Doctors who are negligent or intentionally harmful in their care of patients can face charges of medical malpractice and be subject to civil, criminal, or professional sanctions.
+
+Medical ethics is a system of moral principles that apply values and judgments to the practice of medicine. As a scholarly discipline, medical ethics encompasses its practical application in clinical settings as well as work on its history, philosophy, theology, and sociology. Six of the values that commonly apply to medical ethics discussions are:
+
+Values such as these do not give answers as to how to handle a particular situation, but provide a useful framework for understanding conflicts. When moral values are in conflict, the result may be an ethical dilemma or crisis. Sometimes, no good solution to a dilemma in medical ethics exists, and occasionally, the values of the medical community (i.e., the hospital and its staff) conflict with the values of the individual patient, family, or larger non-medical community. Conflicts can also arise between health care providers, or among family members. For example, some argue that the principles of autonomy and beneficence clash when patients refuse blood transfusions, considering them life-saving; and truth-telling was not emphasized to a large extent before the HIV era.
+
+Prehistoric medicine incorporated plants (herbalism), animal parts, and minerals. In many cases these materials were used ritually as magical substances by priests, shamans, or medicine men. Well-known spiritual systems include animism (the notion of inanimate objects having spirits), spiritualism (an appeal to gods or communion with ancestor spirits); shamanism (the vesting of an individual with mystic powers); and divination (magically obtaining the truth). The field of medical anthropology examines the ways in which culture and society are organized around or impacted by issues of health, health care and related issues.
+
+Early records on medicine have been discovered from ancient Egyptian medicine, Babylonian Medicine, Ayurvedic medicine (in the Indian subcontinent), classical Chinese medicine (predecessor to the modern traditional Chinese medicine), and ancient Greek medicine and Roman medicine.
+
+In Egypt, Imhotep (3rd millennium BCE) is the first physician in history known by name. The oldest Egyptian medical text is the Kahun Gynaecological Papyrus from around 2000 BCE, which describes gynaecological diseases. The Edwin Smith Papyrus dating back to 1600 BCE is an early work on surgery, while the Ebers Papyrus dating back to 1500 BCE is akin to a textbook on medicine.[26]
+
+In China, archaeological evidence of medicine in Chinese dates back to the Bronze Age Shang Dynasty, based on seeds for herbalism and tools presumed to have been used for surgery.[27] The Huangdi Neijing, the progenitor of Chinese medicine, is a medical text written beginning in the 2nd century BCE and compiled in the 3rd century.[28]
+
+In India, the surgeon Sushruta described numerous surgical operations, including the earliest forms of plastic surgery.[29][dubious  – discuss][30] Earliest records of dedicated hospitals come from Mihintale in Sri Lanka where evidence of dedicated medicinal treatment facilities for patients are found.[31][32]
+
+In Greece, the Greek physician Hippocrates, the "father of modern medicine",[33][34] laid the foundation for a rational approach to medicine. Hippocrates introduced the Hippocratic Oath for physicians, which is still relevant and in use today, and was the first to categorize illnesses as acute, chronic, endemic and epidemic, and use terms such as, "exacerbation, relapse, resolution, crisis, paroxysm, peak, and convalescence".[35][36] The Greek physician Galen was also one of the greatest surgeons of the ancient world and performed many audacious operations, including brain and eye surgeries. After the fall of the Western Roman Empire and the onset of the Early Middle Ages, the Greek tradition of medicine went into decline in Western Europe, although it continued uninterrupted in the Eastern Roman (Byzantine) Empire.
+
+Most of our knowledge of ancient Hebrew medicine during the 1st millennium BC comes from the Torah, i.e. the Five Books of Moses, which contain various health related laws and rituals. The Hebrew contribution to the development of modern medicine started in the Byzantine Era, with the physician Asaph the Jew.[37]
+
+The concept of hospital as institution to offer medical care and possibility of a cure for the patients due to the ideals of Christian charity, rather than just merely a place to die, appeared in the Byzantine Empire.[38]
+
+Although the concept of uroscopy was known to Galen, he did not see the importance of using it to localize the disease. It was under the Byzantines with physicians such of Theophilus Protospatharius that they realized the potential in uroscopy to determine disease in a time when no microscope or stethoscope existed. That practice eventually spread to the rest of Europe.[39]
+
+After 750 CE, the Muslim world had the works of Hippocrates, Galen and Sushruta translated into Arabic, and Islamic physicians engaged in some significant medical research. Notable Islamic medical pioneers include the Persian polymath, Avicenna, who, along with Imhotep and Hippocrates, has also been called the "father of medicine".[40] He wrote The Canon of Medicine which became a standard medical text at many medieval European universities,[41] considered one of the most famous books in the history of medicine.[42] Others include Abulcasis,[43] Avenzoar,[44] Ibn al-Nafis,[45] and Averroes.[46] Persian  physician Rhazes[47] was one of the first to question the Greek theory of humorism, which nevertheless remained influential in both medieval Western and medieval Islamic medicine.[48] Some volumes of Rhazes's work Al-Mansuri, namely "On Surgery" and "A General Book on Therapy", became part of the medical curriculum in European universities.[49] Additionally, he has been described as a doctor's doctor,[50] the father of pediatrics,[51][52] and a pioneer of ophthalmology. For example, he was the first to recognize the reaction of the eye's pupil to light.[52] The Persian Bimaristan hospitals were an early example of public hospitals.[53][54]
+
+In Europe, Charlemagne decreed that a hospital should be attached to each cathedral and monastery and the historian Geoffrey Blainey likened the activities of the Catholic Church in health care during the Middle Ages to an early version of a welfare state: "It conducted hospitals for the old and orphanages for the young; hospices for the sick of all ages; places for the lepers; and hostels or inns where pilgrims could buy a cheap bed and meal". It supplied food to the population during famine and distributed food to the poor. This welfare system the church funded through collecting taxes on a large scale and possessing large farmlands and estates. The Benedictine order was noted for setting up hospitals and infirmaries in their monasteries, growing medical herbs and becoming the chief medical care givers of their districts, as at the great Abbey of Cluny. The Church also established a network of cathedral schools and universities where medicine was studied. The Schola Medica Salernitana in Salerno, looking to the learning of Greek and Arab physicians, grew to be the finest medical school in Medieval Europe.[55]
+
+However, the fourteenth and fifteenth century Black Death devastated both the Middle East and Europe, and it has even been argued that Western Europe was generally more effective in recovering from the pandemic than the Middle East.[56] In the early modern period, important early figures in medicine and anatomy emerged in Europe, including Gabriele Falloppio and William Harvey.
+
+The major shift in medical thinking was the gradual rejection, especially during the Black Death in the 14th and 15th centuries, of what may be called the 'traditional authority' approach to science and medicine. This was the notion that because some prominent person in the past said something must be so, then that was the way it was, and anything one observed to the contrary was an anomaly (which was paralleled by a similar shift in European society in general – see Copernicus's rejection of Ptolemy's theories on astronomy). Physicians like Vesalius improved upon or disproved some of the theories from the past. The main tomes used both by medicine students and expert physicians were Materia Medica and Pharmacopoeia.
+
+Andreas Vesalius was the author of De humani corporis fabrica, an important book on human anatomy.[57] Bacteria and microorganisms were first observed with a microscope by Antonie van Leeuwenhoek in 1676, initiating the scientific field microbiology.[58] Independently from Ibn al-Nafis, Michael Servetus rediscovered the pulmonary circulation, but this discovery did not reach the public because it was written down for the first time in the "Manuscript of Paris"[59] in 1546, and later published in the theological work for which he paid with his life in 1553. Later this was described by Renaldus Columbus and Andrea Cesalpino. Herman Boerhaave is sometimes referred to as a "father of physiology" due to his exemplary teaching in Leiden and textbook 'Institutiones medicae' (1708). Pierre Fauchard has been called "the father of modern dentistry".[60]
+
+Veterinary medicine was, for the first time, truly separated from human medicine in 1761, when the French veterinarian Claude Bourgelat founded the world's first veterinary school in Lyon, France. Before this, medical doctors treated both humans and other animals.
+
+Modern scientific biomedical research (where results are testable and reproducible) began to replace early Western traditions based on herbalism, the Greek "four humours" and other such pre-modern notions. The modern era really began with Edward Jenner's discovery of the smallpox vaccine at the end of the 18th century (inspired by the method of inoculation earlier practiced in Asia), Robert Koch's discoveries around 1880 of the transmission of disease by bacteria, and then the discovery of antibiotics around 1900.
+
+The post-18th century modernity period brought more groundbreaking researchers from Europe. From Germany and Austria, doctors Rudolf Virchow, Wilhelm Conrad Röntgen, Karl Landsteiner and Otto Loewi made notable contributions. In the United Kingdom, Alexander Fleming, Joseph Lister, Francis Crick and Florence Nightingale are considered important. Spanish doctor Santiago Ramón y Cajal is considered the father of modern neuroscience.
+
+From New Zealand and Australia came Maurice Wilkins, Howard Florey, and Frank Macfarlane Burnet.
+
+Others that did significant work include William Williams Keen, William Coley, James D. Watson (United States); Salvador Luria (Italy); Alexandre Yersin (Switzerland); Kitasato Shibasaburō (Japan); Jean-Martin Charcot, Claude Bernard, Paul Broca (France); Adolfo Lutz (Brazil); Nikolai Korotkov (Russia); Sir William Osler (Canada); and Harvey Cushing (United States).
+
+As science and technology developed, medicine became more reliant upon medications. Throughout history and in Europe right until the late 18th century, not only animal and plant products were used as medicine, but also human body parts and fluids.[61] Pharmacology developed in part from herbalism and some drugs are still derived from plants (atropine, ephedrine, warfarin, aspirin, digoxin, vinca alkaloids,[62] taxol, hyoscine, etc.).[63] Vaccines were discovered by Edward Jenner and Louis Pasteur.
+
+The first antibiotic was arsphenamine (Salvarsan) discovered by Paul Ehrlich in 1908 after he observed that bacteria took up toxic dyes that human cells did not. The first major class of antibiotics was the sulfa drugs, derived by German chemists originally from azo dyes.
+
+Pharmacology has become increasingly sophisticated; modern biotechnology allows drugs targeted towards specific physiological processes to be developed, sometimes designed for compatibility with the body to reduce side-effects. Genomics and knowledge of human genetics and human evolution is having increasingly significant influence on medicine, as the causative genes of most monogenic genetic disorders have now been identified, and the development of techniques in molecular biology, evolution, and genetics are influencing medical technology, practice and decision-making.
+
+Evidence-based medicine is a contemporary movement to establish the most effective algorithms of practice (ways of doing things) through the use of systematic reviews and meta-analysis. The movement is facilitated by modern global information science, which allows as much of the available evidence as possible to be collected and analyzed according to standard protocols that are then disseminated to healthcare providers. The Cochrane Collaboration leads this movement. A 2001 review of 160 Cochrane systematic reviews revealed that, according to two readers, 21.3% of the reviews concluded insufficient evidence, 20% concluded evidence of no effect, and 22.5% concluded positive effect.[64]
+
+Evidence-based medicine, prevention of medical error (and other "iatrogenesis"), and avoidance of unnecessary health care are a priority in modern medical systems. These topics generate significant political and public policy attention, particularly in the United States where healthcare is regarded as excessively costly but population health metrics lag similar nations.[65]
+
+Globally, many developing countries lack access to care and access to medicines.[66] As of 2015, most wealthy developed countries provide health care to all citizens, with a few exceptions such as the United States where lack of health insurance coverage may limit access.[67]
+
+The World Health Organization (WHO) defines traditional medicine as "the sum total of the knowledge, skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures, whether explicable or not, used in the maintenance of health as well as in the prevention, diagnosis, improvement or treatment of physical and mental illness."[68] Practices known as traditional medicines include Ayurveda, Siddha medicine, Unani, ancient Iranian medicine, Irani, Islamic medicine, traditional Chinese medicine, traditional Korean medicine, acupuncture, Muti, Ifá, and traditional African medicine.
+
+The WHO stated that "inappropriate use of traditional medicines or practices can have negative or dangerous effects" and that "further research is needed to ascertain the efficacy and safety" of several of the practices and medicinal plants used by traditional medicine systems.[68] As example, Indian Medical Association regard traditional medicine practices, such as Ayurveda and Siddha medicine, as quackery.[69][70][71] Practitioners of traditional medicine are not authorized to practice medicine in India unless trained at a qualified medical institution, registered with the government, and listed as registered physicians annually in The Gazette of India.[69][70] Identifying practitioners of traditional medicine, the Supreme Court of India stated in 2018 that "unqualified, untrained quacks are posing a great risk to the entire society and playing with the lives of people without having the requisite training and education in the science from approved institutions".[69]
+

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+
+
+Medicine is the science and practice of establishing the diagnosis, prognosis, treatment, and prevention of disease. Medicine encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness. Contemporary medicine applies biomedical sciences, biomedical research, genetics, and medical technology to diagnose, treat, and prevent injury and disease, typically through pharmaceuticals or surgery, but also through therapies as diverse as psychotherapy, external splints and traction, medical devices, biologics, and ionizing radiation, amongst others.[1]
+
+Medicine has been around for thousands of years, during most of which it was an art (an area of skill and knowledge) frequently having connections to the religious and philosophical beliefs of local culture. For example, a medicine man would apply herbs and say prayers for healing, or an ancient philosopher and physician would apply bloodletting according to the theories of humorism. In recent centuries, since the advent of modern science, most medicine has become a combination of art and science (both basic and applied, under the umbrella of medical science). While stitching technique for sutures is an art learned through practice, the knowledge of what happens at the cellular and molecular level in the tissues being stitched arises through science.
+
+Prescientific forms of medicine are now known as traditional medicine and folk medicine. They remain commonly used with, or instead of, scientific medicine and are thus called alternative medicine. As an example, evidence on the effectiveness of acupuncture is "variable and inconsistent" for any condition,[2] but is generally safe when done by an appropriately trained practitioner.[3] In contrast, alternative treatments outside the bounds not just of scientific medicine, but also outside the bounds of safety and efficacy are termed quackery. This can encompass an array of practices and practitioners, irrespective of whether they are prescientific (traditional medicine and folk medicine) or modern pseudo-scientific, including chiropractic which rejects modern scientific germ theory of disease (instead believing without evidence that human diseases are caused by invisible subluxation of the bones, predominantly of the spine and less so of other bones), with just over half of chiropractors also rejecting the science of immunization.
+
+Medicine (UK: /ˈmɛdsɪn/ (listen), US: /ˈmɛdɪsɪn/ (listen)) is the science and practice of the diagnosis, prognosis, treatment, and prevention of disease.[4][5] The word "medicine" is derived from Latin medicus, meaning "a physician".[6][7]
+
+Medical availability and clinical practice varies across the world due to regional differences in culture and technology. Modern scientific medicine is highly developed in the Western world, while in developing countries such as parts of Africa or Asia, the population may rely more heavily on traditional medicine with limited evidence and efficacy and no required formal training for practitioners.[8] In the developed world, evidence-based medicine is not universally used in clinical practice; for example, a 2007 survey of literature reviews found that about 49% of the interventions lacked sufficient evidence to support either benefit or harm.[9]
+
+In modern clinical practice, physicians personally assess patients in order to diagnose, prognose, treat, and prevent disease using clinical judgment. The doctor-patient relationship typically begins an interaction with an examination of the patient's medical history and medical record, followed by a medical interview[10] and a physical examination. Basic diagnostic medical devices (e.g. stethoscope, tongue depressor) are typically used. After examination for signs and interviewing for symptoms, the doctor may order medical tests (e.g. blood tests), take a biopsy, or prescribe pharmaceutical drugs or other therapies. Differential diagnosis methods help to rule out conditions based on the information provided. During the encounter, properly informing the patient of all relevant facts is an important part of the relationship and the development of trust. The medical encounter is then documented in the medical record, which is a legal document in many jurisdictions.[11] Follow-ups may be shorter but follow the same general procedure, and specialists follow a similar process. The diagnosis and treatment may take only a few minutes or a few weeks depending upon the complexity of the issue.
+
+The components of the medical interview[10] and encounter are:
+
+The physical examination is the examination of the patient for medical signs of disease, which are objective and observable, in contrast to symptoms that are volunteered by the patient and not necessarily objectively observable.[12] The healthcare provider uses sight, hearing, touch, and sometimes smell (e.g., in infection, uremia, diabetic ketoacidosis). Four actions are the basis of physical examination: inspection, palpation (feel), percussion (tap to determine resonance characteristics), and auscultation (listen), generally in that order although auscultation occurs prior to percussion and palpation for abdominal assessments.[13]
+
+The clinical examination involves the study of:
+
+It is to likely focus on areas of interest highlighted in the medical history and may not include everything listed above.
+
+The treatment plan may include ordering additional medical laboratory tests and medical imaging studies, starting therapy, referral to a specialist, or watchful observation. Follow-up may be advised. Depending upon the health insurance plan and the managed care system, various forms of "utilization review", such as prior authorization of tests, may place barriers on accessing expensive services.[14]
+
+The medical decision-making (MDM) process involves analysis and synthesis of all the above data to come up with a list of possible diagnoses (the differential diagnoses), along with an idea of what needs to be done to obtain a definitive diagnosis that would explain the patient's problem.
+
+On subsequent visits, the process may be repeated in an abbreviated manner to obtain any new history, symptoms, physical findings, and lab or imaging results or specialist consultations.
+
+Contemporary medicine is in general conducted within health care systems. Legal, credentialing and financing frameworks are established by individual governments, augmented on occasion by international organizations, such as churches. The characteristics of any given health care system have significant impact on the way medical care is provided.
+
+From ancient times, Christian emphasis on practical charity gave rise to the development of systematic nursing and hospitals and the Catholic Church today remains the largest non-government provider of medical services in the world.[15] Advanced industrial countries (with the exception of the United States)[16][17] and many developing countries provide medical services through a system of universal health care that aims to guarantee care for all through a single-payer health care system, or compulsory private or co-operative health insurance. This is intended to ensure that the entire population has access to medical care on the basis of need rather than ability to pay. Delivery may be via private medical practices or by state-owned hospitals and clinics, or by charities, most commonly by a combination of all three.
+
+Most tribal societies provide no guarantee of healthcare for the population as a whole. In such societies, healthcare is available to those that can afford to pay for it or have self-insured it (either directly or as part of an employment contract) or who may be covered by care financed by the government or tribe directly.
+
+Transparency of information is another factor defining a delivery system. Access to information on conditions, treatments, quality, and pricing greatly affects the choice by patients/consumers and, therefore, the incentives of medical professionals. While the US healthcare system has come under fire for lack of openness,[18] new legislation may encourage greater openness. There is a perceived tension between the need for transparency on the one hand and such issues as patient confidentiality and the possible exploitation of information for commercial gain on the other.
+
+Provision of medical care is classified into primary, secondary, and tertiary care categories.
+
+Primary care medical services are provided by physicians, physician assistants, nurse practitioners, or other health professionals who have first contact with a patient seeking medical treatment or care. These occur in physician offices, clinics, nursing homes, schools, home visits, and other places close to patients. About 90% of medical visits can be treated by the primary care provider. These include treatment of acute and chronic illnesses, preventive care and health education for all ages and both sexes.
+
+Secondary care medical services are provided by medical specialists in their offices or clinics or at local community hospitals for a patient referred by a primary care provider who first diagnosed or treated the patient. Referrals are made for those patients who required the expertise or procedures performed by specialists. These include both ambulatory care and inpatient services, Emergency departments, intensive care medicine, surgery services, physical therapy, labor and delivery, endoscopy units, diagnostic laboratory and medical imaging services, hospice centers, etc. Some primary care providers may also take care of hospitalized patients and deliver babies in a secondary care setting.
+
+Tertiary care medical services are provided by specialist hospitals or regional centers equipped with diagnostic and treatment facilities not generally available at local hospitals. These include trauma centers, burn treatment centers, advanced neonatology unit services, organ transplants, high-risk pregnancy, radiation oncology, etc.
+
+Modern medical care also depends on information – still delivered in many health care settings on paper records, but increasingly nowadays by electronic means.
+
+In low-income countries, modern healthcare is often too expensive for the average person. International healthcare policy researchers have advocated that "user fees" be removed in these areas to ensure access, although even after removal, significant costs and barriers remain.[19]
+
+Separation of prescribing and dispensing is a practice in medicine and pharmacy in which the physician who provides a medical prescription is independent from the  pharmacist who provides the prescription drug. In the Western world there are centuries of tradition for separating pharmacists from physicians. In Asian countries, it is traditional for physicians to also provide drugs.[20]
+
+Working together as an interdisciplinary team, many highly trained health professionals besides medical practitioners are involved in the delivery of modern health care. Examples include: nurses, emergency medical technicians and paramedics, laboratory scientists, pharmacists, podiatrists, physiotherapists, respiratory therapists, speech therapists, occupational therapists, radiographers, dietitians, and bioengineers, medical physics, surgeons, surgeon's assistant, surgical technologist.
+
+The scope and sciences underpinning human medicine overlap many other fields. Dentistry, while considered by some a separate discipline from medicine, is a medical field.
+
+A patient admitted to the hospital is usually under the care of a specific team based on their main presenting problem, e.g., the cardiology team, who then may interact with other specialties, e.g., surgical, radiology, to help diagnose or treat the main problem or any subsequent complications/developments.
+
+Physicians have many specializations and subspecializations into certain branches of medicine, which are listed below. There are variations from country to country regarding which specialties certain subspecialties are in.
+
+The main branches of medicine are:
+
+In the broadest meaning of "medicine", there are many different specialties. In the UK, most specialities have their own body or college, which has its own entrance examination. These are collectively known as the Royal Colleges, although not all currently use the term "Royal". The development of a speciality is often driven by new technology (such as the development of effective anaesthetics) or ways of working (such as emergency departments); the new specialty leads to the formation of a unifying body of doctors and the prestige of administering their own examination.
+
+Within medical circles, specialities usually fit into one of two broad categories: "Medicine" and "Surgery." "Medicine" refers to the practice of non-operative medicine, and most of its subspecialties require preliminary training in Internal Medicine. In the UK, this was traditionally evidenced by passing the examination for the Membership of the Royal College of Physicians (MRCP) or the equivalent college in Scotland or Ireland. "Surgery" refers to the practice of operative medicine, and most subspecialties in this area require preliminary training in General Surgery, which in the UK leads to membership of the Royal College of Surgeons of England (MRCS). At present, some specialties of medicine do not fit easily into either of these categories, such as radiology, pathology, or anesthesia. Most of these have branched from one or other of the two camps above; for example anaesthesia developed first as a faculty of the Royal College of Surgeons (for which MRCS/FRCS would have been required) before becoming the Royal College of Anaesthetists and membership of the college is attained by sitting for the examination of the Fellowship of the Royal College of Anesthetists (FRCA).
+
+Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate or treat a pathological condition such as disease or injury, to help improve bodily function or appearance or to repair unwanted ruptured areas (for example, a perforated ear drum). Surgeons must also manage pre-operative, post-operative, and potential surgical candidates on the hospital wards. Surgery has many sub-specialties, including general surgery, ophthalmic surgery, cardiovascular surgery, colorectal surgery, neurosurgery, oral and maxillofacial surgery, oncologic surgery, orthopedic surgery, otolaryngology, plastic surgery, podiatric surgery, transplant surgery, trauma surgery, urology, vascular surgery, and pediatric surgery. In some centers, anesthesiology is part of the division of surgery (for historical and logistical reasons), although it is not a surgical discipline. Other medical specialties may employ surgical procedures, such as ophthalmology and dermatology, but are not considered surgical sub-specialties per se.
+
+Surgical training in the U.S. requires a minimum of five years of residency after medical school. Sub-specialties of surgery often require seven or more years. In addition, fellowships can last an additional one to three years. Because post-residency fellowships can be competitive, many trainees devote two additional years to research. Thus in some cases surgical training will not finish until more than a decade after medical school. Furthermore, surgical training can be very difficult and time-consuming.
+
+Internal medicine is the medical specialty dealing with the prevention, diagnosis, and treatment of adult diseases. According to some sources, an emphasis on internal structures is implied.[21] In North America, specialists in internal medicine are commonly called "internists." Elsewhere, especially in Commonwealth nations, such specialists are often called physicians.[22] These terms, internist or physician (in the narrow sense, common outside North America), generally exclude practitioners of gynecology and obstetrics, pathology, psychiatry, and especially surgery and its subspecialities.
+
+Because their patients are often seriously ill or require complex investigations, internists do much of their work in hospitals. Formerly, many internists were not subspecialized; such general physicians would see any complex nonsurgical problem; this style of practice has become much less common. In modern urban practice, most internists are subspecialists: that is, they generally limit their medical practice to problems of one organ system or to one particular area of medical knowledge. For example, gastroenterologists and nephrologists specialize respectively in diseases of the gut and the kidneys.[23]
+
+In the Commonwealth of Nations and some other countries, specialist pediatricians and geriatricians are also described as specialist physicians (or internists) who have subspecialized by age of patient rather than by organ system. Elsewhere, especially in North America, general pediatrics is often a form of primary care.
+
+There are many subspecialities (or subdisciplines) of internal medicine:
+
+Training in internal medicine (as opposed to surgical training), varies considerably across the world: see the articles on medical education and physician for more details. In North America, it requires at least three years of residency training after medical school, which can then be followed by a one- to three-year fellowship in the subspecialties listed above. In general, resident work hours in medicine are less than those in surgery, averaging about 60 hours per week in the US. This difference does not apply in the UK where all doctors are now required by law to work less than 48 hours per week on average.
+
+The following are some major medical specialties that do not directly fit into any of the above-mentioned groups:
+
+Some interdisciplinary sub-specialties of medicine include:
+
+Medical education and training varies around the world. It typically involves entry level education at a university medical school, followed by a period of supervised practice or internship, or residency. This can be followed by postgraduate vocational training. A variety of teaching methods have been employed in medical education, still itself a focus of active research. In Canada and the United States of America, a Doctor of Medicine degree, often abbreviated M.D., or a Doctor of Osteopathic Medicine degree, often abbreviated as D.O. and unique to the United States, must be completed in and delivered from a recognized university.
+
+Since knowledge, techniques, and medical technology continue to evolve at a rapid rate, many regulatory authorities require continuing medical education. Medical practitioners upgrade their knowledge in various ways, including medical journals, seminars, conferences, and online programs.  A database of objectives covering medical knowledge, as suggested by national societies across the United States, can be searched at http://data.medobjectives.marian.edu/.[25]
+
+In most countries, it is a legal requirement for a medical doctor to be licensed or registered. In general, this entails a medical degree from a university and accreditation by a medical board or an equivalent national organization, which may ask the applicant to pass exams. This restricts the considerable legal authority of the medical profession to physicians that are trained and qualified by national standards. It is also intended as an assurance to patients and as a safeguard against charlatans that practice inadequate medicine for personal gain. While the laws generally require medical doctors to be trained in "evidence based", Western, or Hippocratic Medicine, they are not intended to discourage different paradigms of health.
+
+In the European Union, the profession of doctor of medicine is regulated. A profession is said to be regulated when access and exercise is subject to the possession of a specific professional qualification.
+The regulated professions database contains a list of regulated professions for doctor of medicine in the EU member states, EEA countries and Switzerland. This list is covered by the Directive 2005/36/EC.
+
+Doctors who are negligent or intentionally harmful in their care of patients can face charges of medical malpractice and be subject to civil, criminal, or professional sanctions.
+
+Medical ethics is a system of moral principles that apply values and judgments to the practice of medicine. As a scholarly discipline, medical ethics encompasses its practical application in clinical settings as well as work on its history, philosophy, theology, and sociology. Six of the values that commonly apply to medical ethics discussions are:
+
+Values such as these do not give answers as to how to handle a particular situation, but provide a useful framework for understanding conflicts. When moral values are in conflict, the result may be an ethical dilemma or crisis. Sometimes, no good solution to a dilemma in medical ethics exists, and occasionally, the values of the medical community (i.e., the hospital and its staff) conflict with the values of the individual patient, family, or larger non-medical community. Conflicts can also arise between health care providers, or among family members. For example, some argue that the principles of autonomy and beneficence clash when patients refuse blood transfusions, considering them life-saving; and truth-telling was not emphasized to a large extent before the HIV era.
+
+Prehistoric medicine incorporated plants (herbalism), animal parts, and minerals. In many cases these materials were used ritually as magical substances by priests, shamans, or medicine men. Well-known spiritual systems include animism (the notion of inanimate objects having spirits), spiritualism (an appeal to gods or communion with ancestor spirits); shamanism (the vesting of an individual with mystic powers); and divination (magically obtaining the truth). The field of medical anthropology examines the ways in which culture and society are organized around or impacted by issues of health, health care and related issues.
+
+Early records on medicine have been discovered from ancient Egyptian medicine, Babylonian Medicine, Ayurvedic medicine (in the Indian subcontinent), classical Chinese medicine (predecessor to the modern traditional Chinese medicine), and ancient Greek medicine and Roman medicine.
+
+In Egypt, Imhotep (3rd millennium BCE) is the first physician in history known by name. The oldest Egyptian medical text is the Kahun Gynaecological Papyrus from around 2000 BCE, which describes gynaecological diseases. The Edwin Smith Papyrus dating back to 1600 BCE is an early work on surgery, while the Ebers Papyrus dating back to 1500 BCE is akin to a textbook on medicine.[26]
+
+In China, archaeological evidence of medicine in Chinese dates back to the Bronze Age Shang Dynasty, based on seeds for herbalism and tools presumed to have been used for surgery.[27] The Huangdi Neijing, the progenitor of Chinese medicine, is a medical text written beginning in the 2nd century BCE and compiled in the 3rd century.[28]
+
+In India, the surgeon Sushruta described numerous surgical operations, including the earliest forms of plastic surgery.[29][dubious  – discuss][30] Earliest records of dedicated hospitals come from Mihintale in Sri Lanka where evidence of dedicated medicinal treatment facilities for patients are found.[31][32]
+
+In Greece, the Greek physician Hippocrates, the "father of modern medicine",[33][34] laid the foundation for a rational approach to medicine. Hippocrates introduced the Hippocratic Oath for physicians, which is still relevant and in use today, and was the first to categorize illnesses as acute, chronic, endemic and epidemic, and use terms such as, "exacerbation, relapse, resolution, crisis, paroxysm, peak, and convalescence".[35][36] The Greek physician Galen was also one of the greatest surgeons of the ancient world and performed many audacious operations, including brain and eye surgeries. After the fall of the Western Roman Empire and the onset of the Early Middle Ages, the Greek tradition of medicine went into decline in Western Europe, although it continued uninterrupted in the Eastern Roman (Byzantine) Empire.
+
+Most of our knowledge of ancient Hebrew medicine during the 1st millennium BC comes from the Torah, i.e. the Five Books of Moses, which contain various health related laws and rituals. The Hebrew contribution to the development of modern medicine started in the Byzantine Era, with the physician Asaph the Jew.[37]
+
+The concept of hospital as institution to offer medical care and possibility of a cure for the patients due to the ideals of Christian charity, rather than just merely a place to die, appeared in the Byzantine Empire.[38]
+
+Although the concept of uroscopy was known to Galen, he did not see the importance of using it to localize the disease. It was under the Byzantines with physicians such of Theophilus Protospatharius that they realized the potential in uroscopy to determine disease in a time when no microscope or stethoscope existed. That practice eventually spread to the rest of Europe.[39]
+
+After 750 CE, the Muslim world had the works of Hippocrates, Galen and Sushruta translated into Arabic, and Islamic physicians engaged in some significant medical research. Notable Islamic medical pioneers include the Persian polymath, Avicenna, who, along with Imhotep and Hippocrates, has also been called the "father of medicine".[40] He wrote The Canon of Medicine which became a standard medical text at many medieval European universities,[41] considered one of the most famous books in the history of medicine.[42] Others include Abulcasis,[43] Avenzoar,[44] Ibn al-Nafis,[45] and Averroes.[46] Persian  physician Rhazes[47] was one of the first to question the Greek theory of humorism, which nevertheless remained influential in both medieval Western and medieval Islamic medicine.[48] Some volumes of Rhazes's work Al-Mansuri, namely "On Surgery" and "A General Book on Therapy", became part of the medical curriculum in European universities.[49] Additionally, he has been described as a doctor's doctor,[50] the father of pediatrics,[51][52] and a pioneer of ophthalmology. For example, he was the first to recognize the reaction of the eye's pupil to light.[52] The Persian Bimaristan hospitals were an early example of public hospitals.[53][54]
+
+In Europe, Charlemagne decreed that a hospital should be attached to each cathedral and monastery and the historian Geoffrey Blainey likened the activities of the Catholic Church in health care during the Middle Ages to an early version of a welfare state: "It conducted hospitals for the old and orphanages for the young; hospices for the sick of all ages; places for the lepers; and hostels or inns where pilgrims could buy a cheap bed and meal". It supplied food to the population during famine and distributed food to the poor. This welfare system the church funded through collecting taxes on a large scale and possessing large farmlands and estates. The Benedictine order was noted for setting up hospitals and infirmaries in their monasteries, growing medical herbs and becoming the chief medical care givers of their districts, as at the great Abbey of Cluny. The Church also established a network of cathedral schools and universities where medicine was studied. The Schola Medica Salernitana in Salerno, looking to the learning of Greek and Arab physicians, grew to be the finest medical school in Medieval Europe.[55]
+
+However, the fourteenth and fifteenth century Black Death devastated both the Middle East and Europe, and it has even been argued that Western Europe was generally more effective in recovering from the pandemic than the Middle East.[56] In the early modern period, important early figures in medicine and anatomy emerged in Europe, including Gabriele Falloppio and William Harvey.
+
+The major shift in medical thinking was the gradual rejection, especially during the Black Death in the 14th and 15th centuries, of what may be called the 'traditional authority' approach to science and medicine. This was the notion that because some prominent person in the past said something must be so, then that was the way it was, and anything one observed to the contrary was an anomaly (which was paralleled by a similar shift in European society in general – see Copernicus's rejection of Ptolemy's theories on astronomy). Physicians like Vesalius improved upon or disproved some of the theories from the past. The main tomes used both by medicine students and expert physicians were Materia Medica and Pharmacopoeia.
+
+Andreas Vesalius was the author of De humani corporis fabrica, an important book on human anatomy.[57] Bacteria and microorganisms were first observed with a microscope by Antonie van Leeuwenhoek in 1676, initiating the scientific field microbiology.[58] Independently from Ibn al-Nafis, Michael Servetus rediscovered the pulmonary circulation, but this discovery did not reach the public because it was written down for the first time in the "Manuscript of Paris"[59] in 1546, and later published in the theological work for which he paid with his life in 1553. Later this was described by Renaldus Columbus and Andrea Cesalpino. Herman Boerhaave is sometimes referred to as a "father of physiology" due to his exemplary teaching in Leiden and textbook 'Institutiones medicae' (1708). Pierre Fauchard has been called "the father of modern dentistry".[60]
+
+Veterinary medicine was, for the first time, truly separated from human medicine in 1761, when the French veterinarian Claude Bourgelat founded the world's first veterinary school in Lyon, France. Before this, medical doctors treated both humans and other animals.
+
+Modern scientific biomedical research (where results are testable and reproducible) began to replace early Western traditions based on herbalism, the Greek "four humours" and other such pre-modern notions. The modern era really began with Edward Jenner's discovery of the smallpox vaccine at the end of the 18th century (inspired by the method of inoculation earlier practiced in Asia), Robert Koch's discoveries around 1880 of the transmission of disease by bacteria, and then the discovery of antibiotics around 1900.
+
+The post-18th century modernity period brought more groundbreaking researchers from Europe. From Germany and Austria, doctors Rudolf Virchow, Wilhelm Conrad Röntgen, Karl Landsteiner and Otto Loewi made notable contributions. In the United Kingdom, Alexander Fleming, Joseph Lister, Francis Crick and Florence Nightingale are considered important. Spanish doctor Santiago Ramón y Cajal is considered the father of modern neuroscience.
+
+From New Zealand and Australia came Maurice Wilkins, Howard Florey, and Frank Macfarlane Burnet.
+
+Others that did significant work include William Williams Keen, William Coley, James D. Watson (United States); Salvador Luria (Italy); Alexandre Yersin (Switzerland); Kitasato Shibasaburō (Japan); Jean-Martin Charcot, Claude Bernard, Paul Broca (France); Adolfo Lutz (Brazil); Nikolai Korotkov (Russia); Sir William Osler (Canada); and Harvey Cushing (United States).
+
+As science and technology developed, medicine became more reliant upon medications. Throughout history and in Europe right until the late 18th century, not only animal and plant products were used as medicine, but also human body parts and fluids.[61] Pharmacology developed in part from herbalism and some drugs are still derived from plants (atropine, ephedrine, warfarin, aspirin, digoxin, vinca alkaloids,[62] taxol, hyoscine, etc.).[63] Vaccines were discovered by Edward Jenner and Louis Pasteur.
+
+The first antibiotic was arsphenamine (Salvarsan) discovered by Paul Ehrlich in 1908 after he observed that bacteria took up toxic dyes that human cells did not. The first major class of antibiotics was the sulfa drugs, derived by German chemists originally from azo dyes.
+
+Pharmacology has become increasingly sophisticated; modern biotechnology allows drugs targeted towards specific physiological processes to be developed, sometimes designed for compatibility with the body to reduce side-effects. Genomics and knowledge of human genetics and human evolution is having increasingly significant influence on medicine, as the causative genes of most monogenic genetic disorders have now been identified, and the development of techniques in molecular biology, evolution, and genetics are influencing medical technology, practice and decision-making.
+
+Evidence-based medicine is a contemporary movement to establish the most effective algorithms of practice (ways of doing things) through the use of systematic reviews and meta-analysis. The movement is facilitated by modern global information science, which allows as much of the available evidence as possible to be collected and analyzed according to standard protocols that are then disseminated to healthcare providers. The Cochrane Collaboration leads this movement. A 2001 review of 160 Cochrane systematic reviews revealed that, according to two readers, 21.3% of the reviews concluded insufficient evidence, 20% concluded evidence of no effect, and 22.5% concluded positive effect.[64]
+
+Evidence-based medicine, prevention of medical error (and other "iatrogenesis"), and avoidance of unnecessary health care are a priority in modern medical systems. These topics generate significant political and public policy attention, particularly in the United States where healthcare is regarded as excessively costly but population health metrics lag similar nations.[65]
+
+Globally, many developing countries lack access to care and access to medicines.[66] As of 2015, most wealthy developed countries provide health care to all citizens, with a few exceptions such as the United States where lack of health insurance coverage may limit access.[67]
+
+The World Health Organization (WHO) defines traditional medicine as "the sum total of the knowledge, skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures, whether explicable or not, used in the maintenance of health as well as in the prevention, diagnosis, improvement or treatment of physical and mental illness."[68] Practices known as traditional medicines include Ayurveda, Siddha medicine, Unani, ancient Iranian medicine, Irani, Islamic medicine, traditional Chinese medicine, traditional Korean medicine, acupuncture, Muti, Ifá, and traditional African medicine.
+
+The WHO stated that "inappropriate use of traditional medicines or practices can have negative or dangerous effects" and that "further research is needed to ascertain the efficacy and safety" of several of the practices and medicinal plants used by traditional medicine systems.[68] As example, Indian Medical Association regard traditional medicine practices, such as Ayurveda and Siddha medicine, as quackery.[69][70][71] Practitioners of traditional medicine are not authorized to practice medicine in India unless trained at a qualified medical institution, registered with the government, and listed as registered physicians annually in The Gazette of India.[69][70] Identifying practitioners of traditional medicine, the Supreme Court of India stated in 2018 that "unqualified, untrained quacks are posing a great risk to the entire society and playing with the lives of people without having the requisite training and education in the science from approved institutions".[69]
+

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+Medicine is the science and practice of establishing the diagnosis, prognosis, treatment, and prevention of disease. Medicine encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness. Contemporary medicine applies biomedical sciences, biomedical research, genetics, and medical technology to diagnose, treat, and prevent injury and disease, typically through pharmaceuticals or surgery, but also through therapies as diverse as psychotherapy, external splints and traction, medical devices, biologics, and ionizing radiation, amongst others.[1]
+
+Medicine has been around for thousands of years, during most of which it was an art (an area of skill and knowledge) frequently having connections to the religious and philosophical beliefs of local culture. For example, a medicine man would apply herbs and say prayers for healing, or an ancient philosopher and physician would apply bloodletting according to the theories of humorism. In recent centuries, since the advent of modern science, most medicine has become a combination of art and science (both basic and applied, under the umbrella of medical science). While stitching technique for sutures is an art learned through practice, the knowledge of what happens at the cellular and molecular level in the tissues being stitched arises through science.
+
+Prescientific forms of medicine are now known as traditional medicine and folk medicine. They remain commonly used with, or instead of, scientific medicine and are thus called alternative medicine. As an example, evidence on the effectiveness of acupuncture is "variable and inconsistent" for any condition,[2] but is generally safe when done by an appropriately trained practitioner.[3] In contrast, alternative treatments outside the bounds not just of scientific medicine, but also outside the bounds of safety and efficacy are termed quackery. This can encompass an array of practices and practitioners, irrespective of whether they are prescientific (traditional medicine and folk medicine) or modern pseudo-scientific, including chiropractic which rejects modern scientific germ theory of disease (instead believing without evidence that human diseases are caused by invisible subluxation of the bones, predominantly of the spine and less so of other bones), with just over half of chiropractors also rejecting the science of immunization.
+
+Medicine (UK: /ˈmɛdsɪn/ (listen), US: /ˈmɛdɪsɪn/ (listen)) is the science and practice of the diagnosis, prognosis, treatment, and prevention of disease.[4][5] The word "medicine" is derived from Latin medicus, meaning "a physician".[6][7]
+
+Medical availability and clinical practice varies across the world due to regional differences in culture and technology. Modern scientific medicine is highly developed in the Western world, while in developing countries such as parts of Africa or Asia, the population may rely more heavily on traditional medicine with limited evidence and efficacy and no required formal training for practitioners.[8] In the developed world, evidence-based medicine is not universally used in clinical practice; for example, a 2007 survey of literature reviews found that about 49% of the interventions lacked sufficient evidence to support either benefit or harm.[9]
+
+In modern clinical practice, physicians personally assess patients in order to diagnose, prognose, treat, and prevent disease using clinical judgment. The doctor-patient relationship typically begins an interaction with an examination of the patient's medical history and medical record, followed by a medical interview[10] and a physical examination. Basic diagnostic medical devices (e.g. stethoscope, tongue depressor) are typically used. After examination for signs and interviewing for symptoms, the doctor may order medical tests (e.g. blood tests), take a biopsy, or prescribe pharmaceutical drugs or other therapies. Differential diagnosis methods help to rule out conditions based on the information provided. During the encounter, properly informing the patient of all relevant facts is an important part of the relationship and the development of trust. The medical encounter is then documented in the medical record, which is a legal document in many jurisdictions.[11] Follow-ups may be shorter but follow the same general procedure, and specialists follow a similar process. The diagnosis and treatment may take only a few minutes or a few weeks depending upon the complexity of the issue.
+
+The components of the medical interview[10] and encounter are:
+
+The physical examination is the examination of the patient for medical signs of disease, which are objective and observable, in contrast to symptoms that are volunteered by the patient and not necessarily objectively observable.[12] The healthcare provider uses sight, hearing, touch, and sometimes smell (e.g., in infection, uremia, diabetic ketoacidosis). Four actions are the basis of physical examination: inspection, palpation (feel), percussion (tap to determine resonance characteristics), and auscultation (listen), generally in that order although auscultation occurs prior to percussion and palpation for abdominal assessments.[13]
+
+The clinical examination involves the study of:
+
+It is to likely focus on areas of interest highlighted in the medical history and may not include everything listed above.
+
+The treatment plan may include ordering additional medical laboratory tests and medical imaging studies, starting therapy, referral to a specialist, or watchful observation. Follow-up may be advised. Depending upon the health insurance plan and the managed care system, various forms of "utilization review", such as prior authorization of tests, may place barriers on accessing expensive services.[14]
+
+The medical decision-making (MDM) process involves analysis and synthesis of all the above data to come up with a list of possible diagnoses (the differential diagnoses), along with an idea of what needs to be done to obtain a definitive diagnosis that would explain the patient's problem.
+
+On subsequent visits, the process may be repeated in an abbreviated manner to obtain any new history, symptoms, physical findings, and lab or imaging results or specialist consultations.
+
+Contemporary medicine is in general conducted within health care systems. Legal, credentialing and financing frameworks are established by individual governments, augmented on occasion by international organizations, such as churches. The characteristics of any given health care system have significant impact on the way medical care is provided.
+
+From ancient times, Christian emphasis on practical charity gave rise to the development of systematic nursing and hospitals and the Catholic Church today remains the largest non-government provider of medical services in the world.[15] Advanced industrial countries (with the exception of the United States)[16][17] and many developing countries provide medical services through a system of universal health care that aims to guarantee care for all through a single-payer health care system, or compulsory private or co-operative health insurance. This is intended to ensure that the entire population has access to medical care on the basis of need rather than ability to pay. Delivery may be via private medical practices or by state-owned hospitals and clinics, or by charities, most commonly by a combination of all three.
+
+Most tribal societies provide no guarantee of healthcare for the population as a whole. In such societies, healthcare is available to those that can afford to pay for it or have self-insured it (either directly or as part of an employment contract) or who may be covered by care financed by the government or tribe directly.
+
+Transparency of information is another factor defining a delivery system. Access to information on conditions, treatments, quality, and pricing greatly affects the choice by patients/consumers and, therefore, the incentives of medical professionals. While the US healthcare system has come under fire for lack of openness,[18] new legislation may encourage greater openness. There is a perceived tension between the need for transparency on the one hand and such issues as patient confidentiality and the possible exploitation of information for commercial gain on the other.
+
+Provision of medical care is classified into primary, secondary, and tertiary care categories.
+
+Primary care medical services are provided by physicians, physician assistants, nurse practitioners, or other health professionals who have first contact with a patient seeking medical treatment or care. These occur in physician offices, clinics, nursing homes, schools, home visits, and other places close to patients. About 90% of medical visits can be treated by the primary care provider. These include treatment of acute and chronic illnesses, preventive care and health education for all ages and both sexes.
+
+Secondary care medical services are provided by medical specialists in their offices or clinics or at local community hospitals for a patient referred by a primary care provider who first diagnosed or treated the patient. Referrals are made for those patients who required the expertise or procedures performed by specialists. These include both ambulatory care and inpatient services, Emergency departments, intensive care medicine, surgery services, physical therapy, labor and delivery, endoscopy units, diagnostic laboratory and medical imaging services, hospice centers, etc. Some primary care providers may also take care of hospitalized patients and deliver babies in a secondary care setting.
+
+Tertiary care medical services are provided by specialist hospitals or regional centers equipped with diagnostic and treatment facilities not generally available at local hospitals. These include trauma centers, burn treatment centers, advanced neonatology unit services, organ transplants, high-risk pregnancy, radiation oncology, etc.
+
+Modern medical care also depends on information – still delivered in many health care settings on paper records, but increasingly nowadays by electronic means.
+
+In low-income countries, modern healthcare is often too expensive for the average person. International healthcare policy researchers have advocated that "user fees" be removed in these areas to ensure access, although even after removal, significant costs and barriers remain.[19]
+
+Separation of prescribing and dispensing is a practice in medicine and pharmacy in which the physician who provides a medical prescription is independent from the  pharmacist who provides the prescription drug. In the Western world there are centuries of tradition for separating pharmacists from physicians. In Asian countries, it is traditional for physicians to also provide drugs.[20]
+
+Working together as an interdisciplinary team, many highly trained health professionals besides medical practitioners are involved in the delivery of modern health care. Examples include: nurses, emergency medical technicians and paramedics, laboratory scientists, pharmacists, podiatrists, physiotherapists, respiratory therapists, speech therapists, occupational therapists, radiographers, dietitians, and bioengineers, medical physics, surgeons, surgeon's assistant, surgical technologist.
+
+The scope and sciences underpinning human medicine overlap many other fields. Dentistry, while considered by some a separate discipline from medicine, is a medical field.
+
+A patient admitted to the hospital is usually under the care of a specific team based on their main presenting problem, e.g., the cardiology team, who then may interact with other specialties, e.g., surgical, radiology, to help diagnose or treat the main problem or any subsequent complications/developments.
+
+Physicians have many specializations and subspecializations into certain branches of medicine, which are listed below. There are variations from country to country regarding which specialties certain subspecialties are in.
+
+The main branches of medicine are:
+
+In the broadest meaning of "medicine", there are many different specialties. In the UK, most specialities have their own body or college, which has its own entrance examination. These are collectively known as the Royal Colleges, although not all currently use the term "Royal". The development of a speciality is often driven by new technology (such as the development of effective anaesthetics) or ways of working (such as emergency departments); the new specialty leads to the formation of a unifying body of doctors and the prestige of administering their own examination.
+
+Within medical circles, specialities usually fit into one of two broad categories: "Medicine" and "Surgery." "Medicine" refers to the practice of non-operative medicine, and most of its subspecialties require preliminary training in Internal Medicine. In the UK, this was traditionally evidenced by passing the examination for the Membership of the Royal College of Physicians (MRCP) or the equivalent college in Scotland or Ireland. "Surgery" refers to the practice of operative medicine, and most subspecialties in this area require preliminary training in General Surgery, which in the UK leads to membership of the Royal College of Surgeons of England (MRCS). At present, some specialties of medicine do not fit easily into either of these categories, such as radiology, pathology, or anesthesia. Most of these have branched from one or other of the two camps above; for example anaesthesia developed first as a faculty of the Royal College of Surgeons (for which MRCS/FRCS would have been required) before becoming the Royal College of Anaesthetists and membership of the college is attained by sitting for the examination of the Fellowship of the Royal College of Anesthetists (FRCA).
+
+Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate or treat a pathological condition such as disease or injury, to help improve bodily function or appearance or to repair unwanted ruptured areas (for example, a perforated ear drum). Surgeons must also manage pre-operative, post-operative, and potential surgical candidates on the hospital wards. Surgery has many sub-specialties, including general surgery, ophthalmic surgery, cardiovascular surgery, colorectal surgery, neurosurgery, oral and maxillofacial surgery, oncologic surgery, orthopedic surgery, otolaryngology, plastic surgery, podiatric surgery, transplant surgery, trauma surgery, urology, vascular surgery, and pediatric surgery. In some centers, anesthesiology is part of the division of surgery (for historical and logistical reasons), although it is not a surgical discipline. Other medical specialties may employ surgical procedures, such as ophthalmology and dermatology, but are not considered surgical sub-specialties per se.
+
+Surgical training in the U.S. requires a minimum of five years of residency after medical school. Sub-specialties of surgery often require seven or more years. In addition, fellowships can last an additional one to three years. Because post-residency fellowships can be competitive, many trainees devote two additional years to research. Thus in some cases surgical training will not finish until more than a decade after medical school. Furthermore, surgical training can be very difficult and time-consuming.
+
+Internal medicine is the medical specialty dealing with the prevention, diagnosis, and treatment of adult diseases. According to some sources, an emphasis on internal structures is implied.[21] In North America, specialists in internal medicine are commonly called "internists." Elsewhere, especially in Commonwealth nations, such specialists are often called physicians.[22] These terms, internist or physician (in the narrow sense, common outside North America), generally exclude practitioners of gynecology and obstetrics, pathology, psychiatry, and especially surgery and its subspecialities.
+
+Because their patients are often seriously ill or require complex investigations, internists do much of their work in hospitals. Formerly, many internists were not subspecialized; such general physicians would see any complex nonsurgical problem; this style of practice has become much less common. In modern urban practice, most internists are subspecialists: that is, they generally limit their medical practice to problems of one organ system or to one particular area of medical knowledge. For example, gastroenterologists and nephrologists specialize respectively in diseases of the gut and the kidneys.[23]
+
+In the Commonwealth of Nations and some other countries, specialist pediatricians and geriatricians are also described as specialist physicians (or internists) who have subspecialized by age of patient rather than by organ system. Elsewhere, especially in North America, general pediatrics is often a form of primary care.
+
+There are many subspecialities (or subdisciplines) of internal medicine:
+
+Training in internal medicine (as opposed to surgical training), varies considerably across the world: see the articles on medical education and physician for more details. In North America, it requires at least three years of residency training after medical school, which can then be followed by a one- to three-year fellowship in the subspecialties listed above. In general, resident work hours in medicine are less than those in surgery, averaging about 60 hours per week in the US. This difference does not apply in the UK where all doctors are now required by law to work less than 48 hours per week on average.
+
+The following are some major medical specialties that do not directly fit into any of the above-mentioned groups:
+
+Some interdisciplinary sub-specialties of medicine include:
+
+Medical education and training varies around the world. It typically involves entry level education at a university medical school, followed by a period of supervised practice or internship, or residency. This can be followed by postgraduate vocational training. A variety of teaching methods have been employed in medical education, still itself a focus of active research. In Canada and the United States of America, a Doctor of Medicine degree, often abbreviated M.D., or a Doctor of Osteopathic Medicine degree, often abbreviated as D.O. and unique to the United States, must be completed in and delivered from a recognized university.
+
+Since knowledge, techniques, and medical technology continue to evolve at a rapid rate, many regulatory authorities require continuing medical education. Medical practitioners upgrade their knowledge in various ways, including medical journals, seminars, conferences, and online programs.  A database of objectives covering medical knowledge, as suggested by national societies across the United States, can be searched at http://data.medobjectives.marian.edu/.[25]
+
+In most countries, it is a legal requirement for a medical doctor to be licensed or registered. In general, this entails a medical degree from a university and accreditation by a medical board or an equivalent national organization, which may ask the applicant to pass exams. This restricts the considerable legal authority of the medical profession to physicians that are trained and qualified by national standards. It is also intended as an assurance to patients and as a safeguard against charlatans that practice inadequate medicine for personal gain. While the laws generally require medical doctors to be trained in "evidence based", Western, or Hippocratic Medicine, they are not intended to discourage different paradigms of health.
+
+In the European Union, the profession of doctor of medicine is regulated. A profession is said to be regulated when access and exercise is subject to the possession of a specific professional qualification.
+The regulated professions database contains a list of regulated professions for doctor of medicine in the EU member states, EEA countries and Switzerland. This list is covered by the Directive 2005/36/EC.
+
+Doctors who are negligent or intentionally harmful in their care of patients can face charges of medical malpractice and be subject to civil, criminal, or professional sanctions.
+
+Medical ethics is a system of moral principles that apply values and judgments to the practice of medicine. As a scholarly discipline, medical ethics encompasses its practical application in clinical settings as well as work on its history, philosophy, theology, and sociology. Six of the values that commonly apply to medical ethics discussions are:
+
+Values such as these do not give answers as to how to handle a particular situation, but provide a useful framework for understanding conflicts. When moral values are in conflict, the result may be an ethical dilemma or crisis. Sometimes, no good solution to a dilemma in medical ethics exists, and occasionally, the values of the medical community (i.e., the hospital and its staff) conflict with the values of the individual patient, family, or larger non-medical community. Conflicts can also arise between health care providers, or among family members. For example, some argue that the principles of autonomy and beneficence clash when patients refuse blood transfusions, considering them life-saving; and truth-telling was not emphasized to a large extent before the HIV era.
+
+Prehistoric medicine incorporated plants (herbalism), animal parts, and minerals. In many cases these materials were used ritually as magical substances by priests, shamans, or medicine men. Well-known spiritual systems include animism (the notion of inanimate objects having spirits), spiritualism (an appeal to gods or communion with ancestor spirits); shamanism (the vesting of an individual with mystic powers); and divination (magically obtaining the truth). The field of medical anthropology examines the ways in which culture and society are organized around or impacted by issues of health, health care and related issues.
+
+Early records on medicine have been discovered from ancient Egyptian medicine, Babylonian Medicine, Ayurvedic medicine (in the Indian subcontinent), classical Chinese medicine (predecessor to the modern traditional Chinese medicine), and ancient Greek medicine and Roman medicine.
+
+In Egypt, Imhotep (3rd millennium BCE) is the first physician in history known by name. The oldest Egyptian medical text is the Kahun Gynaecological Papyrus from around 2000 BCE, which describes gynaecological diseases. The Edwin Smith Papyrus dating back to 1600 BCE is an early work on surgery, while the Ebers Papyrus dating back to 1500 BCE is akin to a textbook on medicine.[26]
+
+In China, archaeological evidence of medicine in Chinese dates back to the Bronze Age Shang Dynasty, based on seeds for herbalism and tools presumed to have been used for surgery.[27] The Huangdi Neijing, the progenitor of Chinese medicine, is a medical text written beginning in the 2nd century BCE and compiled in the 3rd century.[28]
+
+In India, the surgeon Sushruta described numerous surgical operations, including the earliest forms of plastic surgery.[29][dubious  – discuss][30] Earliest records of dedicated hospitals come from Mihintale in Sri Lanka where evidence of dedicated medicinal treatment facilities for patients are found.[31][32]
+
+In Greece, the Greek physician Hippocrates, the "father of modern medicine",[33][34] laid the foundation for a rational approach to medicine. Hippocrates introduced the Hippocratic Oath for physicians, which is still relevant and in use today, and was the first to categorize illnesses as acute, chronic, endemic and epidemic, and use terms such as, "exacerbation, relapse, resolution, crisis, paroxysm, peak, and convalescence".[35][36] The Greek physician Galen was also one of the greatest surgeons of the ancient world and performed many audacious operations, including brain and eye surgeries. After the fall of the Western Roman Empire and the onset of the Early Middle Ages, the Greek tradition of medicine went into decline in Western Europe, although it continued uninterrupted in the Eastern Roman (Byzantine) Empire.
+
+Most of our knowledge of ancient Hebrew medicine during the 1st millennium BC comes from the Torah, i.e. the Five Books of Moses, which contain various health related laws and rituals. The Hebrew contribution to the development of modern medicine started in the Byzantine Era, with the physician Asaph the Jew.[37]
+
+The concept of hospital as institution to offer medical care and possibility of a cure for the patients due to the ideals of Christian charity, rather than just merely a place to die, appeared in the Byzantine Empire.[38]
+
+Although the concept of uroscopy was known to Galen, he did not see the importance of using it to localize the disease. It was under the Byzantines with physicians such of Theophilus Protospatharius that they realized the potential in uroscopy to determine disease in a time when no microscope or stethoscope existed. That practice eventually spread to the rest of Europe.[39]
+
+After 750 CE, the Muslim world had the works of Hippocrates, Galen and Sushruta translated into Arabic, and Islamic physicians engaged in some significant medical research. Notable Islamic medical pioneers include the Persian polymath, Avicenna, who, along with Imhotep and Hippocrates, has also been called the "father of medicine".[40] He wrote The Canon of Medicine which became a standard medical text at many medieval European universities,[41] considered one of the most famous books in the history of medicine.[42] Others include Abulcasis,[43] Avenzoar,[44] Ibn al-Nafis,[45] and Averroes.[46] Persian  physician Rhazes[47] was one of the first to question the Greek theory of humorism, which nevertheless remained influential in both medieval Western and medieval Islamic medicine.[48] Some volumes of Rhazes's work Al-Mansuri, namely "On Surgery" and "A General Book on Therapy", became part of the medical curriculum in European universities.[49] Additionally, he has been described as a doctor's doctor,[50] the father of pediatrics,[51][52] and a pioneer of ophthalmology. For example, he was the first to recognize the reaction of the eye's pupil to light.[52] The Persian Bimaristan hospitals were an early example of public hospitals.[53][54]
+
+In Europe, Charlemagne decreed that a hospital should be attached to each cathedral and monastery and the historian Geoffrey Blainey likened the activities of the Catholic Church in health care during the Middle Ages to an early version of a welfare state: "It conducted hospitals for the old and orphanages for the young; hospices for the sick of all ages; places for the lepers; and hostels or inns where pilgrims could buy a cheap bed and meal". It supplied food to the population during famine and distributed food to the poor. This welfare system the church funded through collecting taxes on a large scale and possessing large farmlands and estates. The Benedictine order was noted for setting up hospitals and infirmaries in their monasteries, growing medical herbs and becoming the chief medical care givers of their districts, as at the great Abbey of Cluny. The Church also established a network of cathedral schools and universities where medicine was studied. The Schola Medica Salernitana in Salerno, looking to the learning of Greek and Arab physicians, grew to be the finest medical school in Medieval Europe.[55]
+
+However, the fourteenth and fifteenth century Black Death devastated both the Middle East and Europe, and it has even been argued that Western Europe was generally more effective in recovering from the pandemic than the Middle East.[56] In the early modern period, important early figures in medicine and anatomy emerged in Europe, including Gabriele Falloppio and William Harvey.
+
+The major shift in medical thinking was the gradual rejection, especially during the Black Death in the 14th and 15th centuries, of what may be called the 'traditional authority' approach to science and medicine. This was the notion that because some prominent person in the past said something must be so, then that was the way it was, and anything one observed to the contrary was an anomaly (which was paralleled by a similar shift in European society in general – see Copernicus's rejection of Ptolemy's theories on astronomy). Physicians like Vesalius improved upon or disproved some of the theories from the past. The main tomes used both by medicine students and expert physicians were Materia Medica and Pharmacopoeia.
+
+Andreas Vesalius was the author of De humani corporis fabrica, an important book on human anatomy.[57] Bacteria and microorganisms were first observed with a microscope by Antonie van Leeuwenhoek in 1676, initiating the scientific field microbiology.[58] Independently from Ibn al-Nafis, Michael Servetus rediscovered the pulmonary circulation, but this discovery did not reach the public because it was written down for the first time in the "Manuscript of Paris"[59] in 1546, and later published in the theological work for which he paid with his life in 1553. Later this was described by Renaldus Columbus and Andrea Cesalpino. Herman Boerhaave is sometimes referred to as a "father of physiology" due to his exemplary teaching in Leiden and textbook 'Institutiones medicae' (1708). Pierre Fauchard has been called "the father of modern dentistry".[60]
+
+Veterinary medicine was, for the first time, truly separated from human medicine in 1761, when the French veterinarian Claude Bourgelat founded the world's first veterinary school in Lyon, France. Before this, medical doctors treated both humans and other animals.
+
+Modern scientific biomedical research (where results are testable and reproducible) began to replace early Western traditions based on herbalism, the Greek "four humours" and other such pre-modern notions. The modern era really began with Edward Jenner's discovery of the smallpox vaccine at the end of the 18th century (inspired by the method of inoculation earlier practiced in Asia), Robert Koch's discoveries around 1880 of the transmission of disease by bacteria, and then the discovery of antibiotics around 1900.
+
+The post-18th century modernity period brought more groundbreaking researchers from Europe. From Germany and Austria, doctors Rudolf Virchow, Wilhelm Conrad Röntgen, Karl Landsteiner and Otto Loewi made notable contributions. In the United Kingdom, Alexander Fleming, Joseph Lister, Francis Crick and Florence Nightingale are considered important. Spanish doctor Santiago Ramón y Cajal is considered the father of modern neuroscience.
+
+From New Zealand and Australia came Maurice Wilkins, Howard Florey, and Frank Macfarlane Burnet.
+
+Others that did significant work include William Williams Keen, William Coley, James D. Watson (United States); Salvador Luria (Italy); Alexandre Yersin (Switzerland); Kitasato Shibasaburō (Japan); Jean-Martin Charcot, Claude Bernard, Paul Broca (France); Adolfo Lutz (Brazil); Nikolai Korotkov (Russia); Sir William Osler (Canada); and Harvey Cushing (United States).
+
+As science and technology developed, medicine became more reliant upon medications. Throughout history and in Europe right until the late 18th century, not only animal and plant products were used as medicine, but also human body parts and fluids.[61] Pharmacology developed in part from herbalism and some drugs are still derived from plants (atropine, ephedrine, warfarin, aspirin, digoxin, vinca alkaloids,[62] taxol, hyoscine, etc.).[63] Vaccines were discovered by Edward Jenner and Louis Pasteur.
+
+The first antibiotic was arsphenamine (Salvarsan) discovered by Paul Ehrlich in 1908 after he observed that bacteria took up toxic dyes that human cells did not. The first major class of antibiotics was the sulfa drugs, derived by German chemists originally from azo dyes.
+
+Pharmacology has become increasingly sophisticated; modern biotechnology allows drugs targeted towards specific physiological processes to be developed, sometimes designed for compatibility with the body to reduce side-effects. Genomics and knowledge of human genetics and human evolution is having increasingly significant influence on medicine, as the causative genes of most monogenic genetic disorders have now been identified, and the development of techniques in molecular biology, evolution, and genetics are influencing medical technology, practice and decision-making.
+
+Evidence-based medicine is a contemporary movement to establish the most effective algorithms of practice (ways of doing things) through the use of systematic reviews and meta-analysis. The movement is facilitated by modern global information science, which allows as much of the available evidence as possible to be collected and analyzed according to standard protocols that are then disseminated to healthcare providers. The Cochrane Collaboration leads this movement. A 2001 review of 160 Cochrane systematic reviews revealed that, according to two readers, 21.3% of the reviews concluded insufficient evidence, 20% concluded evidence of no effect, and 22.5% concluded positive effect.[64]
+
+Evidence-based medicine, prevention of medical error (and other "iatrogenesis"), and avoidance of unnecessary health care are a priority in modern medical systems. These topics generate significant political and public policy attention, particularly in the United States where healthcare is regarded as excessively costly but population health metrics lag similar nations.[65]
+
+Globally, many developing countries lack access to care and access to medicines.[66] As of 2015, most wealthy developed countries provide health care to all citizens, with a few exceptions such as the United States where lack of health insurance coverage may limit access.[67]
+
+The World Health Organization (WHO) defines traditional medicine as "the sum total of the knowledge, skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures, whether explicable or not, used in the maintenance of health as well as in the prevention, diagnosis, improvement or treatment of physical and mental illness."[68] Practices known as traditional medicines include Ayurveda, Siddha medicine, Unani, ancient Iranian medicine, Irani, Islamic medicine, traditional Chinese medicine, traditional Korean medicine, acupuncture, Muti, Ifá, and traditional African medicine.
+
+The WHO stated that "inappropriate use of traditional medicines or practices can have negative or dangerous effects" and that "further research is needed to ascertain the efficacy and safety" of several of the practices and medicinal plants used by traditional medicine systems.[68] As example, Indian Medical Association regard traditional medicine practices, such as Ayurveda and Siddha medicine, as quackery.[69][70][71] Practitioners of traditional medicine are not authorized to practice medicine in India unless trained at a qualified medical institution, registered with the government, and listed as registered physicians annually in The Gazette of India.[69][70] Identifying practitioners of traditional medicine, the Supreme Court of India stated in 2018 that "unqualified, untrained quacks are posing a great risk to the entire society and playing with the lives of people without having the requisite training and education in the science from approved institutions".[69]
+

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+Medicine is the science and practice of establishing the diagnosis, prognosis, treatment, and prevention of disease. Medicine encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness. Contemporary medicine applies biomedical sciences, biomedical research, genetics, and medical technology to diagnose, treat, and prevent injury and disease, typically through pharmaceuticals or surgery, but also through therapies as diverse as psychotherapy, external splints and traction, medical devices, biologics, and ionizing radiation, amongst others.[1]
+
+Medicine has been around for thousands of years, during most of which it was an art (an area of skill and knowledge) frequently having connections to the religious and philosophical beliefs of local culture. For example, a medicine man would apply herbs and say prayers for healing, or an ancient philosopher and physician would apply bloodletting according to the theories of humorism. In recent centuries, since the advent of modern science, most medicine has become a combination of art and science (both basic and applied, under the umbrella of medical science). While stitching technique for sutures is an art learned through practice, the knowledge of what happens at the cellular and molecular level in the tissues being stitched arises through science.
+
+Prescientific forms of medicine are now known as traditional medicine and folk medicine. They remain commonly used with, or instead of, scientific medicine and are thus called alternative medicine. As an example, evidence on the effectiveness of acupuncture is "variable and inconsistent" for any condition,[2] but is generally safe when done by an appropriately trained practitioner.[3] In contrast, alternative treatments outside the bounds not just of scientific medicine, but also outside the bounds of safety and efficacy are termed quackery. This can encompass an array of practices and practitioners, irrespective of whether they are prescientific (traditional medicine and folk medicine) or modern pseudo-scientific, including chiropractic which rejects modern scientific germ theory of disease (instead believing without evidence that human diseases are caused by invisible subluxation of the bones, predominantly of the spine and less so of other bones), with just over half of chiropractors also rejecting the science of immunization.
+
+Medicine (UK: /ˈmɛdsɪn/ (listen), US: /ˈmɛdɪsɪn/ (listen)) is the science and practice of the diagnosis, prognosis, treatment, and prevention of disease.[4][5] The word "medicine" is derived from Latin medicus, meaning "a physician".[6][7]
+
+Medical availability and clinical practice varies across the world due to regional differences in culture and technology. Modern scientific medicine is highly developed in the Western world, while in developing countries such as parts of Africa or Asia, the population may rely more heavily on traditional medicine with limited evidence and efficacy and no required formal training for practitioners.[8] In the developed world, evidence-based medicine is not universally used in clinical practice; for example, a 2007 survey of literature reviews found that about 49% of the interventions lacked sufficient evidence to support either benefit or harm.[9]
+
+In modern clinical practice, physicians personally assess patients in order to diagnose, prognose, treat, and prevent disease using clinical judgment. The doctor-patient relationship typically begins an interaction with an examination of the patient's medical history and medical record, followed by a medical interview[10] and a physical examination. Basic diagnostic medical devices (e.g. stethoscope, tongue depressor) are typically used. After examination for signs and interviewing for symptoms, the doctor may order medical tests (e.g. blood tests), take a biopsy, or prescribe pharmaceutical drugs or other therapies. Differential diagnosis methods help to rule out conditions based on the information provided. During the encounter, properly informing the patient of all relevant facts is an important part of the relationship and the development of trust. The medical encounter is then documented in the medical record, which is a legal document in many jurisdictions.[11] Follow-ups may be shorter but follow the same general procedure, and specialists follow a similar process. The diagnosis and treatment may take only a few minutes or a few weeks depending upon the complexity of the issue.
+
+The components of the medical interview[10] and encounter are:
+
+The physical examination is the examination of the patient for medical signs of disease, which are objective and observable, in contrast to symptoms that are volunteered by the patient and not necessarily objectively observable.[12] The healthcare provider uses sight, hearing, touch, and sometimes smell (e.g., in infection, uremia, diabetic ketoacidosis). Four actions are the basis of physical examination: inspection, palpation (feel), percussion (tap to determine resonance characteristics), and auscultation (listen), generally in that order although auscultation occurs prior to percussion and palpation for abdominal assessments.[13]
+
+The clinical examination involves the study of:
+
+It is to likely focus on areas of interest highlighted in the medical history and may not include everything listed above.
+
+The treatment plan may include ordering additional medical laboratory tests and medical imaging studies, starting therapy, referral to a specialist, or watchful observation. Follow-up may be advised. Depending upon the health insurance plan and the managed care system, various forms of "utilization review", such as prior authorization of tests, may place barriers on accessing expensive services.[14]
+
+The medical decision-making (MDM) process involves analysis and synthesis of all the above data to come up with a list of possible diagnoses (the differential diagnoses), along with an idea of what needs to be done to obtain a definitive diagnosis that would explain the patient's problem.
+
+On subsequent visits, the process may be repeated in an abbreviated manner to obtain any new history, symptoms, physical findings, and lab or imaging results or specialist consultations.
+
+Contemporary medicine is in general conducted within health care systems. Legal, credentialing and financing frameworks are established by individual governments, augmented on occasion by international organizations, such as churches. The characteristics of any given health care system have significant impact on the way medical care is provided.
+
+From ancient times, Christian emphasis on practical charity gave rise to the development of systematic nursing and hospitals and the Catholic Church today remains the largest non-government provider of medical services in the world.[15] Advanced industrial countries (with the exception of the United States)[16][17] and many developing countries provide medical services through a system of universal health care that aims to guarantee care for all through a single-payer health care system, or compulsory private or co-operative health insurance. This is intended to ensure that the entire population has access to medical care on the basis of need rather than ability to pay. Delivery may be via private medical practices or by state-owned hospitals and clinics, or by charities, most commonly by a combination of all three.
+
+Most tribal societies provide no guarantee of healthcare for the population as a whole. In such societies, healthcare is available to those that can afford to pay for it or have self-insured it (either directly or as part of an employment contract) or who may be covered by care financed by the government or tribe directly.
+
+Transparency of information is another factor defining a delivery system. Access to information on conditions, treatments, quality, and pricing greatly affects the choice by patients/consumers and, therefore, the incentives of medical professionals. While the US healthcare system has come under fire for lack of openness,[18] new legislation may encourage greater openness. There is a perceived tension between the need for transparency on the one hand and such issues as patient confidentiality and the possible exploitation of information for commercial gain on the other.
+
+Provision of medical care is classified into primary, secondary, and tertiary care categories.
+
+Primary care medical services are provided by physicians, physician assistants, nurse practitioners, or other health professionals who have first contact with a patient seeking medical treatment or care. These occur in physician offices, clinics, nursing homes, schools, home visits, and other places close to patients. About 90% of medical visits can be treated by the primary care provider. These include treatment of acute and chronic illnesses, preventive care and health education for all ages and both sexes.
+
+Secondary care medical services are provided by medical specialists in their offices or clinics or at local community hospitals for a patient referred by a primary care provider who first diagnosed or treated the patient. Referrals are made for those patients who required the expertise or procedures performed by specialists. These include both ambulatory care and inpatient services, Emergency departments, intensive care medicine, surgery services, physical therapy, labor and delivery, endoscopy units, diagnostic laboratory and medical imaging services, hospice centers, etc. Some primary care providers may also take care of hospitalized patients and deliver babies in a secondary care setting.
+
+Tertiary care medical services are provided by specialist hospitals or regional centers equipped with diagnostic and treatment facilities not generally available at local hospitals. These include trauma centers, burn treatment centers, advanced neonatology unit services, organ transplants, high-risk pregnancy, radiation oncology, etc.
+
+Modern medical care also depends on information – still delivered in many health care settings on paper records, but increasingly nowadays by electronic means.
+
+In low-income countries, modern healthcare is often too expensive for the average person. International healthcare policy researchers have advocated that "user fees" be removed in these areas to ensure access, although even after removal, significant costs and barriers remain.[19]
+
+Separation of prescribing and dispensing is a practice in medicine and pharmacy in which the physician who provides a medical prescription is independent from the  pharmacist who provides the prescription drug. In the Western world there are centuries of tradition for separating pharmacists from physicians. In Asian countries, it is traditional for physicians to also provide drugs.[20]
+
+Working together as an interdisciplinary team, many highly trained health professionals besides medical practitioners are involved in the delivery of modern health care. Examples include: nurses, emergency medical technicians and paramedics, laboratory scientists, pharmacists, podiatrists, physiotherapists, respiratory therapists, speech therapists, occupational therapists, radiographers, dietitians, and bioengineers, medical physics, surgeons, surgeon's assistant, surgical technologist.
+
+The scope and sciences underpinning human medicine overlap many other fields. Dentistry, while considered by some a separate discipline from medicine, is a medical field.
+
+A patient admitted to the hospital is usually under the care of a specific team based on their main presenting problem, e.g., the cardiology team, who then may interact with other specialties, e.g., surgical, radiology, to help diagnose or treat the main problem or any subsequent complications/developments.
+
+Physicians have many specializations and subspecializations into certain branches of medicine, which are listed below. There are variations from country to country regarding which specialties certain subspecialties are in.
+
+The main branches of medicine are:
+
+In the broadest meaning of "medicine", there are many different specialties. In the UK, most specialities have their own body or college, which has its own entrance examination. These are collectively known as the Royal Colleges, although not all currently use the term "Royal". The development of a speciality is often driven by new technology (such as the development of effective anaesthetics) or ways of working (such as emergency departments); the new specialty leads to the formation of a unifying body of doctors and the prestige of administering their own examination.
+
+Within medical circles, specialities usually fit into one of two broad categories: "Medicine" and "Surgery." "Medicine" refers to the practice of non-operative medicine, and most of its subspecialties require preliminary training in Internal Medicine. In the UK, this was traditionally evidenced by passing the examination for the Membership of the Royal College of Physicians (MRCP) or the equivalent college in Scotland or Ireland. "Surgery" refers to the practice of operative medicine, and most subspecialties in this area require preliminary training in General Surgery, which in the UK leads to membership of the Royal College of Surgeons of England (MRCS). At present, some specialties of medicine do not fit easily into either of these categories, such as radiology, pathology, or anesthesia. Most of these have branched from one or other of the two camps above; for example anaesthesia developed first as a faculty of the Royal College of Surgeons (for which MRCS/FRCS would have been required) before becoming the Royal College of Anaesthetists and membership of the college is attained by sitting for the examination of the Fellowship of the Royal College of Anesthetists (FRCA).
+
+Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate or treat a pathological condition such as disease or injury, to help improve bodily function or appearance or to repair unwanted ruptured areas (for example, a perforated ear drum). Surgeons must also manage pre-operative, post-operative, and potential surgical candidates on the hospital wards. Surgery has many sub-specialties, including general surgery, ophthalmic surgery, cardiovascular surgery, colorectal surgery, neurosurgery, oral and maxillofacial surgery, oncologic surgery, orthopedic surgery, otolaryngology, plastic surgery, podiatric surgery, transplant surgery, trauma surgery, urology, vascular surgery, and pediatric surgery. In some centers, anesthesiology is part of the division of surgery (for historical and logistical reasons), although it is not a surgical discipline. Other medical specialties may employ surgical procedures, such as ophthalmology and dermatology, but are not considered surgical sub-specialties per se.
+
+Surgical training in the U.S. requires a minimum of five years of residency after medical school. Sub-specialties of surgery often require seven or more years. In addition, fellowships can last an additional one to three years. Because post-residency fellowships can be competitive, many trainees devote two additional years to research. Thus in some cases surgical training will not finish until more than a decade after medical school. Furthermore, surgical training can be very difficult and time-consuming.
+
+Internal medicine is the medical specialty dealing with the prevention, diagnosis, and treatment of adult diseases. According to some sources, an emphasis on internal structures is implied.[21] In North America, specialists in internal medicine are commonly called "internists." Elsewhere, especially in Commonwealth nations, such specialists are often called physicians.[22] These terms, internist or physician (in the narrow sense, common outside North America), generally exclude practitioners of gynecology and obstetrics, pathology, psychiatry, and especially surgery and its subspecialities.
+
+Because their patients are often seriously ill or require complex investigations, internists do much of their work in hospitals. Formerly, many internists were not subspecialized; such general physicians would see any complex nonsurgical problem; this style of practice has become much less common. In modern urban practice, most internists are subspecialists: that is, they generally limit their medical practice to problems of one organ system or to one particular area of medical knowledge. For example, gastroenterologists and nephrologists specialize respectively in diseases of the gut and the kidneys.[23]
+
+In the Commonwealth of Nations and some other countries, specialist pediatricians and geriatricians are also described as specialist physicians (or internists) who have subspecialized by age of patient rather than by organ system. Elsewhere, especially in North America, general pediatrics is often a form of primary care.
+
+There are many subspecialities (or subdisciplines) of internal medicine:
+
+Training in internal medicine (as opposed to surgical training), varies considerably across the world: see the articles on medical education and physician for more details. In North America, it requires at least three years of residency training after medical school, which can then be followed by a one- to three-year fellowship in the subspecialties listed above. In general, resident work hours in medicine are less than those in surgery, averaging about 60 hours per week in the US. This difference does not apply in the UK where all doctors are now required by law to work less than 48 hours per week on average.
+
+The following are some major medical specialties that do not directly fit into any of the above-mentioned groups:
+
+Some interdisciplinary sub-specialties of medicine include:
+
+Medical education and training varies around the world. It typically involves entry level education at a university medical school, followed by a period of supervised practice or internship, or residency. This can be followed by postgraduate vocational training. A variety of teaching methods have been employed in medical education, still itself a focus of active research. In Canada and the United States of America, a Doctor of Medicine degree, often abbreviated M.D., or a Doctor of Osteopathic Medicine degree, often abbreviated as D.O. and unique to the United States, must be completed in and delivered from a recognized university.
+
+Since knowledge, techniques, and medical technology continue to evolve at a rapid rate, many regulatory authorities require continuing medical education. Medical practitioners upgrade their knowledge in various ways, including medical journals, seminars, conferences, and online programs.  A database of objectives covering medical knowledge, as suggested by national societies across the United States, can be searched at http://data.medobjectives.marian.edu/.[25]
+
+In most countries, it is a legal requirement for a medical doctor to be licensed or registered. In general, this entails a medical degree from a university and accreditation by a medical board or an equivalent national organization, which may ask the applicant to pass exams. This restricts the considerable legal authority of the medical profession to physicians that are trained and qualified by national standards. It is also intended as an assurance to patients and as a safeguard against charlatans that practice inadequate medicine for personal gain. While the laws generally require medical doctors to be trained in "evidence based", Western, or Hippocratic Medicine, they are not intended to discourage different paradigms of health.
+
+In the European Union, the profession of doctor of medicine is regulated. A profession is said to be regulated when access and exercise is subject to the possession of a specific professional qualification.
+The regulated professions database contains a list of regulated professions for doctor of medicine in the EU member states, EEA countries and Switzerland. This list is covered by the Directive 2005/36/EC.
+
+Doctors who are negligent or intentionally harmful in their care of patients can face charges of medical malpractice and be subject to civil, criminal, or professional sanctions.
+
+Medical ethics is a system of moral principles that apply values and judgments to the practice of medicine. As a scholarly discipline, medical ethics encompasses its practical application in clinical settings as well as work on its history, philosophy, theology, and sociology. Six of the values that commonly apply to medical ethics discussions are:
+
+Values such as these do not give answers as to how to handle a particular situation, but provide a useful framework for understanding conflicts. When moral values are in conflict, the result may be an ethical dilemma or crisis. Sometimes, no good solution to a dilemma in medical ethics exists, and occasionally, the values of the medical community (i.e., the hospital and its staff) conflict with the values of the individual patient, family, or larger non-medical community. Conflicts can also arise between health care providers, or among family members. For example, some argue that the principles of autonomy and beneficence clash when patients refuse blood transfusions, considering them life-saving; and truth-telling was not emphasized to a large extent before the HIV era.
+
+Prehistoric medicine incorporated plants (herbalism), animal parts, and minerals. In many cases these materials were used ritually as magical substances by priests, shamans, or medicine men. Well-known spiritual systems include animism (the notion of inanimate objects having spirits), spiritualism (an appeal to gods or communion with ancestor spirits); shamanism (the vesting of an individual with mystic powers); and divination (magically obtaining the truth). The field of medical anthropology examines the ways in which culture and society are organized around or impacted by issues of health, health care and related issues.
+
+Early records on medicine have been discovered from ancient Egyptian medicine, Babylonian Medicine, Ayurvedic medicine (in the Indian subcontinent), classical Chinese medicine (predecessor to the modern traditional Chinese medicine), and ancient Greek medicine and Roman medicine.
+
+In Egypt, Imhotep (3rd millennium BCE) is the first physician in history known by name. The oldest Egyptian medical text is the Kahun Gynaecological Papyrus from around 2000 BCE, which describes gynaecological diseases. The Edwin Smith Papyrus dating back to 1600 BCE is an early work on surgery, while the Ebers Papyrus dating back to 1500 BCE is akin to a textbook on medicine.[26]
+
+In China, archaeological evidence of medicine in Chinese dates back to the Bronze Age Shang Dynasty, based on seeds for herbalism and tools presumed to have been used for surgery.[27] The Huangdi Neijing, the progenitor of Chinese medicine, is a medical text written beginning in the 2nd century BCE and compiled in the 3rd century.[28]
+
+In India, the surgeon Sushruta described numerous surgical operations, including the earliest forms of plastic surgery.[29][dubious  – discuss][30] Earliest records of dedicated hospitals come from Mihintale in Sri Lanka where evidence of dedicated medicinal treatment facilities for patients are found.[31][32]
+
+In Greece, the Greek physician Hippocrates, the "father of modern medicine",[33][34] laid the foundation for a rational approach to medicine. Hippocrates introduced the Hippocratic Oath for physicians, which is still relevant and in use today, and was the first to categorize illnesses as acute, chronic, endemic and epidemic, and use terms such as, "exacerbation, relapse, resolution, crisis, paroxysm, peak, and convalescence".[35][36] The Greek physician Galen was also one of the greatest surgeons of the ancient world and performed many audacious operations, including brain and eye surgeries. After the fall of the Western Roman Empire and the onset of the Early Middle Ages, the Greek tradition of medicine went into decline in Western Europe, although it continued uninterrupted in the Eastern Roman (Byzantine) Empire.
+
+Most of our knowledge of ancient Hebrew medicine during the 1st millennium BC comes from the Torah, i.e. the Five Books of Moses, which contain various health related laws and rituals. The Hebrew contribution to the development of modern medicine started in the Byzantine Era, with the physician Asaph the Jew.[37]
+
+The concept of hospital as institution to offer medical care and possibility of a cure for the patients due to the ideals of Christian charity, rather than just merely a place to die, appeared in the Byzantine Empire.[38]
+
+Although the concept of uroscopy was known to Galen, he did not see the importance of using it to localize the disease. It was under the Byzantines with physicians such of Theophilus Protospatharius that they realized the potential in uroscopy to determine disease in a time when no microscope or stethoscope existed. That practice eventually spread to the rest of Europe.[39]
+
+After 750 CE, the Muslim world had the works of Hippocrates, Galen and Sushruta translated into Arabic, and Islamic physicians engaged in some significant medical research. Notable Islamic medical pioneers include the Persian polymath, Avicenna, who, along with Imhotep and Hippocrates, has also been called the "father of medicine".[40] He wrote The Canon of Medicine which became a standard medical text at many medieval European universities,[41] considered one of the most famous books in the history of medicine.[42] Others include Abulcasis,[43] Avenzoar,[44] Ibn al-Nafis,[45] and Averroes.[46] Persian  physician Rhazes[47] was one of the first to question the Greek theory of humorism, which nevertheless remained influential in both medieval Western and medieval Islamic medicine.[48] Some volumes of Rhazes's work Al-Mansuri, namely "On Surgery" and "A General Book on Therapy", became part of the medical curriculum in European universities.[49] Additionally, he has been described as a doctor's doctor,[50] the father of pediatrics,[51][52] and a pioneer of ophthalmology. For example, he was the first to recognize the reaction of the eye's pupil to light.[52] The Persian Bimaristan hospitals were an early example of public hospitals.[53][54]
+
+In Europe, Charlemagne decreed that a hospital should be attached to each cathedral and monastery and the historian Geoffrey Blainey likened the activities of the Catholic Church in health care during the Middle Ages to an early version of a welfare state: "It conducted hospitals for the old and orphanages for the young; hospices for the sick of all ages; places for the lepers; and hostels or inns where pilgrims could buy a cheap bed and meal". It supplied food to the population during famine and distributed food to the poor. This welfare system the church funded through collecting taxes on a large scale and possessing large farmlands and estates. The Benedictine order was noted for setting up hospitals and infirmaries in their monasteries, growing medical herbs and becoming the chief medical care givers of their districts, as at the great Abbey of Cluny. The Church also established a network of cathedral schools and universities where medicine was studied. The Schola Medica Salernitana in Salerno, looking to the learning of Greek and Arab physicians, grew to be the finest medical school in Medieval Europe.[55]
+
+However, the fourteenth and fifteenth century Black Death devastated both the Middle East and Europe, and it has even been argued that Western Europe was generally more effective in recovering from the pandemic than the Middle East.[56] In the early modern period, important early figures in medicine and anatomy emerged in Europe, including Gabriele Falloppio and William Harvey.
+
+The major shift in medical thinking was the gradual rejection, especially during the Black Death in the 14th and 15th centuries, of what may be called the 'traditional authority' approach to science and medicine. This was the notion that because some prominent person in the past said something must be so, then that was the way it was, and anything one observed to the contrary was an anomaly (which was paralleled by a similar shift in European society in general – see Copernicus's rejection of Ptolemy's theories on astronomy). Physicians like Vesalius improved upon or disproved some of the theories from the past. The main tomes used both by medicine students and expert physicians were Materia Medica and Pharmacopoeia.
+
+Andreas Vesalius was the author of De humani corporis fabrica, an important book on human anatomy.[57] Bacteria and microorganisms were first observed with a microscope by Antonie van Leeuwenhoek in 1676, initiating the scientific field microbiology.[58] Independently from Ibn al-Nafis, Michael Servetus rediscovered the pulmonary circulation, but this discovery did not reach the public because it was written down for the first time in the "Manuscript of Paris"[59] in 1546, and later published in the theological work for which he paid with his life in 1553. Later this was described by Renaldus Columbus and Andrea Cesalpino. Herman Boerhaave is sometimes referred to as a "father of physiology" due to his exemplary teaching in Leiden and textbook 'Institutiones medicae' (1708). Pierre Fauchard has been called "the father of modern dentistry".[60]
+
+Veterinary medicine was, for the first time, truly separated from human medicine in 1761, when the French veterinarian Claude Bourgelat founded the world's first veterinary school in Lyon, France. Before this, medical doctors treated both humans and other animals.
+
+Modern scientific biomedical research (where results are testable and reproducible) began to replace early Western traditions based on herbalism, the Greek "four humours" and other such pre-modern notions. The modern era really began with Edward Jenner's discovery of the smallpox vaccine at the end of the 18th century (inspired by the method of inoculation earlier practiced in Asia), Robert Koch's discoveries around 1880 of the transmission of disease by bacteria, and then the discovery of antibiotics around 1900.
+
+The post-18th century modernity period brought more groundbreaking researchers from Europe. From Germany and Austria, doctors Rudolf Virchow, Wilhelm Conrad Röntgen, Karl Landsteiner and Otto Loewi made notable contributions. In the United Kingdom, Alexander Fleming, Joseph Lister, Francis Crick and Florence Nightingale are considered important. Spanish doctor Santiago Ramón y Cajal is considered the father of modern neuroscience.
+
+From New Zealand and Australia came Maurice Wilkins, Howard Florey, and Frank Macfarlane Burnet.
+
+Others that did significant work include William Williams Keen, William Coley, James D. Watson (United States); Salvador Luria (Italy); Alexandre Yersin (Switzerland); Kitasato Shibasaburō (Japan); Jean-Martin Charcot, Claude Bernard, Paul Broca (France); Adolfo Lutz (Brazil); Nikolai Korotkov (Russia); Sir William Osler (Canada); and Harvey Cushing (United States).
+
+As science and technology developed, medicine became more reliant upon medications. Throughout history and in Europe right until the late 18th century, not only animal and plant products were used as medicine, but also human body parts and fluids.[61] Pharmacology developed in part from herbalism and some drugs are still derived from plants (atropine, ephedrine, warfarin, aspirin, digoxin, vinca alkaloids,[62] taxol, hyoscine, etc.).[63] Vaccines were discovered by Edward Jenner and Louis Pasteur.
+
+The first antibiotic was arsphenamine (Salvarsan) discovered by Paul Ehrlich in 1908 after he observed that bacteria took up toxic dyes that human cells did not. The first major class of antibiotics was the sulfa drugs, derived by German chemists originally from azo dyes.
+
+Pharmacology has become increasingly sophisticated; modern biotechnology allows drugs targeted towards specific physiological processes to be developed, sometimes designed for compatibility with the body to reduce side-effects. Genomics and knowledge of human genetics and human evolution is having increasingly significant influence on medicine, as the causative genes of most monogenic genetic disorders have now been identified, and the development of techniques in molecular biology, evolution, and genetics are influencing medical technology, practice and decision-making.
+
+Evidence-based medicine is a contemporary movement to establish the most effective algorithms of practice (ways of doing things) through the use of systematic reviews and meta-analysis. The movement is facilitated by modern global information science, which allows as much of the available evidence as possible to be collected and analyzed according to standard protocols that are then disseminated to healthcare providers. The Cochrane Collaboration leads this movement. A 2001 review of 160 Cochrane systematic reviews revealed that, according to two readers, 21.3% of the reviews concluded insufficient evidence, 20% concluded evidence of no effect, and 22.5% concluded positive effect.[64]
+
+Evidence-based medicine, prevention of medical error (and other "iatrogenesis"), and avoidance of unnecessary health care are a priority in modern medical systems. These topics generate significant political and public policy attention, particularly in the United States where healthcare is regarded as excessively costly but population health metrics lag similar nations.[65]
+
+Globally, many developing countries lack access to care and access to medicines.[66] As of 2015, most wealthy developed countries provide health care to all citizens, with a few exceptions such as the United States where lack of health insurance coverage may limit access.[67]
+
+The World Health Organization (WHO) defines traditional medicine as "the sum total of the knowledge, skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures, whether explicable or not, used in the maintenance of health as well as in the prevention, diagnosis, improvement or treatment of physical and mental illness."[68] Practices known as traditional medicines include Ayurveda, Siddha medicine, Unani, ancient Iranian medicine, Irani, Islamic medicine, traditional Chinese medicine, traditional Korean medicine, acupuncture, Muti, Ifá, and traditional African medicine.
+
+The WHO stated that "inappropriate use of traditional medicines or practices can have negative or dangerous effects" and that "further research is needed to ascertain the efficacy and safety" of several of the practices and medicinal plants used by traditional medicine systems.[68] As example, Indian Medical Association regard traditional medicine practices, such as Ayurveda and Siddha medicine, as quackery.[69][70][71] Practitioners of traditional medicine are not authorized to practice medicine in India unless trained at a qualified medical institution, registered with the government, and listed as registered physicians annually in The Gazette of India.[69][70] Identifying practitioners of traditional medicine, the Supreme Court of India stated in 2018 that "unqualified, untrained quacks are posing a great risk to the entire society and playing with the lives of people without having the requisite training and education in the science from approved institutions".[69]
+

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+Medellín (Spanish pronunciation: [meðeˈʝin] or [meðeˈʎin]), officially the Municipality of Medellín (Spanish: Municipio de Medellín), is the second-largest city in Colombia, after Bogotá, and the capital of the department of Antioquia. It is located in the Aburrá Valley, a central region of the Andes Mountains in South America. According to the National Administrative Department of Statistics, the city had an estimated population of 2,508,452 according to the 2018 census.[1] With its surrounding area that includes nine other cities, the metropolitan area of Medellín is the second-largest urban agglomeration in Colombia in terms of population and economy, with more than 3.7 million people.
+
+In 1616 the Spaniard Francisco Herrera Campuzano erected a small indigenous village ("poblado") known as "Saint Lawrence of Aburrá" (San Lorenzo de Aburrá), located in the present-day El Poblado commune. On 2 November 1675, the queen consort Mariana of Austria founded the "Town of Our Lady of Candelaria of Medellín" (Villa de Nuestra Señora de la Candelaria de Medellín) in the Aná region, which today corresponds to the center of the city (east-central zone) and first describes the region as "Medellín". In 1826, the city was named the capital of the Department of Antioquia by the National Congress of the nascent Republic of Gran Colombia, comprised by present-day Colombia, Venezuela, Ecuador, and Panama. After Colombia won its independence from Spain, Medellín became the capital of the Federal State of Antioquia until 1888, with the proclamation of the Colombian Constitution of 1886. During the 19th century, Medellín was a dynamic commercial center, first exporting gold, then producing and exporting coffee.
+
+At the beginning of the 21st century, the city regained industrial dynamism, with the construction of the Medellín Metro commuter rail, liberalized development policies, improved security and improved education. Researchers at the Overseas Development Institute have lauded the city as a pioneer of a post-Washington consensus "local development state" model of economic development.[4]  The city is promoted internationally as a tourist destination and is considered a global city type "Gamma -" by GaWC.[5] The Medellín Metropolitan Area produces 67% of the Department of Antioquia's GDP and 11% of the economy of Colombia.[6] Medellín is important to the region for its universities, academies, commerce, industry, science, health services, flower-growing, and festivals.
+
+In February 2013, the Urban Land Institute chose Medellín as the most innovative city in the world due to its recent advances in politics, education and social development.[7] In the same year, Medellín won the Verónica Rudge Urbanism Award conferred by Harvard University to the Urban Development Enterprise, mainly due to the North-Western Integral Development Project in the city.[8] In September 2013, the United Nations ratified Colombia's petition to host UN-Habitat's 7th World Urban Forum[9] in Medellín, from April 5–11, 2014.[10] In 2016, Medellín won the Lee Kuan Yew World City Prize. The award seeks to recognize and celebrate efforts in furthering innovation in urban solutions and sustainable urban development.[11][12]
+
+The valley and its Spanish settlement have gone by several names over the years, including Aburrá de los Yamesíes, "Valley of Saint Bartholomew", "Saint Lawrence of Aburrá", "Saint Lawrence of Aná", Villa de la Candelaria de Medellín, and finally "Medellín".[13]
+
+The name "Medellín" comes from Medellín, Spain, a small village in the Badajoz province of Extremadura. The village is known for being the birthplace of Hernán Cortés. The Spanish Medellín, in turn, was originally called "Metellinum" and was named after the Roman General Quintus Caecilius Metellus Pius in 75 BC who founded the village as a military base.[14]
+
+Some of the Conquistadors, such as Gaspar de Rodas, the first governor of Antioquia, came from the region of Badajoz. Count Pedro Portocarrero y Luna, President of the Council for the West Indies (Consejo de Indias), asked the Spanish monarchy to give the name of his town, Medellín in Extremadura, to the new settlement in America. His request was accepted on November 22, 1674, when the Regent Mariana of Austria proclaimed the city's name to be Villa de Nuestra Señora de Medellín. Miguel Aguinaga y Mendiogoitia, Governor, made the name official on November 2, 1675. The Crown granted a coat of arms to the city on June 24, 1676.[14]
+
+In August 1541, Marshal Jorge Robledo was in the place known today as Heliconia when he saw in the distance what he thought was a valley. He sent Jerónimo Luis Tejelo to explore the territory, and during the night of August 23, Tejelo reached the plain of what is now Aburrá Valley. The Spaniards gave it the name of "Valley of Saint Bartholomew", but this was soon changed for the native name Aburrá, meaning "Painters", due to the textile decorations of the local chief-men.[15]
+
+In 1574, Gaspar de Rodas asked the Antioquia's Cabildo for 10 square kilometers (4 sq mi) of land to establish herds and a ranch in the valley. The Cabildo granted him 8 square kilometers (3 sq mi) of land.[15]
+
+In 1616, the colonial visitor Francisco de Herrera y Campuzano founded a settlement with 80 Amerindians, naming it Poblado de San Lorenzo, today "El Poblado". In 1646 a colonial law ordered the separation of Amerindians from mestizos and mulattos, so the colonial administration began the construction of a new town in Aná, today Berrío Park, where the church of Nuestra Señora de la Candelaria de Aná ("Our Lady of Candelaria of Aná") was built. Three years later, the Spaniards started the construction of the Basilica of Our Lady of Candelaria, which was rebuilt at the end of the 18th century.[15]
+
+After 1574, with Gaspar de Rodas settled in the valley, the population started to grow. According to the church records of the San Lorenzo Church, six couples married between 1646 and 1650, and 41 between 1671 and 1675.[15] Gold mines were developed northeast of Antioquia, thus they needed food supply from nearby agriculture. The Aburrá Valley was in a strategic position between the gold mines and the first provincial capital of Antioquia, Santa Fe de Antioquia.[15]
+
+The provincial capital, Santa Fe, started to lose importance and gradually became poor, as trade and prominent personalities of the region came to the Aburrá Valley, where rich families started to buy land. Soon, the first settlers asked for the creation of a Cabildo (council) in the valley, thus getting a separate government from Santa Fe.[15] The Santa Fe government fought this, but Mariana of Austria signed the edict creating the Cabildo on November 22, 1674. The governor Miguel de Aguinaga proclaimed the royal edict on 2 November 1675. The new city was given the title of Villa de Nuestra Señora de la Candelaria.[15]
+
+Before the creation of the town, the inhabitants were scattered throughout the valley, with only a few families concentrated at the confluence of the Aná (today called the Santa Elena) and the Medellín rivers; others lived in El Poblado San Lorenzo. After the royal edict, the settlers chose the Aná site as the heart of the future city, with the Candelaria Church at its center.[citation needed]
+
+Their first buildings were simple, with thatched roofs. The houses of the most important people were two stories tall, and the church and the Cabildo were unimpressive. It was only during the 18th century that the church was improved. Only one story, the Cabildo was located at the western part of the plaza. It had a thatched roof until 1742 when tiles were put on. In 1682, traders and foreigners started the construction of the Veracruz Hermitage, which was consecrated as a church by the Bishop of Popayán in 1712.[15]
+
+In 1675, the first census during colonial times was taken: there were 3,000 people and 280 families. Another census was not taken until the colonial Visitador (royal inspector) Antonio Mon y Velarde ordered one between 1786 and 1787: there were then 14,507 people and 241 families. In 1808, two years before Colombia won independence, the city had 15,347 people and 360 families.[15]
+
+In 1803, the Royal College of the Franciscans was founded in the Central Plaza, which is Berrío Park today, with the initial departments of Grammar, Philosophy, and Theology.[16] Soon after, the college moved to a new building in the small San Ignacio square. In 1821 it was renamed Colegio de Antioquia, and it became the University of Antioquia in 1901. The University also had the first vocational training school, the first cultural radio station in Latin America, and the first regional botanical garden.
+
+In the first half of the twentieth century, the population of Medellín increased sixfold, from 59,815 inhabitants in 1905 to 358,189 in 1951. The Thousand Days War (1899–1902) stopped the industrial development of the city, although the civil war did not affect the region directly. Under reforms by President Rafael Reyes after the conflict, the city continued its industrial development[15] and founded a Chamber of commerce.  The Chamber developed a regional transport project that connected Medellín to other Colombian regions and other nations.
+
+Despite the importance of gold production in the early development of Medellín, the export of coffee contributed the most impetus in the 20th century for the city's growth. Trade grew to international dimensions as the main export of Colombia became coffee. The industrial and commercial dynamism of Medellín also created a caste of traders and entrepreneurs, who founded the first nationwide industries in Colombia.[15]
+
+Coltejer is one of the most important textile companies in Colombia. It was founded in Medellín by Alejandro Echavarría on October 22, 1907.[17] Its headquarters, the Coltejer Building, is the tallest skyscraper in Medellín and the fourth tallest building in Colombia.
+
+The discovery of coal in Amagá, a few kilometers south of the Aburrá Valley, and the building of hydroelectric plants provided the new industries with energy, and this allowed the creation of many smaller companies. The Antioquia Railway (built in 1875) conquered the difficult geography of one of the most mountainous regions of South America, notably with the La Quiebra Tunnel, which connected the industrial center to the Magdalena River, the most major navigable river in Colombia. In 1932 Medellín also built its first airport, the Enrique Olaya Herrera Airport.[15]
+
+The study by Charles H. Savage on industrial production in Antioquia between 1960 and 1972 showed how important Medellín industries became to Colombia and South America. He studied social change produced by the introduction of new technology. Savage looked at three factories in Antioquia: two potteries in Santuario and La Blanca, and a tailoring factory in Medellín. Savage studied the production of the Antioquian factories, and the relationship between the workers and their employers, an industrial efficiency which he called the "Culture of Work".[18] His conclusions were published by his colleague George F. Lombardi as Sons of the Machine (1988).[19][20]
+
+Arts and literature have been an important social element in Medellín. The University of Antioquia, the National University of Colombia with its Medellín branch, and the Pontifical Bolivarian University have historically been the academic centers of the city and are responsible for the formation of an intellectual class in the region.
+
+During the first part of the 20th century, the city was part of the literary transition from romanticism to the modern art and literary movements of the new century.[citation needed] The writer Tomás Carrasquilla (1858–1940)  focused on the people of his native Antioquia, portraying their daily lives and customs. The writer and philosopher Fernando González from Envigado (in the metropolitan area of Medellín), the cartoonist Ricardo Rendón and the poet León de Greiff were some of the founders of Los Panidas, a Medellín literary movement. Other featured poets and writers were Porfirio Barba-Jacob and Efe Gómez. In painting, the most famous were Eladio Vélez and Pedro Nel Gómez. Carlos Vieco Ortiz was a popular composer and musician. Medellín became the headquarters of record labels like Sonolux, Ondina and Silver.[15]
+
+Medellín clubs, many of them dating to the end of the 19th century became a center for intellectual and industrialist movements, like Club Union (founded in 1894) and Club Campestre (founded in 1924). In 1909 the Circo España was created, and Bolívar Theater, in 1919. The Junín Theater was demolished to build the Coltejer Tower. Cine Colombia, the first movie distributor of the country, was founded in Medellín in 1927.[15]
+
+Colombia entered a new era of political instability with the murder of presidential candidate Jorge Eliecer Gaitán in Bogotá in 1948. Political violence spread in the rural areas of Colombia, and farmers fled to the cities.[21] The Valley slopes became overpopulated with slums.
+
+As the population of Medellín grew quickly during the 1950s, industrialists, traders and local government created the "Medellín Master Plan" (MMP) (Plan Piloto), a plan for the expansion of the city into the Aburrá Valley that would lead to the creation of the first metropolitan area in Colombia. Paul Lester Wiener and José Luis Sert were the architects who led the project. Among the main features of the MMP were the canalization of the Medellín River, the control of new settlements on valley slopes, the creation of an industrial zone in the Guayabal District, the planning of the city to be in harmony with the river, the construction of a city stadium, and an administrative center in La Alpujarra.[15]
+
+In 1951 the city had 358,189 inhabitants, but 22 years later, in 1973, the population had tripled to 1,071,252.[22] The population explosion had several consequences for the MMP. The urban limits of the city grew to areas that were not contemplated in the MMP, so that Medellín now reached the urban areas of other cities of the Aburrá Valley, like Envigado, Bello and Itagüí; the new Medellín settlers were poor families without enough credit to buy their own homes, so several neighborhoods were built beyond the MMP; several old downtown buildings were demolished to construct tall towers, offices, and avenues.
+
+In 1968 the Second Conference of CELAM was held in Medellin expessing a preferential option for the poor. The traditional Junin Theatre along the Santa Elena was demolished to build the Coltejer Tower. The huge migration into Medellín provided workers for the expansion of textile factories, being modernized in this period,[15] but it also created new problems for the city: higher unemployment, lack of services for poor areas, urban violence in several districts, and collapse of any hope of a transport system.[citation needed]
+
+The position of Medellín as the second industrial city in Colombia has been the main factor in overcoming its crisis of the 1980s and 1990s. The Medellín Metro, a massive urban transport service, became the pride of the city, and so far the only sign of the Medellín Master Plan of the 1950s. The construction of the Plaza Mayor of Medellín, an international center for congresses and expositions, was designed to showcase the globalized economy of Colombia to the world.
+
+Social exclusion has eased due to the development of a transport infrastructure; the Metro, a new system of public buses, is being planned with the so-called "Metroplus", already inaugurated, and gondolas called “MetroCable” in the poorest barrio communities.[4] Additionally, an electric escalator 1,260 feet long was inaugurated on December 26, 2011, in Comuna 13, one of Medellín's poorest neighborhoods, making it one of the first of its kind in the world. Today's Medellín includes spaces for art, poetry, drama, the construction of public libraries, the foundation of new ecological parks, and the inclusion of people of the city in its development.[23]
+
+The city administration has pursued policies that have been lauded by researchers at the Overseas Development Institute as helping pioneer a post-Washington consensus 'local development state' model of economic development.[4]
+
+In 2012, Medellín was among 200 cities around the world, including New York and Tel Aviv, nominated for Most Innovative City of the Year due to a great advancement in public transportation, with more than 500,000 residents and visitors using its Metro train system each day; a public bike-share program; new facilities and landmarks, including the España Library and a cultural center in Moravia; a large outdoor escalator the size of a 28-story building, enabling residents of the city’s elevated Comuna 13 neighborhood to safely ride down the steep hillside; and a Metro system which reduces Medellín’s CO2 emissions by 175,000 tons each year.[24] Medellín has the biggest research-dedicated building in Colombia called University Research Building (Spanish: Sede de Investigación Universitaria, SIU)[25] a facility that concentrates the top research groups of the University of Antioquia.[26]
+
+Medellín has 16 comunas (districts), 5 corregimientos (townships), and 271 barrios (neighborhoods).
+The metropolitan area of Medellín lies within the Aburrá valley at an elevation of 1,500 metres (4,900 feet) above sea level and is bisected by the Medellín River (also called Porce), which flows northward. North of the valley are the towns of Bello, Copacabana, Girardota and Barbosa. To the south of the valley lie Itagüí, Envigado, Sabaneta, La Estrella and Caldas.
+
+The weather in Medellín is warm year-round with few temperature extremes. As a municipality, Medellín has an area of 382 km2 (147 sq mi).  Medellín features a trade-wind tropical rainforest climate (Af), albeit a noticeably cooler version of this climate that borders closely on a subtropical highland climate (Cfb) and also on a tropical monsoon climate (Am). Because Medellín is located at 1,500 m (4,900 ft) above sea level, its climate is not as hot as other cities located at the same latitude near the equator. Because of its altitude above sea level and privileged location in the Andes Range, Medellín's weather at times is more characteristic of a humid subtropical climate than that of a tropical climate. The city's average annual temperature is 22 °C (72 °F), and because of its proximity to the equator, its temperature is constant year-round, with minimal temperature variations. Temperatures range from 15 to 30 °C (59 to 86 °F). Because of the pleasant springlike climate all year, Medellín is known as "La Ciudad de la Eterna Primavera" or "City of the Eternal Spring". However, as the city is located in a valley and many of its districts are on slopes, temperatures can be slightly cooler on the surrounding mountains.
+
+Medellín is a city governed by a republican democratic system as stated in the Colombian Constitution of 1991, with decentralized government. Administration is shared by the Mayor of Medellín and the Municipal Council, both elected by popular vote.
+The municipality is made up of official departments (secretarías) including departments for social mobility, urban culture, social development, education, evaluation and control, government, resources, public works, administrative services, environment, women, and transportation. There are also many departments with a certain autonomy: the Olaya Herrera Airport, the Public Library (Biblioteca Pública Piloto), the College of Antioquia (Colegio Mayor), the Urban Development Enterprise (EDU), the Public Service Enterprise (EPM), the Sport and Recreation Institute (INDER), the General Enterprises of Medellín (EEVVM), the Medellín Bus stations, the General Hospital of Medellín, the health service enterprise "Metrosalud", the Metropolitan Institute of Technology (ITM), the Metro de Medellín, the Department for the Administration of the Medellín parks (Metroparques) and Metroseguridad.
+
+The municipality is divided into six zones: The urban zone, which is subdivided into 16 comunas (communes).  The communes are further divided into 249 statistical neighborhoods. The remaining zones outside the urban zones comprise five corregimientos (townships).
+
+Further, the municipality belongs to the Medellín Metropolitan Area, which is made up of ten neighboring municipalities.
+
+The government of the city of Medellín is divided into executive and legislative branches. The mayor of the city (Alcalde) is publicly elected for a term of four years (just like the president and the governor of any other department in Colombia).
+
+Low tax rates mean Medellín's city administration's social and economic development policies have been funded by the city's ownership of the main energy supplier, Empresas Publicas de Medellín (EPM); 30% of its profits go directly to the city's administrative budget.[4] In addition to infrastructure projects, the city administration has developed a program of cash grants called 'the Medellín Solidaria' programme that is very similar to Brazil's highly successful Bolsa Familia and also the city runs the Cultura E programme.[4]
+
+According to the city administration, Medellín Solidaria represents an improvement on Colombia's national programme, 'Familias en Accion' (Families in Action).[4] The city administration is further responsible for coordinating more than 100 other social programmes.[4] Under the Cultura E programme, the city administration has established a network of 14 publicly funded business support centres known as CEDEZO, Centros de Desarrollo Empresarial Zonal).[4] The CEDEZOs are found in the poorest areas of Medellín and support the poor in developing business by providing free-of-charge business support services and technical advice.[4]
+
+Also, as part of Cultura E, there is Banco de las Oportunidades that provides microloans (up to $2,500 at a cheap interest rate of 0.91% monthly).[4] This has helped create more equal opportunities for all and overcome the barriers to entry to business for poor entrepreneurs with good ideas, but lacking capital, skills and connections.[4] It has also helped develop the local economy with new micro-enterprises.[4]
+
+However, several mayoral candidates for the October 2011 elections have argued the Banco de las Oportunidades's interest rates are too high, loan maturity is too short and it should have grace periods.[4] They, therefore, suggest a new small and medium-sized enterprise (SME) development bank to complement the Banco de las Oportunidades.
+
+Medellín was once known as the most dangerous city in the world,[30][31] a result of an urban war set off by the drug cartels at the end of the 1980s. As the home of the Medellín Cartel funded by Pablo Escobar, the city was a victim of the terror caused by the war between the organization headed by Escobar, and competing organizations such as "El Cartel del Valle". However, after the death of Escobar, crime rates in the city have decreased dramatically.[32]
+
+Throughout the rest of the 1990s crime rates remained relatively high, although gradually declining from the worst years.  In October 2002, President Álvaro Uribe ordered the military to carry out "Operation Orion", the objective of which was to disband the urban militias of the FARC and the AUC.[32] Between 2003 and 2006 the demobilization of the remaining urban militias of the AUC was completed, with more than 3,000 armed men giving up their weapons.[33]
+
+Nonetheless, after the disbanding of the main paramilitary groups, many members of such organizations have been known to have reorganized into criminal bands known commonly as Aguilas Negras ("Black Eagles"). These groups have gained notoriety in Medellín for calling upon curfews for the underage population, and have been known to distribute fliers announcing the social cleansing of prostitutes, drug addicts, and alcoholics.[34] The extradition of paramilitary leader Don Berna appears to have sparked a crime wave with a sharp increase in killings.[35]
+
+As home of the now defunct Medellín Cartel, the city was once known as the most violent city in the world.[30] However, its homicide rate has decreased by 95% and extreme poverty by 66%, thanks in part to a string of innovative mayors who laid out plans to integrate the poorest and most violent hillside neighborhoods into the city center in the valley below. Medellín is now considered safer than the US cities of Baltimore, St. Louis, Detroit and New Orleans, which appear in the CCSPJP's top 50 list.[36]
+
+There is a significant disparity in crime rates by neighborhoods, with virtually no homicides in El Poblado to areas with open gunfights in the outskirts. Generally, crime rates increase the further the neighborhood is from the center.[37] From 2010 and 2011, homicides have declined as with crime in general, but there remains a high crime rate in the poorest communities.
+
+3.2 percent of street addresses account for 97 percent of homicides.[38] More than half of the violent deaths are attributed to clashes between criminal gangs in certain parts of the city. In 1991 there were 7,273 murders at a rate of 266 per 100,000 people; in 2017 had suffered 577 murders at a rate of 23 per 100,000 inhabitants. In the city there are more than 1,100 security cameras and more than 7,000 policemen.[39][40]
+
+Medellín is one of Colombia's economic centers. Its economy is led by a powerful group of people from the private sector known as the Grupo Empresarial Antioqueño (Antioquian Enterprises Group). The group was formerly known as the Sindicato Antioqueño (Antioquian Union) but after being mistaken abroad for a labor union, which hampered its international growth for many years, a new formal name was chosen. It is represented by David Bojanini, head of Grupo Suramericana (a banking, asset management and insurance conglomerate); Carlos Ignacio Gallego of Grupo Nutresa (food industry); José Alberto Velez of Cementos Argos (a multinational cement company); and Carlos Raúl Yepes, head of Bancolombia. This group has an aggregate market capitalization of approximately US $17 billion and employs more than 80,000 Colombians.[41]
+
+This group also participates in other sectors of the city industry and is an active trader in the Colombian stock exchange. Medellín serves as headquarters for many national and multinational companies.
+
+Medellín's main economic products are steel, textiles, confections, food and beverage, agriculture (from its rural area), public services, chemical products, pharmaceuticals, refined oil, and flowers. Fashion is a major part of the economy and culture of the city. Medellín hosts Latin America's biggest fashion show, Colombiamoda.
+
+Aerolínea de Antioquia has its headquarters on the grounds of Enrique Olaya Herrera Airport in Medellín.[42] West Caribbean Airways had its headquarters on the grounds of Olaya Herrera Airport.[43] ACES Colombia was headquartered in the city.[44] VivaColombia, the only low-cost Colombian airline, has its hub at Rionegro's Airport.
+
+The Metropolitan Area of Medellín contributes 67% of the total GDP of the Department of Antioquia and 11% of the economy of Colombia.[6] Antioquia is the second-greatest economic region of Colombia. By 2005, Antioquia's GDP was more than US$14,700,000,000 and the top exporting province in Colombia.[46] The Aburrá Valley is the top economy in the province, and its GDP was $7,800 million.[6] Medellín is the second-largest economic region in Colombia, after Bogotá.
+
+The 2005 Report of the Economic Colombian Review of Proexport and the International Cooperation Agency of Medellín concluded that Medellín was at the same level of GDP contribution to the national economy as cities like Panama City in Panama, and San José de Costa Rica.
+
+Medellín created the first Colombian business cluster. The city is the top exporting region of the country, with 1,750 export businesses based in Medellín.[46] The Cluster was created with the support of the Chamber of Commerce of Medellín and the City Administration for an actual total of 21,000 companies that share 40% of total exports, 25% of the regional GDP, and 40% of Metro Area employment.[46] The main economic activities of the Medellín Cluster (MC) are in electricity generation, textile, fashion design, construction, tourism and business.[47] One goal of the Medellín Cluster is to include health services, an important sector in the local economy.
+
+Ruta N is a non-profit in Medellín which helps foreign companies set up office in Medellín.
+
+According to data released by the Measuring Monetary Poverty and Inequality Mission (Spanish: Misión para el Empalme de las Series de Empleo, Pobreza y Desigualdad, MESEP), in November 2009, the poverty rate in Medellín and its metropolitan area was reduced by 22.5%, from 49.7% to 38.5% during the period from 2002 to 2008. Similarly, the extreme poverty rate decreased by 25.2%, from 12.3% to 9.2%. These results are in line with the increased coverage of basic services such as health, education, and public services in the city. In 2014, the poverty rate decreased to 14.7% and extreme poverty to 2.8%.[48]
+
+The unemployment rate in Medellín and its metropolitan area, as has been the case in Colombia as a whole, has decreased in the past decade. According to data from the National Statistics Department (Spanish: Departamento Administrativo Nacional de Estadística, DANE) unemployment for Medellín and its Metropolitan Area was reduced by 25%, from 14.1%,[49] just above the national average of 13.9% in 2005 to 10.6%,[50] above the national average of 9.9%, in 2015. However, according to DANE, in 2014 Medellín stood out as one of the most unequal cities of Colombia, with a GINI coefficient of 0.506.[48]
+
+There are signs of heavy urban development within the city of Medellín, particularly with the construction of new skyscrapers. Medellín is outpacing all other major Colombian cities, including Bogotá, in the construction and proposed development of new high-rises. As of October 2016, there were 10 skyscrapers, 410 high-rises, 119 buildings under construction in Medellín, including 48 being planned.[51] Other projects that the city has planned are extensions of the cities metro system to nearby suburbs such as Sabaneta. Under construction, the new project is set to open to the public soon.
+
+Medellín was awarded 2013 "Innovative City of the Year" by the Wall Street Journal[52] on March 1 after beating out New York City and Tel Aviv.[53]
+
+When Sergio Fajardo became Mayor of Medellín in 2004, the "Medellín, Commitment of all the Citizens" plan for the city was enacted. One of its fundamental axes was described as "Social Urbanism".[54] The final objective of this model was to promote peace and social equity through its urban policies. To accomplish this, priority was given to the areas of the city where bigger social and economic issues were found. The main tool used with this objective was the planning and development of urban projects that would transform the physical environment while promoting profound social and cultural shifts in the communities they were implemented.[55]
+
+The projects were identified and prioritized using six main guidelines as described in the City Plan by the Council of Medellín:[56]
+
+The main objective of these projects is to fight inequity and exclusion. The neighborhoods with the biggest inequity and violence issues are identified and important investments are made in them. There is no previous agenda over what the specific nature of the interventions will finally be since the projects use a communicative approach to define what is best for the community with the active participation of its members.[56] The outcomes will depend on what the neighborhood decides supported by the inclusion of the expertise of city organizations. The projects will have to incorporate all the elements needed to foster development and will be executed simultaneously to assure the biggest impact.
+
+Aside from usual city investment in public infrastructure and as a result of this approach to city development, there were four main concrete projects that were established to help achieve the objectives of peace and social equity based on the guidelines proposed in the Medellín City Plan by the Council of Medellín.[56]
+
+A "library park" (Spanish: Parque biblioteca) is a term first used in Medellín for an urban complex formed by a combination of a library building with ample surrounding green space for public use. These library parks are strategically located in the periphery of the city to address the need for more cultural and education space and public services in less affluent neighborhoods.[57] The development of library complexes and schools is part of an effort at cultural transformation.[58] This project also aims to create centralities inside the intervened areas that help consolidate and give a clearer identity to the communities. They are meant to provide a network of activity centers for the promotion of education, culture, sport, and recreation.
+
+The initial plan in 2009 built five libraries with attached parks to serve underprivileged neighborhoods. This development included the Biblioteca Parque España designed by Giancarlo Mazzanti,.[59][60] and which was named after Spain, who helped fund the construction of one of its buildings. Architects of the other libraries added as part of the program include Ricardo La Rotta Caballero and Hiroshi Naito. The four other libraries added were León de Greiff Library (also known as La Ladera Library Park), San Javier Library Park, Bethlehem Library Park, and La Quintana Library Park.
+
+After the initial 2009 program another five libraries were added to the plan for 2011. These libraries are the Doce de Octubre Library Park for Comunas 5 and 6, Noroccidente; Las Estancias Library Park for Comunas 8, 9, and Centroriental; Parque Biblioteca Guayabal for Comuna 15 and Suroccidente; Parque Biblioteca San Cristóbal] for Corregimiento and Occidente; and Parque Biblioteca San Antonio de Prado for Corregimiento and Sur.[61]
+
+The idea of "library parks" has served as a model for library spaces in other countries, most notably the Manguinhos Library Park in Rio de Janeiro, Brazil.
+
+The Medellín Metropolitan Area Library Network is a set of libraries linked together to share resources, efforts, knowledge and experience to improve the educational and cultural conditions of the community. The network consists of over 100 libraries, 29 of which reside in Medellín.[62] The Library Network includes all of Medellín's library parks, as well as other regional libraries, such as the Public Pilot Library and the EPM Library.
+
+The Library Network was a program created as a metropolitan agreement in 2005 thanks to an alliance of Empresas Públicas de Medellín, its EPM Foundation, the Mayor of Medellín, and the Pilot Public Library. In 2009, the Library Network was awarded the "Access to Learning Award" by the Bill & Melinda Gates Foundation, consisting of one million dollars to the EPM Foundation and the Library Network.[63]
+
+Additional libraries outside of this network include several other private, public, and university libraries.
+
+Medellín in 2013 won the Veronica Rudge Green Prize in Urban Design, awarded by Harvard University, due to PUI Integral Urban Project Northeast area, designed and implemented by Development Corporation Urbano. Medellín retains very little colonial architecture from the nineteenth century. Although the Aburrá Valley was a hotspot in agriculture and livestock throughout the colonial period, their relative wealth is not expressed in an outstanding and Cartagena, Tunja, Popayán and Bogotá civil and religious architecture. This can be explained by the fact that the population of Medellín was not political and administrative center and a place geographically isolated whose elite invested little in the development of monumental architecture. From the end of the colony remain, but with many transformations, the Candelaria Church and the Church of the Veracruz.
+
+The architecture produced in Colombia between 1850 and 1930 is called "Republican". The use of brick and implementation of European historical styles were the main novelty. Enrique Haeusler designed the Guayaquil Bridge in 1879. But it was the French architect Carlos Carré who headlined Republican nineteenth century architecture in Medellín. Carré came to town in 1889 and was hired to design and build the new Episcopal Cathedral and several commercial and residential buildings for different parts of the city, especially in the new neighborhood of Guayaquil. The Metropolitan Cathedral was completed in 1931; also are of authorship Vásquez and Carré buildings, which are located next to Plaza Cisneros. The Medellín Antioquia Railway Station was the work of Enrique Olarte, a work that allowed the definitive urban consolidation in Guayaquil sector. In the twenties Republican architecture reached its peak phase. In this period stand the old Municipal Palace (now the Museum of Antioquia) in 1928, the National Palace and the Palace of Departmental Government (now the Palace of Culture) between 1925 and 1928. The latter two works were designed by the Belgian architect Agustín Goovaerts, both inspired by the Belgian modernist, it applied the Romanesque and Gothic styles respectively. Other works of Goovaerts were the Church of the Sacred Heart (sector Guayaquil), the Church of San Ignacio, among others. The thirties highlighted such constructions of the Prado neighborhood as the Egyptian house and the current Teatro Prado.
+
+The main parks of the city include Berrío Park in the center of the city; Bolívar Park, a little further north and framed by the Metropolitan Cathedral; and others in more residential areas like Bethlehem Park, El Poblado Park, and Laureles Park. Several modern parks are interactive and have had a positive reception from the people because they are not only places of recreation but also of education. These include Barefoot Park, Wishes Park, Explora Park, and Bicentennial Park (which was recently opened to mark the bicentenary of Colombia).
+
+One of the most visited sites is the Arví Ecotourism Park, which has an area of about 20,000 hectares, covers virtually the entire territory of the village of Santa Elena, and runs between the towns of Bello, Copacabana, and Envigado. In its trails, lakes, forests and streams, one can practice various sports and activities like trekking, kayaking, biking, camping, fishing, swimming, sailing rowing, horseback riding, bike tours and picnics. Its promontory position over Medellín offers natural landscapes overlooking over the entire city.[citation needed]
+
+The city is surrounded from above by seven hills, which serve as natural viewpoints of the city and are sites for healthy leisure, recreation, enjoyment, research, sport, culture, education and ecotourism. The hills are El Volador, La Asomadera, Nutibara, Pan de Azúcar, El Salvador, El Picacho and Santo Domingo. In these natural public spaces one can find viewpoints, pre-Hispanic roads, religious icons, culture and Antioquian traditions, bird watching, the most complete herbal living of Aburrá Valley and the remains of early settlers native of Medellín, among other attractions.
+
+Other parks in the city include North Park and Juan Pablo II Park. The Santa Fe Zoo, founded in 1960, has about 1,000 animals from Asia, Africa, and the Americas.
+
+Wishes Park
+
+Botero Plaza
+
+Parque Lleras
+
+Bolívar Park
+
+Bicentennial Park
+
+Medellín is considered a top research city in medicine in Colombia, being an exponent of advanced surgical operations in the country and Latin America. Health clinics and dental centers in Medellín have become pioneers in offering high quality services in several medical areas. The University Hospital San Vicente de Paul, the Pablo Tobon Uribe Hospital, and Clinical Cardiovascular Santa Maria have received national and international recognition as pioneers in organ transplantation.[64]
+
+América Economía magazine ranked Medellín as having eight of the top 100 hospitals and clinics in Latin America. Its highest ranked hospital was Pablo Tobon Uribe Hospital, which ranked in seventh place in 2014.[65] The Pablo Tobon Uribe Hospital is non-profit and private.
+
+Specialized health centres such as San Vicente Foundation hospitals were recognized with the Silver Category of LEED certification. This is the only hospital outside of the United States of America to obtain this certification.[66]
+
+Among the most recognized universities with notable research work in medicine are the University of Antioquia, CES University,[67] and UPB University.
+
+Air pollution caused more than 7,000 deaths in 2016 in the city and represents a significant financial cost due to the treatment of respiratory diseases.[68]
+
+Medellín is also home to over 30 universities. Among the most important public universities are the following:
+
+There are also important technological centers such as the Metropolitan Institute of Technology (ITM), Jaime Isaza Cadavid's Politecnico, and Antioquia Institute of Technology.
+
+During the last decade, the administration of the city has emphasized public education, building schools and libraries in poor quarters. Private schools and colleges have a long tradition in the city, many run by the Catholic Church, private organizations, and foreign institutions. Among them are Gimnasio Internacional de Medellín, The Columbus School (the only SACS-approved school in the city), Theodoro Hertzl School, St. Ignatius Loyola College, Colegio Calasanz, Colegio Colombo Britanico, El Corazonista School, Marymount School, Montemayor Sagrado Corazon, Montessori School, Colegio Fontán, Gimnasio Los Pinares, Gimnasio Los Alcázares, San Jose de la Salle, Instituto Jorge Robledo, the Salesian Technical School Pedro Justo Berrío, Colegio Cumbres, Colegio San Marcos, Liceo Salazar y Herrera, and 'El Sufragio' Salesian School.
+
+Many non-governmental organizations and official organizations support the development of children and youth from poor communities. Ciudad Don Bosco cares for street children.[70] The pacification of the city brought organizations to the poorest quarters to work with youth involved in urban violence, in order to improve their opportunities. Medellín universities, public and private, also played a role, along with official institutions both local and national.
+
+Medellín has two airports, Olaya Herrera Airport (EOH), and José María Córdova Airport (MDE), which is located in the city of Rionegro, 29 kilometres (18 miles) east of the city of Medellín. In 2012 the busiest domestic flight route was between Jose Maria Cordova Airport and Bogotá while the busiest international route was between Jose Maria Cordova Airport and Panama City.
+
+The Jose Maria Cordova Airport receives international flights from important carriers such as American Airlines, Avianca, JetBlue and Lan Airlines, which makes the city accessible from the many regions of America. Avianca, the flag air-carrier of Colombia, has also an important activity at this airport. This airport has direct flights to important international destinations such as Lima, Quito, Mexico City, Madrid, Miami and New York City.
+
+Medellín has two transportation terminals, the North Transportation Terminal and the South Transportation Terminal. The city's public transport system includes diesel buses, taxis, tram and an urban train referred as the Medellín Metro, the only metro system in Colombia.
+
+The Metro connects the city with most of its metropolitan area. It has five lines. Line A goes from Niquía to La Estrella (north to south), while Line B goes from San Antonio to San Javier (downtown to west). In addition, Line K and Line J, an air cable car, locally known as Metrocable, serve a depressed and geographically difficult area. Line K begins at Acevedo Station on Metro Line A, and continues uphill, ending at Santo Domingo Savio. Line J begins at San Javier Station on Metro Line B, and continues uphill to La Aurora. Line L does not serve communal areas, rather, it is a tourist-oriented line which is connected to Arví Park and is part of a social project to bring retreats and nature to the masses.[71] Colombia has become Latin America's largest user of such complementary transportation service throughout the country.
+
+In 2006, construction began on Metroplús, a bus rapid transit service with a dedicated road, much like Bogotá's TransMilenio, to allow faster transit for the service's buses. The first line opened two years later than planned in 2011 and a second in 2013.[72] The first leg is the Troncal Medellín, which goes from the Universidad de Medellín in the west to Aranjuez in the northeast part of the city. Metroplus will help lessen the city's pollution and traffic, as many old buses will be taken out of service, while the new buses will work with natural gas.[73]
+
+Because of its projects on sustainable transport, the city obtained, along with San Francisco, the 2012 Sustainable Transport Award, given by the Institute for Transport and Development Policy.[74] According to EMBARQ Director Holger Dalkmann, "Medellín pioneered the use of cable cars as a transit alternative in low-income informal settlements in hilly areas, moving 3,000 passengers per hour per direction; a real breakthrough now being replicated in Caracas and Rio de Janeiro,"
+
+The Colombia and Latin America's second-largest and most modern tunnel, the Western Tunnel, officially named the Fernando Gomez Martinez Tunnel, is located between Medellín and Santa Fe de Antioquia. It is 4.6 km (3 mi) in length and offers security and service technologies for the users. It was inaugurated on January 20, 2006.[75][76]
+
+Originally, trams in Medellin were the most important transportation until 1950, but, after that, the rapidly increasing population and number of automobiles forcefully closed it in 1951. However, more than 60 years later, a new Translohr system (rubber-tired "tram"), the Ayacucho Tram, the first modern "tram" in Colombia, was opened on September 30, 2015. It is integrated with the metro system and the local bus network.
+
+The average amount of time people spend commuting with public transit in Medellín, for example to and from work, on a weekday is 66 min. 12% of public transit riders, ride for more than 2 hours every day. The average amount of time people wait at a stop or station for public transit is 11 min, while 14.% of riders wait for over 20 minutes on average every day. The average distance people usually ride in a single trip with public transit is 5.9 km, while 5% travel for over 12 km in a single direction.[77]
+
+The Aburrá Valley contains 58% of the population of the Department of Antioquia, and 67% of the Aburrá Valley population lives in the city of Medellín. Of the inhabitants of Medellín, 61.3% were born in the city, 38% in other parts of Colombia and 0.3% in another country.[79]
+
+According to the National Administrative Department of Statistics, Medellín had, by 2005, a population of 2,223,078 inhabitants, making it the second largest city in Colombia. The metropolitan area of Medellín in 2005 included 3,312,165 inhabitants. There are 5820 people per square kilometer in the city. There were 130,031 people living in the city townships; 46.7% of the population are male and 53.3% are female. Illiteracy is 9.8% in persons older than 5 years old. 98.8% of the households in Medellín have electricity, 97.3% have drinking water, and 91% have a land-line phone.[79]
+
+According to the 2005 DANE census, in that year Medellín registered 33,307 births,[80] slightly fewer than in 2004 (33,615). In 2005 the number of deaths was 10,828, in 2004 11,512.
+
+According to figures submitted by the DANE census 2005,[81] the ethnographic makeup of the city is:
+
+During the 17th and 18th centuries, Medellín received many immigrants from Spain[citation needed]. Most Indigenous peoples died from the introduction of European diseases, and many of those who survived intermarried with early Spanish settlers, who were mostly men; later, Spanish women also began to immigrate. During the 19th and 20th centuries, immigrants arrived from Lebanon, Jordan, Germany, Italy and Portugal. Many people from Medellín are referred to as Paisas, people of mainly Spanish ancestry, a lot of them Basque. There is a small Afro-Colombian and Zambo-Colombian (people of Indigenous and African descent) population.
+
+The Chocó Department is just west of Antioquia, and is home to many Afro-Colombian and Zambo-Colombian migrants to Medellín and its vicinity. Migration from the Colombian Caribbean coast has been important, especially that of young people who come to study in Medellín universities and remain to work in the city. The main foreign immigration is of Ecuadorians in informal trade.
+
+The culture in Medellín is strongly linked to a broader Paisa culture (see next section) whose unique attributes include their Spanish accent, cuisine, and hospitality. Today, Medellín has several cultural attractions for the public including approximately 40 museums, 21 public parks, 28 theaters, and several public libraries.[82] The city also contains several National Monuments of Colombia.
+
+Most people in Medellín are Catholic, as reflected by Medellín's several churches and religious activities. Among the most representative churches are the Metropolitan Cathedral, the largest cathedral in the world built entirely in baked brick. There is also the Basilica of Our Lady of Candelaria, which was the official cathedral until 1931, the Church of San Ignacio, Baroque on the outside and Colonial on inside, the Church of San José, the Church of San Antonio, which has one of the biggest domes in Colombia, the Church of San José del Poblado, located in the Parque del Poblado where the first European settlement in the Aburrá Valley was founded in 1616, and the Church of Nuestra Señora de Belén. All of these temples have religious art and are located in the center of the city, which facilitates their journeys.
+
+In December, the city is covered with thousands of fairy lights, creating the famous Alumbrados (Christmas lights), which are considered by the National Geographic as one of the ten most beautiful in the world,[83] and which can be seen mainly on La Playa Avenue and the Medellín River.
+
+Plaza Mayor is the epicenter of large events and business. By a decree of the municipal government, between 1980 and 1990 all developments or tall buildings necessarily included a sculpture of a famous artist. That is one reason why Medellín has the largest number of sculptures per square kilometer in Colombia.[citation needed]
+
+Furthermore, the city has several festivals and exhibitions year-round. The silletero tradition is also closely tied to the region and is considered a part of Colombian cultural heritage. Since 1957, this tradition has continued in the Silleta Parade that takes place during the annual Festival of the Flowers, where silletas designed with flower arrangements are carried.
+
+Works of many prominent artists, both local and foreign, can be seen on the streets of the city. Some artists who stand out are the masters Rodrigo Arenas Betancur and Fernando Botero.
+
+The inhabitants of Medellín are often called Antioqueños (people of Antioquia) after their province, rather than Medellínenses (people of Medellín) after their city. They are also often known as Paisas, a name which some suggest comes from the coffee growers. The term Paisa comes from the word paisano, meaning "fellow countryman". Paisas make up one of the five different regional cultures within Colombia. In addition to Antioquia, the Paisa region includes the departments of Caldas, Risaralda, Quindio and some towns of Valle del Cauca and Tolima. Although Paisa culture is dominant in Medellín, the so-called "Paisa Capital", the city is becoming more cosmopolitan, now offering music from other regions of Colombia (Vallenato and Chocó), and a variety of restaurants including Chinese, Cuban, and Argentinian.
+
+The Paisa culture has a Spanish background, and is traditionally Catholic, and entrepreneurial.[citation needed] Paisas are said to speak softly and quickly, to smile easily, and to love music, poetry, soccer, bargaining in the markets, and parties. They are proud of their city, and work hard to keep it clean, stemming from the campaign begun in the 1980s, "Depende tambien de ti, darle amor a Medellín" (It depends on you too to give love to Medellín). The Medellín weekend nightlife, in discos, pubs, parks, and certain dedicated streets, is traditionally called rumba.[84]
+
+Medellín has about 40 galleries, which are one of the main attractions of the city. Some of the main museums include the following:
+
+Other prominent museums are Centro Cultural Banco de la República, Entomological Museum Francisco Luis Gallego, Casa Museo Santa Fe, Museum of Natural Sciences, Ethnographic Museum Miguel Ángel Builes and the Mother Laura Ethnographic Museum.[88]
+
+Medellin is well known for having great public art, and there are many buildings that have prominent sculptures outside them. In addition to the sculpture park of Fernando Botero, there are many other sculptural gems by a variety of contemporary and modernist artists scattered around the city. They include works by the artist Hugo Zapata amongst others.
+
+The cuisine of Medellín is again tied to the larger culture of Antioquia. A typical regional dish is the bandeja paisa, meaning the "paisa platter", which usually includes beans, rice, pork cracklings (or "chicharrón"), chorizo, a fried egg, patacónes, salad and avocado. It is traditionally served on a tray slab or wood. It is traditional to consume meals with arepas, which are made with cooked, milled, and mixed corn without further ingredients.
+
+For breakfast, it is common to accompany the food with hot chocolate and possibly a slice of cheese to dunk in the drink. Parva is a traditional component of the Antioquian gastronomy as well. This name is given to a wide variety of sweet and savory baked goods, including pan de queso, pan de bono, buñuelos, and pastries.
+
+Other foods that are typical in the region stem from Colombian food industries, such as Postobón Colombian sodas, the regional aguardiente known as Aguardiente Antioqueño, and Jet chocolate bars.
+
+Soccer is the most popular sport and is widely played in the city. Medellín has two professional clubs: Independiente Medellín, founded in 1913, and Atlético Nacional, founded in 1935. Both teams play at the Atanasio Girardot Stadium. The city has a soccer legacy thanks to notable players such as Rene Higuita, Iván Córdoba, Andrés Escobar, and Víctor Aristizábal, among many others. Other notable sportsmen of the city are the professional golfer and PGA Tour player Camilo Villegas, Medillin-born Israeli Olympic show jumping rider Daniel Bluman, and the retired Formula One, Champ Car, and IndyCar driver Roberto Guerrero.
+
+A popular sport in Medellín, and generally throughout Antioquia, is horseback riding; therefore, it has encouraged trade and production of tools and equipments for this activity, such as chairs and horseshoes for export. During the Festival of the Flowers, the cavalcades achieved a Guinness World Record in 1996 and 1999.
+
+The city also has two Colombian professional basketball teams: the Arrieros of Antioquia and the Mountain Academy.
+
+The Atanasio Girardot Sports Complex is the main sports arena complex of the city. It covers an area of 280,000 m2 (3,013,895 sq ft) and encompasses fields and stadiums for practice and competition for 34 sports. This is the headquarters of most professional sports leagues in Medellín. The sports complex has hosted several events, including the 2011 FIFA U-20 World Cup, the 2010 South American Games, and the 2001 Copa América.
+
+In 2011, Medellín hosted the 15th IAAF Pan American Race Walking Cup.  Athletes and teams from the countries in North, South, and Central American as well as the Caribbean Islands participated. In 2013, Medellín hosted the IAAF Pan American Junior Athletics Championships for track and field. Again, athletes and teams from the countries in North, South, and Central America as well as the Caribbean Islands participated. The junior athletes competed as a test trial for the 2018 Summer Youth Olympics.
+
+Medellín bid to host the 2018 Summer Youth Olympics but was defeated by Buenos Aires in the July 4, 2013 vote.[89]
+
+Another representative sport in the city is cycling. Its respective sport venue is the Martin Rodriguez Velodrome, named after Colombian road racing cyclist Martín Emilio Rodríguez. BMX is also catered for, and its main venue is the BMX Track Antonio Roldán Betancur. The retired cycling three-time Tour de France stage winner and World Time-Trial Champion Santiago Botero Echeverry and the Olympic Gold Medalist and multiple BMX World Champion Mariana Pajón Londoño are both from Medellín.
+
+EnCicla is the name of Medellín's bicycle sharing system, the first bike sharing program in Latin America and the only one of its kind in Colombia. It was the shared winner of the Sustainable Transport Award in 2012 along with San Francisco. EnCicla is the result of an agreement between the metropolitan area of the Valley of Aburrá and EAFIT University. EnCicla is integrated within the city's existing infrastructure of cycle routes, mass transit, and public transport systems. It is available from Monday to Friday from 5:30 am to 8 pm from every EnCicla station.
+
+The coat of arms, flag and anthem of the city, has the recognition of official symbols of the municipality of Medellín according to Decree No. 151 of February 20, 2002, and as emblems of the city are part of the corporate image of management municipal, and therefore are present in the acts, events and official media in which these should appear by its representative character.
+
+The Medellín coat of arms is the oldest emblem of the city, having its origins in a grant by King Charles II of Spain by royal decree issued in Madrid on March 31 of 1678:
+
+...On a blue field shield, a very thick and round tower, battlemented, an inescutcheon of fifteen parts – seven blue and eight gold, on each of the sides a smaller tower, and in between them an image of Our Lady on a cloud with her son in her arms...
+
+However, a more refined and structured in heraldic language, though not official, would be:
+
+In an Azure field, a round tower of gold stands, masoned and clarified by sable, with a checkered escutcheon of 15 pieces – 7 blue and 8 gold (coat of arms of House of Portocarrero) – stamped with an ancient crown of gold between its two towers, with a cloud upon which stands the image of Our Lady of Candelaria carrying the Child in her left arm, a candle in her right hand, radiant, she is flanked by forming clouds from each county.
+
+The blazon has remained over time since it was granted, without further changes to the aesthetics, it is noteworthy that there are different stylistic versions between the Mayor and City Council also meets aesthetic not heraldic standards.
+
+To strengthen the links with the region, the municipality adopted the flag of the Department of Antioquia, which was added to the coat of arms of the city, so that these could make difference. The flag consists of two horizontal stripes of equal proportions, the white top and green bottom, and in the middle between two strips is located the coat. The white color symbolizes purity, integrity, obedience, firmness and eloquence. The green represents hope, abundance, freedom and faith.
+
+The anthem of the city of Medellín is "Anthem of Antioquia", according to Decree No. 151 of February 20, 2002, Article 10, which says: "Anthem of Medellín. To unify the ideals of the region the Antioquia anthem is adopted (lyrics by Epifanio Mejia and music by Gonzalo Vidal) as the Anthem of the Municipality of Medellín. It will be sung in all official functions where the Mayor of Medellín is present."
+
+Medellín is twinned with:
+
+Basilica of Our Lady of Candelaria
+
+San Ignacio Square
+
+La Alpujarra Administrative Center
+
+Downtown Medellín
+
+Pilot Public Library
+
+Christmas lights at Nutibara Hill
+
+Botanical Garden of Medellín
+
+Paraninfo University of Antioquia
+
+Antique Railway Station
+
+Palace of the Fine Arts
+
+International Center of Business CIC
+
+Metropolitan Cathedral
+
+Metropolitan Theatre
+
+Wishes Park
+
+Barefoot Park
+
+Estadio station
+
+Parque Explora
+
+Pueblito Paisa
+
+EAFIT University
+
+Headquarters of Hewlett-Packard in Route N

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+
+Cardinal Armand Jean du Plessis, Duke of Richelieu (French pronunciation: ​[aʁmɑ̃ ʒɑ̃ dy plɛsi]; 9 September 1585 – 4 December 1642), commonly referred to as Cardinal Richelieu (UK: /ˈrɪʃəljɜː, ˈriːʃ-/,[1][2][3] US: /ˈrɪʃəl(j)uː, ˈriːʃ-/;[3][4][5] French: Cardinal de Richelieu [kaʁdinal d(ə) ʁiʃ(ə)ljø] (listen)), was a French clergyman and statesman. He was consecrated as a bishop in 1607 and was appointed Foreign Secretary in 1616. Richelieu soon rose in both the Catholic Church and the French government, becoming a cardinal in 1622, and King Louis XIII's chief minister in 1624. He remained in office until his death in 1642; he was succeeded by Cardinal Mazarin, whose career he had fostered.
+
+Cardinal de Richelieu was often known by the title of the king's "Chief Minister" or "First Minister". He sought to consolidate royal power and crush domestic factions. By restraining the power of the nobility, he transformed France into a strong, centralized state. His chief foreign policy objective was to check the power of the Austro-Spanish Habsburg dynasty and to ensure French dominance in the Thirty Years' War that engulfed Europe. Although he was a cardinal, he did not hesitate to make alliances with Protestant rulers in an attempt to achieve his goals. While a powerful political figure, events like the Day of the Dupes (Jour des Dupes) show that in fact he very much depended on the king's confidence to keep this power.
+
+As alumnus of the University of Paris and headmaster of the College of Sorbonne, he renovated and extended the institution. Richelieu was also famous for his patronage of the arts; most notably, he founded the Académie française, the learned society responsible for matters pertaining to the French language. Richelieu is also known by the sobriquet l'Éminence rouge ("the Red Eminence"), from the red shade of a cardinal's clerical dress and the style "eminence" as a cardinal. As an advocate for Samuel de Champlain and of the retention of New France, he founded the Compagnie des Cent-Associés and saw the Treaty of Saint-Germain-en-Laye return Quebec City to French rule under Champlain, after the settlement had been taken by the Kirkes in 1629. The city would prove to be at the heart of Francophone culture in North America.
+
+Richelieu has been depicted in popular fiction frequently, most notably as the lead villain in Alexandre Dumas's 1844 novel The Three Musketeers and its numerous film adaptations.
+
+Born in Paris, Armand du Plessis was the fourth of five children and the last of three sons: he was delicate from childhood, and suffered frequent bouts of ill-health throughout his life. His family was somewhat prominent, belonging to the lesser nobility of Poitou:[6] his father, François du Plessis, seigneur de Richelieu, was a soldier and courtier who served as the Grand Provost of France,[7] and his mother, Susanne de La Porte, was the daughter of a famous jurist.[8] When he was five years old, his father died fighting in the French Wars of Religion,[9] leaving the family in debt; with the aid of royal grants, however, the family was able to avoid financial difficulties. At the age of nine, young Richelieu was sent to the College of Navarre in Paris to study philosophy.[10] Thereafter, he began to train for a military career.[11] His private life seems to have been typical of a young officer of the era: in 1605, aged twenty, he was treated by Théodore de Mayerne for pneumonia.[12]
+
+Henry III had rewarded Richelieu's father for his participation in the Wars of Religion by granting his family the bishopric of Luçon.[13] The family appropriated most of the revenues of the bishopric for private use; they were, however, challenged by clergymen who desired the funds for ecclesiastical purposes. To protect the important source of revenue, Richelieu's mother proposed to make her second son, Alphonse, the bishop of Luçon.[14] Alphonse, who had no desire to become a bishop, became instead a Carthusian monk.[15] Thus, it became necessary that the younger Richelieu join the clergy. He had strong academic interests and threw himself into studying for his new post.[citation needed]
+
+In 1606 Henry IV nominated Richelieu to become Bishop of Luçon.[14] As Richelieu had not yet reached the canonical minimum age, it was necessary that he journey to Rome for a special dispensation from Pope Paul V. This secured, Richelieu was consecrated bishop in April 1607. Soon after he returned to his diocese in 1608, Richelieu was heralded as a reformer.[16] He became the first bishop in France to implement the institutional reforms prescribed by the Council of Trent between 1545 and 1563.[17]
+
+At about this time, Richelieu became a friend of François Leclerc du Tremblay (better known as "Père Joseph" or "Father Joseph"), a Capuchin friar, who would later become a close confidant. Because of his closeness to Richelieu, and the grey colour of his robes, Father Joseph was also nicknamed L'éminence grise ("the Grey Eminence"). Later, Richelieu often used him as an agent during diplomatic negotiations.[18]
+
+In 1614, the clergymen of Poitou asked Richelieu to be one of their representatives to the Estates-General.[19] There, he was a vigorous advocate of the Church, arguing that it should be exempt from taxes and that bishops should have more political power. He was the most prominent clergyman to support the adoption of the decrees of the Council of Trent throughout France;[20] the Third Estate (commoners) was his chief opponent in this endeavour. At the end of the assembly, the First Estate (the clergy) chose him to deliver the address enumerating its petitions and decisions.[21] Soon after the dissolution of the Estates-General, Richelieu entered the service of King Louis XIII's wife, Anne of Austria, as her almoner.[22]
+
+Richelieu advanced politically by faithfully serving the Queen-Mother's favourite, Concino Concini, the most powerful minister in the kingdom.[23] In 1616, Richelieu was made Secretary of State, and was given responsibility for foreign affairs.[21] Like Concini, the Bishop was one of the closest advisors of Louis XIII's mother, Marie de Médicis. The Queen had become Regent of France when the nine-year-old Louis ascended the throne; although her son reached the legal age of majority in 1614, she remained the effective ruler of the realm.[24] However, her policies, and those of Concini, proved unpopular with many in France. As a result, both Marie and Concini became the targets of intrigues at court; their most powerful enemy was Charles de Luynes.[25] In April 1617, in a plot arranged by Luynes, Louis XIII ordered that Concini be arrested, and killed should he resist; Concini was consequently assassinated, and Marie de Médicis overthrown.[26] His patron having died, Richelieu also lost power; he was dismissed as Secretary of State, and was removed from the court.[26] In 1618, the King, still suspicious of the Bishop of Luçon, banished him to Avignon. There, Richelieu spent most of his time writing; he composed a catechism entitled L'Instruction du chrétien.[27]
+
+In 1619, Marie de Médicis escaped from her confinement in the Château de Blois, becoming the titular leader of an aristocratic rebellion. The King and the duc de Luynes recalled Richelieu, believing that he would be able to reason with the Queen. Richelieu was successful in this endeavour, mediating between her and her son.[28] Complex negotiations bore fruit when the Treaty of Angoulême was ratified; Marie de Médicis was given complete freedom, but would remain at peace with the King. The Queen-Mother was also restored to the royal council.[citation needed]
+
+After the death of the King's favourite, the duc de Luynes, in 1621, Richelieu rose to power quickly. The year after, the King nominated Richelieu for a cardinalate, which Pope Gregory XV accordingly granted in September 1622.[29] Crises in France, including a rebellion of the Huguenots, rendered Richelieu a nearly indispensable advisor to the King. After he was appointed to the royal council of ministers on 29 April 1624,[30] he intrigued against the chief minister, Charles, duc de La Vieuville.[28] On 12 August of the same year, La Vieuville was arrested on charges of corruption, and Cardinal Richelieu took his place as the King's principal minister the following day, although the Cardinal de la Rochefoucauld nominally remained president of the council (Richelieu was officially appointed president in November 1629).[31]
+
+Cardinal Richelieu's policy involved two primary goals: centralization of power in France[32] and opposition to the Habsburg dynasty (which ruled in both Austria and Spain).[33] Shortly after he became Louis' principal minister, he was faced with a crisis in Valtellina, a valley in Lombardy (northern Italy). To counter Spanish designs on the territory, Richelieu supported the Protestant Swiss canton of Grisons, which also claimed the strategically important valley. The Cardinal deployed troops to Valtellina, from which the Pope's garrisons were driven out.[34] Richelieu's early decision to support a Protestant canton against the Pope was a foretaste of the purely diplomatic power politics he would espouse in his foreign policy.
+
+To further consolidate power in France, Richelieu sought to suppress the influence of the feudal nobility. In 1626, he abolished the position of Constable of France and ordered all fortified castles razed, excepting only those needed to defend against invaders.[35] Thus he stripped the princes, dukes, and lesser aristocrats of important defences that could have been used against the King's armies during rebellions. As a result, Richelieu was hated by most of the nobility.
+
+Another obstacle to the centralization of power was religious division in France. The Huguenots, one of the largest political and religious factions in the country, controlled a significant military force, and were in rebellion.[36] Moreover, the King of England, Charles I, declared war on France in an attempt to aid the Huguenot faction. In 1627, Richelieu ordered the army to besiege the Huguenot stronghold of La Rochelle; the Cardinal personally commanded the besieging troops.[37] English troops under the Duke of Buckingham led an expedition to help the citizens of La Rochelle, but failed abysmally. The city, however, remained firm for over a year before capitulating in 1628.
+
+Although the Huguenots suffered a major defeat at La Rochelle, they continued to fight, led by Henri, duc de Rohan. Protestant forces, however, were defeated in 1629; Rohan submitted to the terms of the Peace of Alais.[38] As a result, religious toleration for Protestants, which had first been granted by the Edict of Nantes in 1598, was permitted to continue, but the Cardinal abolished their political rights and protections.[38] Rohan was not executed (as were leaders of rebellions later in Richelieu's tenure); in fact, he later became a commanding officer in the French army.
+
+Habsburg Spain exploited the French conflict with the Huguenots to extend its influence in northern Italy. It funded the Huguenot rebels to keep the French army occupied, meanwhile expanding its Italian dominions. Richelieu, however, responded aggressively; after La Rochelle capitulated, he personally led the French army to northern Italy to restrain Spain. On 26 November 1629, he was created duc de Richelieu and a Peer of France.
+In the next year, Richelieu's position was seriously threatened by his former patron, Marie de Médicis. Marie believed that the Cardinal had robbed her of her political influence; thus, she demanded that her son dismiss the chief minister.[39] Louis XIII was not, at first, averse to such a course of action, as he personally disliked Richelieu.[21] Despite this, the persuasive statesman was able to secure the king as an ally against his own mother. On 11 November 1630, Marie de Médicis and the King's brother, Gaston, duc d'Orléans, secured the King's agreement for the dismissal. Richelieu, however, was aware of the plan, and quickly convinced the King to repent.[40] This day, known as the Day of the Dupes, was the only one on which Louis XIII took a step toward dismissing his minister. Thereafter, the King was unwavering in his political support for him.
+
+Meanwhile, Marie de Médicis was exiled to Compiègne. Both Marie and the duc d'Orléans continued to conspire against Richelieu, but their schemes came to nothing. The nobility also remained powerless. The only important rising was that of Henri, duc de Montmorency in 1632; Richelieu, ruthless in suppressing opposition, ordered the duke's execution. In 1634, the Cardinal had one of his outspoken critics, Urbain Grandier, burned at the stake in the Loudun affair. These and other harsh measures were orchestrated by Richelieu to intimidate his enemies. He also ensured his political security by establishing a large network of spies in France as well as in other European countries.
+
+Henri Motte's depiction of Cardinal Richelieu at the Siege of La Rochelle.
+
+Letter of Cardinal Richelieu to Claude de Razilly asking him to do everything in his power to relieve Ré Island in the Siege of Saint-Martin-de-Ré, July 1627.
+
+On the "Day of the Dupes" in 1630, it appeared that Marie de Médicis had secured Richelieu's dismissal. Richelieu, however, survived the scheme, and Marie was exiled as a result.
+
+Before Richelieu's ascent to power, most of Europe had become enmeshed in the Thirty Years' War (1618–1648). France was not openly at war with the Habsburgs, who ruled Spain and the Holy Roman Empire, so subsidies and aid were provided secretly to their adversaries.[41] He considered the Dutch Republic as one of France's most important allies, for it bordered directly with the Spanish Netherlands and was right in the middle of the Eighty Years' War with Spain at that time. Luckily for him, Richelieu was a bon français, just like the king, who had already decided to subsidize the Dutch to fight against the Spanish via the Treaty of Compiègne in June 1624, prior to Richelieu's appointment to First Minister in August.[42] That same year, a military expedition, secretly financed by France and commanded by Marquis de Coeuvres, started an action with the intention of liberating the Valtelline from Spanish occupation. In 1625, Richelieu also sent money to Ernst von Mansfeld, a famous mercenary general operating in Germany in English service. However, in May 1626, when war costs had almost ruined France, king and cardinal made peace with Spain via the Treaty of Monçon.[43] This peace quickly broke down after tensions due to the War of the Mantuan Succession.[44]
+
+In 1629, Emperor Ferdinand II subjugated many of his Protestant opponents in Germany. Richelieu, alarmed by Ferdinand's growing influence, incited Sweden to intervene, providing money.[45] In the meantime, France and Spain remained hostile due to Spain's ambitions in northern Italy. At that time northern Italy was a major strategic region in Europe's balance of power, serving as a link between the Habsburgs in the Empire and in Spain. Had the imperial armies dominated this region, France would have been threatened by Habsburg encirclement. Spain was meanwhile seeking papal approval for a universal monarchy. When in 1630 French diplomats in Regensburg agreed to make peace with Spain, Richelieu refused to support them. The agreement would have prohibited French interference in Germany. Therefore, Richelieu advised Louis XIII to refuse to ratify the treaty. In 1631, he allied France to Sweden, who had just invaded the empire, in the Treaty of Bärwalde.[45]
+
+Military expenses placed a considerable strain on royal revenues. In response, Richelieu raised the gabelle (salt tax) and the taille (land tax).[46] The taille was enforced to provide funds to raise armies and wage war. The clergy, nobility, and high bourgeoisie were either exempt or could easily avoid payment, so the burden fell on the poorest segment of the nation. To collect taxes more efficiently, and to keep corruption to a minimum, Richelieu bypassed local tax officials, replacing them with intendants (officials in the direct service of the Crown).[47] Richelieu's financial scheme, however, caused unrest among the peasants; there were several uprisings in 1636 to 1639.[48] Richelieu crushed the revolts violently, and dealt with the rebels harshly.[49]
+
+Because he openly aligned France with Protestant powers, Richelieu was denounced by many as a traitor to the Roman Catholic Church. Military action, at first, was disastrous for the French, with many victories going to Spain and the Empire.[50] Neither side, however, could obtain a decisive advantage, and the conflict lingered on after Richelieu's death. Richelieu was instrumental in redirecting the Thirty Years' War from the conflict of Protestantism versus Catholicism to that of nationalism versus Habsburg hegemony.[51] In this conflict France effectively drained the already overstretched resources of the Habsburg empire and drove it inexorably towards bankruptcy.[52] The defeat of Habsburg forces at the Battle of Lens in 1648, coupled with their failure to prevent a French invasion of Catalonia, effectively spelled the end for Habsburg domination of the continent, and for the personal career of Spanish prime minister Olivares.[52] Indeed, in the subsequent years it would be France, under the leadership of Louis XIV, who would attempt to fill the vacuum left by the Habsburgs in the Spanish Netherlands and supplant Spain as the dominant European power.[citation needed]
+
+When Richelieu came to power, New France, where the French had a foothold since Jacques Cartier, had no more than 100 permanent European inhabitants.[53] Richelieu encouraged Louis XIII to colonize the Americas by the foundation of the Compagnie de la Nouvelle France in imitation of the Dutch West India Company. Unlike the other colonial powers, France encouraged a peaceful coexistence in New France between Natives and Colonists and sought the integration of Indians into colonial society.[54][55] Samuel de Champlain, governor of New France at the time of Richelieu, saw intermarriage between French and Indians as a solution to increase population in its colony.[56] Under the guidance of Richelieu, Louis XIII issued the Ordonnance of 1627 by which the Indians, converted to Catholicism, were considered as "natural Frenchmen":
+
+The descendants of the French who are accustomed to this country [New France], together with all the Indians who will be brought to the knowledge of the faith and will profess it, shall be deemed and renowned natural Frenchmen, and as such may come to live in France when they want, and acquire, donate, and succeed and accept donations and legacies, just as true French subjects, without being required to take letters of declaration of naturalization.[57]
+
+The 1666 census of New France, conducted some 20 years after the death of Cardinal Richelieu, showed a population of 3,215 habitants in New France, many more than there had been only a few decades earlier, but also a great difference in the number of men (2,034) and women (1,181).[58]
+
+Towards the end of his life, Richelieu alienated many people, including Pope Urban VIII. Richelieu was displeased by the Pope's refusal to name him the papal legate in France;[59] in turn, the Pope did not approve of the administration of the French church, or of French foreign policy. However, the conflict was largely healed when the Pope granted a cardinalate to Jules Mazarin, one of Richelieu's foremost political allies, in 1641. Despite troubled relations with the Roman Catholic Church, Richelieu did not support the complete repudiation of papal authority in France, as was advocated by the Gallicanists.[60]
+
+As he neared death, Richelieu faced a plot that threatened to remove him from power. The cardinal had introduced a young man named Henri Coiffier de Ruzé, marquis de Cinq-Mars to Louis XIII's court.[61] The Cardinal had been a friend of Cinq-Mars' father.[61] More importantly, Richelieu hoped that Cinq-Mars would become Louis' favourite, so that he could indirectly exercise greater influence over the monarch's decisions. Cinq-Mars had become the royal favourite by 1639, but, contrary to Cardinal Richelieu's belief, he was not easy to control. The young marquis realized that Richelieu would not permit him to gain political power.[62] In 1641, he participated in the comte de Soissons' failed conspiracy against Richelieu, but was not discovered.[63] Then, the following year, he schemed with leading nobles (including the King's brother, the duc d'Orléans) to raise a rebellion; he also signed a secret agreement with the King of Spain, who promised to aid the rebels.[64] Richelieu's spy service, however, discovered the plot, and the Cardinal received a copy of the treaty.[65] Cinq-Mars was promptly arrested and executed; although Louis approved the use of capital punishment, he grew more distant from Richelieu as a result.[citation needed]
+
+However, Richelieu was now dying. For many years he had suffered from recurrent fevers (possibly malaria), strangury, intestinal tuberculosis with fistula, and migraine. Now his right arm was suppurating with tubercular osteitis, and he coughed blood (after his death, his lungs were found to have extensive cavities and caseous necrosis). His doctors continued to bleed him frequently, further weakening him.[66] As he felt his death approaching, he named Mazarin, one of his most faithful followers, to succeed him as chief minister to the King.[67]
+
+Richelieu died on 4 December 1642, aged 57. His body was embalmed and interred at the church of the Sorbonne. During the French Revolution, the corpse was removed from its tomb, and the mummified front of his head, having been removed and replaced during the original embalming process, was stolen. It ended up in the possession of Nicholas Armez of Brittany by 1796, and he occasionally exhibited the well-preserved face. His nephew, Louis-Philippe Armez, inherited it and also occasionally exhibited it and lent it out for study. In 1866, Napoleon III persuaded Armez to return the face to the government for re-interment with the rest of Richelieu's body. An investigation of subsidence of the church floor enabled the head to be photographed in 1895.[68][69]
+
+Richelieu was a famous patron of the arts. An author of various religious and political works (most notably his Political Testament), he sent his agents abroad[70] in search of books and manuscripts for his unrivaled library, which he specified in his will – leaving it to his great-nephew fully funded – should serve not merely his family but to be open at fixed hours to scholars. The manuscripts alone numbered some 900, bound as codices in red Morocco with the cardinal's arms. The library was transferred to the Sorbonne in 1660.[71] He funded the literary careers of many writers. He was a lover of the theatre, which was not considered a respectable art form during that era; a private theatre was a feature of the Palais-Cardinal. Among the individuals he patronized was the famous playwright Pierre Corneille.[72] Richelieu was also the founder and patron of the Académie française, the pre-eminent French literary society.[73] The institution had previously been in informal existence; in 1635, however, Cardinal Richelieu obtained official letters patent for the body. The Académie française includes forty members, promotes French literature, and remains the official authority on the French language. Richelieu served as the Académie's protector. Since 1672, that role has been fulfilled by the French head of state.[citation needed]
+
+In 1622, Richelieu was elected the proviseur or principal of the Sorbonne.[74] He presided over the renovation of the college's buildings and over the construction of its famous chapel, where he is now entombed. As he was Bishop of Luçon, his statue stands outside the Luçon cathedral.[citation needed]
+
+Richelieu oversaw the construction of his own palace in Paris, the Palais-Cardinal.[75] The palace, renamed the Palais Royal after Richelieu's death, now houses the French Constitutional Council, the Ministry of Culture, and the Conseil d'État. The Galerie de l'avant-cour had ceiling paintings by the Cardinal's chief portraitist, Philippe de Champaigne, celebrating the major events of the Cardinal's career; the Galerie des hommes illustres had twenty-six historicizing portraits of great men, larger than life, from Abbot Suger to Louis XIII; some were by Simon Vouet, others were careful copies by Philippe de Champaigne from known portraits;[76] with them were busts of Roman emperors. Another series of portraits of authors complemented the library.  The architect of the Palais-Cardinal, Jacques Lemercier, also received a commission to build a château and a surrounding town in Indre-et-Loire; the project culminated in the construction of the Château Richelieu and the town of Richelieu. To the château, he added one of the largest art collections in Europe and the largest collection of ancient Roman sculpture in France. The heavily resurfaced and restored Richelieu Bacchus continued to be admired by neoclassical artists.[77] Among his 300 paintings by moderns, most notably, he owned Leonardo's Virgin and Child with Saint Anne, The Family of the Virgin by Andrea del Sarto, the two famous Bacchanales of Nicolas Poussin, as well as paintings by Veronese and Titian, and Diana at the Bath by Rubens, for which he was so glad to pay the artist's heirs 3,000 écus, that he made a gift to Rubens' widow of a diamond-encrusted watch. His marble portrait bust by Bernini was not considered a good likeness and was banished to a passageway.[78]
+
+The fittings of his chapel in the Palais-Cardinal, for which Simon Vouet executed the paintings, were of solid gold – crucifix, chalice, paten, ciborium, candlesticks – set with 180 rubies and 9,000 diamonds.[79] His taste also ran to massive silver, small bronzes and works of vertu, enamels and rock crystal mounted in gold, Chinese porcelains, tapestries and Persian carpets, cabinets from Italy, and Antwerp and the heart-shaped diamond bought from Alphonse Lopez that he willed to the king.  When the Palais-Cardinal was complete, he donated it to the Crown, in 1636. With the Queen in residence, the paintings of the Grand Cabinet were transferred to Fontainebleau and replaced by copies, and the interiors were subjected to much rearrangement.[citation needed]
+
+Michelangelo's two Slaves were among the rich appointments of the château Richelieu, where there were the Nativity triptych by Dürer, and paintings by Mantegna, Lorenzo Costa and Perugino, lifted from the Gonzaga collection at Mantua by French military forces in 1630, as well as numerous antiquities.[citation needed]
+
+Richelieu's tenure was a crucial period of reform for France. Earlier, the nation's political structure was largely feudal, with powerful nobles and a wide variety of laws in different regions.[81] Parts of the nobility periodically conspired against the King, raised private armies, and allied themselves with foreign powers. This system gave way to centralized power under Richelieu.[82] Local and even religious interests were subordinated to those of the whole nation, and of the embodiment of the nation – the King. Equally critical for France was Richelieu's foreign policy, which helped restrain Habsburg influence in Europe. Richelieu did not survive to the end of the Thirty Years' War. However, the conflict ended in 1648, with France emerging in a far better position than any other power, and the Holy Roman Empire entering a period of decline.[citation needed]
+
+Richelieu's successes were extremely important to Louis XIII's successor, King Louis XIV. He continued Richelieu's work of creating an absolute monarchy; in the same vein as the Cardinal, he enacted policies that further suppressed the once-mighty aristocracy, and utterly destroyed all remnants of Huguenot political power with the Edict of Fontainebleau. Moreover, Louis took advantage of his nation's success during the Thirty Years' War to establish French hegemony in continental Europe. Thus, Richelieu's policies were the requisite prelude to Louis XIV becoming the most powerful monarch, and France the most powerful nation, in all of Europe during the late seventeenth century.[citation needed]
+
+Richelieu is also notable for the authoritarian measures he employed to maintain power. He censored the press,[83] established a large network of internal spies, forbade the discussion of political matters in public assemblies such as the Parlement de Paris (a court of justice), and had those who dared to conspire against him prosecuted and executed. The Canadian historian and philosopher John Ralston Saul has referred to Richelieu as the "father of the modern nation-state, modern centralised power [and] the modern secret service."[citation needed]
+
+Richelieu's motives are the focus of much debate among historians: some see him as a patriotic supporter of the monarchy, while others view him as a power-hungry cynic. The latter image gained further currency due to Alexandre Dumas' The Three Musketeers, which depicts Richelieu as a self-serving and ruthless de facto ruler of France.[citation needed]
+
+Despite such arguments, Richelieu remains an honoured personality in France. He has given his name to a battleship and a battleship class.
+
+His legacy is also important for the world at large; his ideas of a strong nation-state and aggressive foreign policy helped create the modern system of international politics. The notions of national sovereignty and international law can be traced, at least in part, to Richelieu's policies and theories, especially as enunciated in the Treaty of Westphalia that ended the Thirty Years' War.[citation needed]
+
+A less renowned aspect of his legacy is his involvement with Samuel de Champlain and the fledgling colony along the St. Lawrence River. The retention and promotion of Canada under Richelieu allowed it – and through the settlement's strategic location, the St. Lawrence-Great Lakes gateway into the North American interior – to develop into a French empire in North America, parts of which eventually became modern Canada and Louisiana.[citation needed]
+
+As of April 2013, the Internet Movie Database listed 94 films and television programs in which Cardinal Richelieu is a character. Richelieu is one of the clergymen most frequently portrayed in film, notably in the many versions of Alexandre Dumas's The Three Musketeers. He is usually portrayed as a sinister character, but the 1950 Cyrano de Bergerac shows Richelieu (played by Edgar Barrier in a scene not from Rostand's original verse drama) as compassionate to Cyrano's financial plight, and playfully having enjoyed the duel at the theatre. Actors who have portrayed Cardinal Richelieu on film and television include Nigel De Brulier, George Arliss, Miles Mander, Vincent Price, Charlton Heston, Tcheky Karyo, Stephen Rea, Tim Curry, Christoph Waltz and Peter Capaldi.
+
+The 1839 play Richelieu; Or the Conspiracy, by Edward Bulwer-Lytton, portrayed Richelieu uttering the now famous line, "The pen is mightier than the sword." The play was adapted into the 1935 film Cardinal Richelieu.[citation needed]
+
+In the 1969 episode "How to Recognise Different Types of Trees from Quite a Long Way Away" from Monty Python's Flying Circus there is the sketch "Court Scene with Cardinal Richelieu" in which Michael Palin in Richelieu's likeness is seen to be doing wildly absurd acts.[84]
+
+In the 1632/Ring of Fire series by Eric Flint, he is one of the primary antagonists to the nascent United States of Europe.
+
+Many sites and landmarks were named to honor Cardinal Richelieu. They include:[85]
+
+There is also an ornate style of lace, Richelieu lace, named in honor of the cardinal.[86]

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+Medellín (Spanish pronunciation: [meðeˈʝin] or [meðeˈʎin]), officially the Municipality of Medellín (Spanish: Municipio de Medellín), is the second-largest city in Colombia, after Bogotá, and the capital of the department of Antioquia. It is located in the Aburrá Valley, a central region of the Andes Mountains in South America. According to the National Administrative Department of Statistics, the city had an estimated population of 2,508,452 according to the 2018 census.[1] With its surrounding area that includes nine other cities, the metropolitan area of Medellín is the second-largest urban agglomeration in Colombia in terms of population and economy, with more than 3.7 million people.
+
+In 1616 the Spaniard Francisco Herrera Campuzano erected a small indigenous village ("poblado") known as "Saint Lawrence of Aburrá" (San Lorenzo de Aburrá), located in the present-day El Poblado commune. On 2 November 1675, the queen consort Mariana of Austria founded the "Town of Our Lady of Candelaria of Medellín" (Villa de Nuestra Señora de la Candelaria de Medellín) in the Aná region, which today corresponds to the center of the city (east-central zone) and first describes the region as "Medellín". In 1826, the city was named the capital of the Department of Antioquia by the National Congress of the nascent Republic of Gran Colombia, comprised by present-day Colombia, Venezuela, Ecuador, and Panama. After Colombia won its independence from Spain, Medellín became the capital of the Federal State of Antioquia until 1888, with the proclamation of the Colombian Constitution of 1886. During the 19th century, Medellín was a dynamic commercial center, first exporting gold, then producing and exporting coffee.
+
+At the beginning of the 21st century, the city regained industrial dynamism, with the construction of the Medellín Metro commuter rail, liberalized development policies, improved security and improved education. Researchers at the Overseas Development Institute have lauded the city as a pioneer of a post-Washington consensus "local development state" model of economic development.[4]  The city is promoted internationally as a tourist destination and is considered a global city type "Gamma -" by GaWC.[5] The Medellín Metropolitan Area produces 67% of the Department of Antioquia's GDP and 11% of the economy of Colombia.[6] Medellín is important to the region for its universities, academies, commerce, industry, science, health services, flower-growing, and festivals.
+
+In February 2013, the Urban Land Institute chose Medellín as the most innovative city in the world due to its recent advances in politics, education and social development.[7] In the same year, Medellín won the Verónica Rudge Urbanism Award conferred by Harvard University to the Urban Development Enterprise, mainly due to the North-Western Integral Development Project in the city.[8] In September 2013, the United Nations ratified Colombia's petition to host UN-Habitat's 7th World Urban Forum[9] in Medellín, from April 5–11, 2014.[10] In 2016, Medellín won the Lee Kuan Yew World City Prize. The award seeks to recognize and celebrate efforts in furthering innovation in urban solutions and sustainable urban development.[11][12]
+
+The valley and its Spanish settlement have gone by several names over the years, including Aburrá de los Yamesíes, "Valley of Saint Bartholomew", "Saint Lawrence of Aburrá", "Saint Lawrence of Aná", Villa de la Candelaria de Medellín, and finally "Medellín".[13]
+
+The name "Medellín" comes from Medellín, Spain, a small village in the Badajoz province of Extremadura. The village is known for being the birthplace of Hernán Cortés. The Spanish Medellín, in turn, was originally called "Metellinum" and was named after the Roman General Quintus Caecilius Metellus Pius in 75 BC who founded the village as a military base.[14]
+
+Some of the Conquistadors, such as Gaspar de Rodas, the first governor of Antioquia, came from the region of Badajoz. Count Pedro Portocarrero y Luna, President of the Council for the West Indies (Consejo de Indias), asked the Spanish monarchy to give the name of his town, Medellín in Extremadura, to the new settlement in America. His request was accepted on November 22, 1674, when the Regent Mariana of Austria proclaimed the city's name to be Villa de Nuestra Señora de Medellín. Miguel Aguinaga y Mendiogoitia, Governor, made the name official on November 2, 1675. The Crown granted a coat of arms to the city on June 24, 1676.[14]
+
+In August 1541, Marshal Jorge Robledo was in the place known today as Heliconia when he saw in the distance what he thought was a valley. He sent Jerónimo Luis Tejelo to explore the territory, and during the night of August 23, Tejelo reached the plain of what is now Aburrá Valley. The Spaniards gave it the name of "Valley of Saint Bartholomew", but this was soon changed for the native name Aburrá, meaning "Painters", due to the textile decorations of the local chief-men.[15]
+
+In 1574, Gaspar de Rodas asked the Antioquia's Cabildo for 10 square kilometers (4 sq mi) of land to establish herds and a ranch in the valley. The Cabildo granted him 8 square kilometers (3 sq mi) of land.[15]
+
+In 1616, the colonial visitor Francisco de Herrera y Campuzano founded a settlement with 80 Amerindians, naming it Poblado de San Lorenzo, today "El Poblado". In 1646 a colonial law ordered the separation of Amerindians from mestizos and mulattos, so the colonial administration began the construction of a new town in Aná, today Berrío Park, where the church of Nuestra Señora de la Candelaria de Aná ("Our Lady of Candelaria of Aná") was built. Three years later, the Spaniards started the construction of the Basilica of Our Lady of Candelaria, which was rebuilt at the end of the 18th century.[15]
+
+After 1574, with Gaspar de Rodas settled in the valley, the population started to grow. According to the church records of the San Lorenzo Church, six couples married between 1646 and 1650, and 41 between 1671 and 1675.[15] Gold mines were developed northeast of Antioquia, thus they needed food supply from nearby agriculture. The Aburrá Valley was in a strategic position between the gold mines and the first provincial capital of Antioquia, Santa Fe de Antioquia.[15]
+
+The provincial capital, Santa Fe, started to lose importance and gradually became poor, as trade and prominent personalities of the region came to the Aburrá Valley, where rich families started to buy land. Soon, the first settlers asked for the creation of a Cabildo (council) in the valley, thus getting a separate government from Santa Fe.[15] The Santa Fe government fought this, but Mariana of Austria signed the edict creating the Cabildo on November 22, 1674. The governor Miguel de Aguinaga proclaimed the royal edict on 2 November 1675. The new city was given the title of Villa de Nuestra Señora de la Candelaria.[15]
+
+Before the creation of the town, the inhabitants were scattered throughout the valley, with only a few families concentrated at the confluence of the Aná (today called the Santa Elena) and the Medellín rivers; others lived in El Poblado San Lorenzo. After the royal edict, the settlers chose the Aná site as the heart of the future city, with the Candelaria Church at its center.[citation needed]
+
+Their first buildings were simple, with thatched roofs. The houses of the most important people were two stories tall, and the church and the Cabildo were unimpressive. It was only during the 18th century that the church was improved. Only one story, the Cabildo was located at the western part of the plaza. It had a thatched roof until 1742 when tiles were put on. In 1682, traders and foreigners started the construction of the Veracruz Hermitage, which was consecrated as a church by the Bishop of Popayán in 1712.[15]
+
+In 1675, the first census during colonial times was taken: there were 3,000 people and 280 families. Another census was not taken until the colonial Visitador (royal inspector) Antonio Mon y Velarde ordered one between 1786 and 1787: there were then 14,507 people and 241 families. In 1808, two years before Colombia won independence, the city had 15,347 people and 360 families.[15]
+
+In 1803, the Royal College of the Franciscans was founded in the Central Plaza, which is Berrío Park today, with the initial departments of Grammar, Philosophy, and Theology.[16] Soon after, the college moved to a new building in the small San Ignacio square. In 1821 it was renamed Colegio de Antioquia, and it became the University of Antioquia in 1901. The University also had the first vocational training school, the first cultural radio station in Latin America, and the first regional botanical garden.
+
+In the first half of the twentieth century, the population of Medellín increased sixfold, from 59,815 inhabitants in 1905 to 358,189 in 1951. The Thousand Days War (1899–1902) stopped the industrial development of the city, although the civil war did not affect the region directly. Under reforms by President Rafael Reyes after the conflict, the city continued its industrial development[15] and founded a Chamber of commerce.  The Chamber developed a regional transport project that connected Medellín to other Colombian regions and other nations.
+
+Despite the importance of gold production in the early development of Medellín, the export of coffee contributed the most impetus in the 20th century for the city's growth. Trade grew to international dimensions as the main export of Colombia became coffee. The industrial and commercial dynamism of Medellín also created a caste of traders and entrepreneurs, who founded the first nationwide industries in Colombia.[15]
+
+Coltejer is one of the most important textile companies in Colombia. It was founded in Medellín by Alejandro Echavarría on October 22, 1907.[17] Its headquarters, the Coltejer Building, is the tallest skyscraper in Medellín and the fourth tallest building in Colombia.
+
+The discovery of coal in Amagá, a few kilometers south of the Aburrá Valley, and the building of hydroelectric plants provided the new industries with energy, and this allowed the creation of many smaller companies. The Antioquia Railway (built in 1875) conquered the difficult geography of one of the most mountainous regions of South America, notably with the La Quiebra Tunnel, which connected the industrial center to the Magdalena River, the most major navigable river in Colombia. In 1932 Medellín also built its first airport, the Enrique Olaya Herrera Airport.[15]
+
+The study by Charles H. Savage on industrial production in Antioquia between 1960 and 1972 showed how important Medellín industries became to Colombia and South America. He studied social change produced by the introduction of new technology. Savage looked at three factories in Antioquia: two potteries in Santuario and La Blanca, and a tailoring factory in Medellín. Savage studied the production of the Antioquian factories, and the relationship between the workers and their employers, an industrial efficiency which he called the "Culture of Work".[18] His conclusions were published by his colleague George F. Lombardi as Sons of the Machine (1988).[19][20]
+
+Arts and literature have been an important social element in Medellín. The University of Antioquia, the National University of Colombia with its Medellín branch, and the Pontifical Bolivarian University have historically been the academic centers of the city and are responsible for the formation of an intellectual class in the region.
+
+During the first part of the 20th century, the city was part of the literary transition from romanticism to the modern art and literary movements of the new century.[citation needed] The writer Tomás Carrasquilla (1858–1940)  focused on the people of his native Antioquia, portraying their daily lives and customs. The writer and philosopher Fernando González from Envigado (in the metropolitan area of Medellín), the cartoonist Ricardo Rendón and the poet León de Greiff were some of the founders of Los Panidas, a Medellín literary movement. Other featured poets and writers were Porfirio Barba-Jacob and Efe Gómez. In painting, the most famous were Eladio Vélez and Pedro Nel Gómez. Carlos Vieco Ortiz was a popular composer and musician. Medellín became the headquarters of record labels like Sonolux, Ondina and Silver.[15]
+
+Medellín clubs, many of them dating to the end of the 19th century became a center for intellectual and industrialist movements, like Club Union (founded in 1894) and Club Campestre (founded in 1924). In 1909 the Circo España was created, and Bolívar Theater, in 1919. The Junín Theater was demolished to build the Coltejer Tower. Cine Colombia, the first movie distributor of the country, was founded in Medellín in 1927.[15]
+
+Colombia entered a new era of political instability with the murder of presidential candidate Jorge Eliecer Gaitán in Bogotá in 1948. Political violence spread in the rural areas of Colombia, and farmers fled to the cities.[21] The Valley slopes became overpopulated with slums.
+
+As the population of Medellín grew quickly during the 1950s, industrialists, traders and local government created the "Medellín Master Plan" (MMP) (Plan Piloto), a plan for the expansion of the city into the Aburrá Valley that would lead to the creation of the first metropolitan area in Colombia. Paul Lester Wiener and José Luis Sert were the architects who led the project. Among the main features of the MMP were the canalization of the Medellín River, the control of new settlements on valley slopes, the creation of an industrial zone in the Guayabal District, the planning of the city to be in harmony with the river, the construction of a city stadium, and an administrative center in La Alpujarra.[15]
+
+In 1951 the city had 358,189 inhabitants, but 22 years later, in 1973, the population had tripled to 1,071,252.[22] The population explosion had several consequences for the MMP. The urban limits of the city grew to areas that were not contemplated in the MMP, so that Medellín now reached the urban areas of other cities of the Aburrá Valley, like Envigado, Bello and Itagüí; the new Medellín settlers were poor families without enough credit to buy their own homes, so several neighborhoods were built beyond the MMP; several old downtown buildings were demolished to construct tall towers, offices, and avenues.
+
+In 1968 the Second Conference of CELAM was held in Medellin expessing a preferential option for the poor. The traditional Junin Theatre along the Santa Elena was demolished to build the Coltejer Tower. The huge migration into Medellín provided workers for the expansion of textile factories, being modernized in this period,[15] but it also created new problems for the city: higher unemployment, lack of services for poor areas, urban violence in several districts, and collapse of any hope of a transport system.[citation needed]
+
+The position of Medellín as the second industrial city in Colombia has been the main factor in overcoming its crisis of the 1980s and 1990s. The Medellín Metro, a massive urban transport service, became the pride of the city, and so far the only sign of the Medellín Master Plan of the 1950s. The construction of the Plaza Mayor of Medellín, an international center for congresses and expositions, was designed to showcase the globalized economy of Colombia to the world.
+
+Social exclusion has eased due to the development of a transport infrastructure; the Metro, a new system of public buses, is being planned with the so-called "Metroplus", already inaugurated, and gondolas called “MetroCable” in the poorest barrio communities.[4] Additionally, an electric escalator 1,260 feet long was inaugurated on December 26, 2011, in Comuna 13, one of Medellín's poorest neighborhoods, making it one of the first of its kind in the world. Today's Medellín includes spaces for art, poetry, drama, the construction of public libraries, the foundation of new ecological parks, and the inclusion of people of the city in its development.[23]
+
+The city administration has pursued policies that have been lauded by researchers at the Overseas Development Institute as helping pioneer a post-Washington consensus 'local development state' model of economic development.[4]
+
+In 2012, Medellín was among 200 cities around the world, including New York and Tel Aviv, nominated for Most Innovative City of the Year due to a great advancement in public transportation, with more than 500,000 residents and visitors using its Metro train system each day; a public bike-share program; new facilities and landmarks, including the España Library and a cultural center in Moravia; a large outdoor escalator the size of a 28-story building, enabling residents of the city’s elevated Comuna 13 neighborhood to safely ride down the steep hillside; and a Metro system which reduces Medellín’s CO2 emissions by 175,000 tons each year.[24] Medellín has the biggest research-dedicated building in Colombia called University Research Building (Spanish: Sede de Investigación Universitaria, SIU)[25] a facility that concentrates the top research groups of the University of Antioquia.[26]
+
+Medellín has 16 comunas (districts), 5 corregimientos (townships), and 271 barrios (neighborhoods).
+The metropolitan area of Medellín lies within the Aburrá valley at an elevation of 1,500 metres (4,900 feet) above sea level and is bisected by the Medellín River (also called Porce), which flows northward. North of the valley are the towns of Bello, Copacabana, Girardota and Barbosa. To the south of the valley lie Itagüí, Envigado, Sabaneta, La Estrella and Caldas.
+
+The weather in Medellín is warm year-round with few temperature extremes. As a municipality, Medellín has an area of 382 km2 (147 sq mi).  Medellín features a trade-wind tropical rainforest climate (Af), albeit a noticeably cooler version of this climate that borders closely on a subtropical highland climate (Cfb) and also on a tropical monsoon climate (Am). Because Medellín is located at 1,500 m (4,900 ft) above sea level, its climate is not as hot as other cities located at the same latitude near the equator. Because of its altitude above sea level and privileged location in the Andes Range, Medellín's weather at times is more characteristic of a humid subtropical climate than that of a tropical climate. The city's average annual temperature is 22 °C (72 °F), and because of its proximity to the equator, its temperature is constant year-round, with minimal temperature variations. Temperatures range from 15 to 30 °C (59 to 86 °F). Because of the pleasant springlike climate all year, Medellín is known as "La Ciudad de la Eterna Primavera" or "City of the Eternal Spring". However, as the city is located in a valley and many of its districts are on slopes, temperatures can be slightly cooler on the surrounding mountains.
+
+Medellín is a city governed by a republican democratic system as stated in the Colombian Constitution of 1991, with decentralized government. Administration is shared by the Mayor of Medellín and the Municipal Council, both elected by popular vote.
+The municipality is made up of official departments (secretarías) including departments for social mobility, urban culture, social development, education, evaluation and control, government, resources, public works, administrative services, environment, women, and transportation. There are also many departments with a certain autonomy: the Olaya Herrera Airport, the Public Library (Biblioteca Pública Piloto), the College of Antioquia (Colegio Mayor), the Urban Development Enterprise (EDU), the Public Service Enterprise (EPM), the Sport and Recreation Institute (INDER), the General Enterprises of Medellín (EEVVM), the Medellín Bus stations, the General Hospital of Medellín, the health service enterprise "Metrosalud", the Metropolitan Institute of Technology (ITM), the Metro de Medellín, the Department for the Administration of the Medellín parks (Metroparques) and Metroseguridad.
+
+The municipality is divided into six zones: The urban zone, which is subdivided into 16 comunas (communes).  The communes are further divided into 249 statistical neighborhoods. The remaining zones outside the urban zones comprise five corregimientos (townships).
+
+Further, the municipality belongs to the Medellín Metropolitan Area, which is made up of ten neighboring municipalities.
+
+The government of the city of Medellín is divided into executive and legislative branches. The mayor of the city (Alcalde) is publicly elected for a term of four years (just like the president and the governor of any other department in Colombia).
+
+Low tax rates mean Medellín's city administration's social and economic development policies have been funded by the city's ownership of the main energy supplier, Empresas Publicas de Medellín (EPM); 30% of its profits go directly to the city's administrative budget.[4] In addition to infrastructure projects, the city administration has developed a program of cash grants called 'the Medellín Solidaria' programme that is very similar to Brazil's highly successful Bolsa Familia and also the city runs the Cultura E programme.[4]
+
+According to the city administration, Medellín Solidaria represents an improvement on Colombia's national programme, 'Familias en Accion' (Families in Action).[4] The city administration is further responsible for coordinating more than 100 other social programmes.[4] Under the Cultura E programme, the city administration has established a network of 14 publicly funded business support centres known as CEDEZO, Centros de Desarrollo Empresarial Zonal).[4] The CEDEZOs are found in the poorest areas of Medellín and support the poor in developing business by providing free-of-charge business support services and technical advice.[4]
+
+Also, as part of Cultura E, there is Banco de las Oportunidades that provides microloans (up to $2,500 at a cheap interest rate of 0.91% monthly).[4] This has helped create more equal opportunities for all and overcome the barriers to entry to business for poor entrepreneurs with good ideas, but lacking capital, skills and connections.[4] It has also helped develop the local economy with new micro-enterprises.[4]
+
+However, several mayoral candidates for the October 2011 elections have argued the Banco de las Oportunidades's interest rates are too high, loan maturity is too short and it should have grace periods.[4] They, therefore, suggest a new small and medium-sized enterprise (SME) development bank to complement the Banco de las Oportunidades.
+
+Medellín was once known as the most dangerous city in the world,[30][31] a result of an urban war set off by the drug cartels at the end of the 1980s. As the home of the Medellín Cartel funded by Pablo Escobar, the city was a victim of the terror caused by the war between the organization headed by Escobar, and competing organizations such as "El Cartel del Valle". However, after the death of Escobar, crime rates in the city have decreased dramatically.[32]
+
+Throughout the rest of the 1990s crime rates remained relatively high, although gradually declining from the worst years.  In October 2002, President Álvaro Uribe ordered the military to carry out "Operation Orion", the objective of which was to disband the urban militias of the FARC and the AUC.[32] Between 2003 and 2006 the demobilization of the remaining urban militias of the AUC was completed, with more than 3,000 armed men giving up their weapons.[33]
+
+Nonetheless, after the disbanding of the main paramilitary groups, many members of such organizations have been known to have reorganized into criminal bands known commonly as Aguilas Negras ("Black Eagles"). These groups have gained notoriety in Medellín for calling upon curfews for the underage population, and have been known to distribute fliers announcing the social cleansing of prostitutes, drug addicts, and alcoholics.[34] The extradition of paramilitary leader Don Berna appears to have sparked a crime wave with a sharp increase in killings.[35]
+
+As home of the now defunct Medellín Cartel, the city was once known as the most violent city in the world.[30] However, its homicide rate has decreased by 95% and extreme poverty by 66%, thanks in part to a string of innovative mayors who laid out plans to integrate the poorest and most violent hillside neighborhoods into the city center in the valley below. Medellín is now considered safer than the US cities of Baltimore, St. Louis, Detroit and New Orleans, which appear in the CCSPJP's top 50 list.[36]
+
+There is a significant disparity in crime rates by neighborhoods, with virtually no homicides in El Poblado to areas with open gunfights in the outskirts. Generally, crime rates increase the further the neighborhood is from the center.[37] From 2010 and 2011, homicides have declined as with crime in general, but there remains a high crime rate in the poorest communities.
+
+3.2 percent of street addresses account for 97 percent of homicides.[38] More than half of the violent deaths are attributed to clashes between criminal gangs in certain parts of the city. In 1991 there were 7,273 murders at a rate of 266 per 100,000 people; in 2017 had suffered 577 murders at a rate of 23 per 100,000 inhabitants. In the city there are more than 1,100 security cameras and more than 7,000 policemen.[39][40]
+
+Medellín is one of Colombia's economic centers. Its economy is led by a powerful group of people from the private sector known as the Grupo Empresarial Antioqueño (Antioquian Enterprises Group). The group was formerly known as the Sindicato Antioqueño (Antioquian Union) but after being mistaken abroad for a labor union, which hampered its international growth for many years, a new formal name was chosen. It is represented by David Bojanini, head of Grupo Suramericana (a banking, asset management and insurance conglomerate); Carlos Ignacio Gallego of Grupo Nutresa (food industry); José Alberto Velez of Cementos Argos (a multinational cement company); and Carlos Raúl Yepes, head of Bancolombia. This group has an aggregate market capitalization of approximately US $17 billion and employs more than 80,000 Colombians.[41]
+
+This group also participates in other sectors of the city industry and is an active trader in the Colombian stock exchange. Medellín serves as headquarters for many national and multinational companies.
+
+Medellín's main economic products are steel, textiles, confections, food and beverage, agriculture (from its rural area), public services, chemical products, pharmaceuticals, refined oil, and flowers. Fashion is a major part of the economy and culture of the city. Medellín hosts Latin America's biggest fashion show, Colombiamoda.
+
+Aerolínea de Antioquia has its headquarters on the grounds of Enrique Olaya Herrera Airport in Medellín.[42] West Caribbean Airways had its headquarters on the grounds of Olaya Herrera Airport.[43] ACES Colombia was headquartered in the city.[44] VivaColombia, the only low-cost Colombian airline, has its hub at Rionegro's Airport.
+
+The Metropolitan Area of Medellín contributes 67% of the total GDP of the Department of Antioquia and 11% of the economy of Colombia.[6] Antioquia is the second-greatest economic region of Colombia. By 2005, Antioquia's GDP was more than US$14,700,000,000 and the top exporting province in Colombia.[46] The Aburrá Valley is the top economy in the province, and its GDP was $7,800 million.[6] Medellín is the second-largest economic region in Colombia, after Bogotá.
+
+The 2005 Report of the Economic Colombian Review of Proexport and the International Cooperation Agency of Medellín concluded that Medellín was at the same level of GDP contribution to the national economy as cities like Panama City in Panama, and San José de Costa Rica.
+
+Medellín created the first Colombian business cluster. The city is the top exporting region of the country, with 1,750 export businesses based in Medellín.[46] The Cluster was created with the support of the Chamber of Commerce of Medellín and the City Administration for an actual total of 21,000 companies that share 40% of total exports, 25% of the regional GDP, and 40% of Metro Area employment.[46] The main economic activities of the Medellín Cluster (MC) are in electricity generation, textile, fashion design, construction, tourism and business.[47] One goal of the Medellín Cluster is to include health services, an important sector in the local economy.
+
+Ruta N is a non-profit in Medellín which helps foreign companies set up office in Medellín.
+
+According to data released by the Measuring Monetary Poverty and Inequality Mission (Spanish: Misión para el Empalme de las Series de Empleo, Pobreza y Desigualdad, MESEP), in November 2009, the poverty rate in Medellín and its metropolitan area was reduced by 22.5%, from 49.7% to 38.5% during the period from 2002 to 2008. Similarly, the extreme poverty rate decreased by 25.2%, from 12.3% to 9.2%. These results are in line with the increased coverage of basic services such as health, education, and public services in the city. In 2014, the poverty rate decreased to 14.7% and extreme poverty to 2.8%.[48]
+
+The unemployment rate in Medellín and its metropolitan area, as has been the case in Colombia as a whole, has decreased in the past decade. According to data from the National Statistics Department (Spanish: Departamento Administrativo Nacional de Estadística, DANE) unemployment for Medellín and its Metropolitan Area was reduced by 25%, from 14.1%,[49] just above the national average of 13.9% in 2005 to 10.6%,[50] above the national average of 9.9%, in 2015. However, according to DANE, in 2014 Medellín stood out as one of the most unequal cities of Colombia, with a GINI coefficient of 0.506.[48]
+
+There are signs of heavy urban development within the city of Medellín, particularly with the construction of new skyscrapers. Medellín is outpacing all other major Colombian cities, including Bogotá, in the construction and proposed development of new high-rises. As of October 2016, there were 10 skyscrapers, 410 high-rises, 119 buildings under construction in Medellín, including 48 being planned.[51] Other projects that the city has planned are extensions of the cities metro system to nearby suburbs such as Sabaneta. Under construction, the new project is set to open to the public soon.
+
+Medellín was awarded 2013 "Innovative City of the Year" by the Wall Street Journal[52] on March 1 after beating out New York City and Tel Aviv.[53]
+
+When Sergio Fajardo became Mayor of Medellín in 2004, the "Medellín, Commitment of all the Citizens" plan for the city was enacted. One of its fundamental axes was described as "Social Urbanism".[54] The final objective of this model was to promote peace and social equity through its urban policies. To accomplish this, priority was given to the areas of the city where bigger social and economic issues were found. The main tool used with this objective was the planning and development of urban projects that would transform the physical environment while promoting profound social and cultural shifts in the communities they were implemented.[55]
+
+The projects were identified and prioritized using six main guidelines as described in the City Plan by the Council of Medellín:[56]
+
+The main objective of these projects is to fight inequity and exclusion. The neighborhoods with the biggest inequity and violence issues are identified and important investments are made in them. There is no previous agenda over what the specific nature of the interventions will finally be since the projects use a communicative approach to define what is best for the community with the active participation of its members.[56] The outcomes will depend on what the neighborhood decides supported by the inclusion of the expertise of city organizations. The projects will have to incorporate all the elements needed to foster development and will be executed simultaneously to assure the biggest impact.
+
+Aside from usual city investment in public infrastructure and as a result of this approach to city development, there were four main concrete projects that were established to help achieve the objectives of peace and social equity based on the guidelines proposed in the Medellín City Plan by the Council of Medellín.[56]
+
+A "library park" (Spanish: Parque biblioteca) is a term first used in Medellín for an urban complex formed by a combination of a library building with ample surrounding green space for public use. These library parks are strategically located in the periphery of the city to address the need for more cultural and education space and public services in less affluent neighborhoods.[57] The development of library complexes and schools is part of an effort at cultural transformation.[58] This project also aims to create centralities inside the intervened areas that help consolidate and give a clearer identity to the communities. They are meant to provide a network of activity centers for the promotion of education, culture, sport, and recreation.
+
+The initial plan in 2009 built five libraries with attached parks to serve underprivileged neighborhoods. This development included the Biblioteca Parque España designed by Giancarlo Mazzanti,.[59][60] and which was named after Spain, who helped fund the construction of one of its buildings. Architects of the other libraries added as part of the program include Ricardo La Rotta Caballero and Hiroshi Naito. The four other libraries added were León de Greiff Library (also known as La Ladera Library Park), San Javier Library Park, Bethlehem Library Park, and La Quintana Library Park.
+
+After the initial 2009 program another five libraries were added to the plan for 2011. These libraries are the Doce de Octubre Library Park for Comunas 5 and 6, Noroccidente; Las Estancias Library Park for Comunas 8, 9, and Centroriental; Parque Biblioteca Guayabal for Comuna 15 and Suroccidente; Parque Biblioteca San Cristóbal] for Corregimiento and Occidente; and Parque Biblioteca San Antonio de Prado for Corregimiento and Sur.[61]
+
+The idea of "library parks" has served as a model for library spaces in other countries, most notably the Manguinhos Library Park in Rio de Janeiro, Brazil.
+
+The Medellín Metropolitan Area Library Network is a set of libraries linked together to share resources, efforts, knowledge and experience to improve the educational and cultural conditions of the community. The network consists of over 100 libraries, 29 of which reside in Medellín.[62] The Library Network includes all of Medellín's library parks, as well as other regional libraries, such as the Public Pilot Library and the EPM Library.
+
+The Library Network was a program created as a metropolitan agreement in 2005 thanks to an alliance of Empresas Públicas de Medellín, its EPM Foundation, the Mayor of Medellín, and the Pilot Public Library. In 2009, the Library Network was awarded the "Access to Learning Award" by the Bill & Melinda Gates Foundation, consisting of one million dollars to the EPM Foundation and the Library Network.[63]
+
+Additional libraries outside of this network include several other private, public, and university libraries.
+
+Medellín in 2013 won the Veronica Rudge Green Prize in Urban Design, awarded by Harvard University, due to PUI Integral Urban Project Northeast area, designed and implemented by Development Corporation Urbano. Medellín retains very little colonial architecture from the nineteenth century. Although the Aburrá Valley was a hotspot in agriculture and livestock throughout the colonial period, their relative wealth is not expressed in an outstanding and Cartagena, Tunja, Popayán and Bogotá civil and religious architecture. This can be explained by the fact that the population of Medellín was not political and administrative center and a place geographically isolated whose elite invested little in the development of monumental architecture. From the end of the colony remain, but with many transformations, the Candelaria Church and the Church of the Veracruz.
+
+The architecture produced in Colombia between 1850 and 1930 is called "Republican". The use of brick and implementation of European historical styles were the main novelty. Enrique Haeusler designed the Guayaquil Bridge in 1879. But it was the French architect Carlos Carré who headlined Republican nineteenth century architecture in Medellín. Carré came to town in 1889 and was hired to design and build the new Episcopal Cathedral and several commercial and residential buildings for different parts of the city, especially in the new neighborhood of Guayaquil. The Metropolitan Cathedral was completed in 1931; also are of authorship Vásquez and Carré buildings, which are located next to Plaza Cisneros. The Medellín Antioquia Railway Station was the work of Enrique Olarte, a work that allowed the definitive urban consolidation in Guayaquil sector. In the twenties Republican architecture reached its peak phase. In this period stand the old Municipal Palace (now the Museum of Antioquia) in 1928, the National Palace and the Palace of Departmental Government (now the Palace of Culture) between 1925 and 1928. The latter two works were designed by the Belgian architect Agustín Goovaerts, both inspired by the Belgian modernist, it applied the Romanesque and Gothic styles respectively. Other works of Goovaerts were the Church of the Sacred Heart (sector Guayaquil), the Church of San Ignacio, among others. The thirties highlighted such constructions of the Prado neighborhood as the Egyptian house and the current Teatro Prado.
+
+The main parks of the city include Berrío Park in the center of the city; Bolívar Park, a little further north and framed by the Metropolitan Cathedral; and others in more residential areas like Bethlehem Park, El Poblado Park, and Laureles Park. Several modern parks are interactive and have had a positive reception from the people because they are not only places of recreation but also of education. These include Barefoot Park, Wishes Park, Explora Park, and Bicentennial Park (which was recently opened to mark the bicentenary of Colombia).
+
+One of the most visited sites is the Arví Ecotourism Park, which has an area of about 20,000 hectares, covers virtually the entire territory of the village of Santa Elena, and runs between the towns of Bello, Copacabana, and Envigado. In its trails, lakes, forests and streams, one can practice various sports and activities like trekking, kayaking, biking, camping, fishing, swimming, sailing rowing, horseback riding, bike tours and picnics. Its promontory position over Medellín offers natural landscapes overlooking over the entire city.[citation needed]
+
+The city is surrounded from above by seven hills, which serve as natural viewpoints of the city and are sites for healthy leisure, recreation, enjoyment, research, sport, culture, education and ecotourism. The hills are El Volador, La Asomadera, Nutibara, Pan de Azúcar, El Salvador, El Picacho and Santo Domingo. In these natural public spaces one can find viewpoints, pre-Hispanic roads, religious icons, culture and Antioquian traditions, bird watching, the most complete herbal living of Aburrá Valley and the remains of early settlers native of Medellín, among other attractions.
+
+Other parks in the city include North Park and Juan Pablo II Park. The Santa Fe Zoo, founded in 1960, has about 1,000 animals from Asia, Africa, and the Americas.
+
+Wishes Park
+
+Botero Plaza
+
+Parque Lleras
+
+Bolívar Park
+
+Bicentennial Park
+
+Medellín is considered a top research city in medicine in Colombia, being an exponent of advanced surgical operations in the country and Latin America. Health clinics and dental centers in Medellín have become pioneers in offering high quality services in several medical areas. The University Hospital San Vicente de Paul, the Pablo Tobon Uribe Hospital, and Clinical Cardiovascular Santa Maria have received national and international recognition as pioneers in organ transplantation.[64]
+
+América Economía magazine ranked Medellín as having eight of the top 100 hospitals and clinics in Latin America. Its highest ranked hospital was Pablo Tobon Uribe Hospital, which ranked in seventh place in 2014.[65] The Pablo Tobon Uribe Hospital is non-profit and private.
+
+Specialized health centres such as San Vicente Foundation hospitals were recognized with the Silver Category of LEED certification. This is the only hospital outside of the United States of America to obtain this certification.[66]
+
+Among the most recognized universities with notable research work in medicine are the University of Antioquia, CES University,[67] and UPB University.
+
+Air pollution caused more than 7,000 deaths in 2016 in the city and represents a significant financial cost due to the treatment of respiratory diseases.[68]
+
+Medellín is also home to over 30 universities. Among the most important public universities are the following:
+
+There are also important technological centers such as the Metropolitan Institute of Technology (ITM), Jaime Isaza Cadavid's Politecnico, and Antioquia Institute of Technology.
+
+During the last decade, the administration of the city has emphasized public education, building schools and libraries in poor quarters. Private schools and colleges have a long tradition in the city, many run by the Catholic Church, private organizations, and foreign institutions. Among them are Gimnasio Internacional de Medellín, The Columbus School (the only SACS-approved school in the city), Theodoro Hertzl School, St. Ignatius Loyola College, Colegio Calasanz, Colegio Colombo Britanico, El Corazonista School, Marymount School, Montemayor Sagrado Corazon, Montessori School, Colegio Fontán, Gimnasio Los Pinares, Gimnasio Los Alcázares, San Jose de la Salle, Instituto Jorge Robledo, the Salesian Technical School Pedro Justo Berrío, Colegio Cumbres, Colegio San Marcos, Liceo Salazar y Herrera, and 'El Sufragio' Salesian School.
+
+Many non-governmental organizations and official organizations support the development of children and youth from poor communities. Ciudad Don Bosco cares for street children.[70] The pacification of the city brought organizations to the poorest quarters to work with youth involved in urban violence, in order to improve their opportunities. Medellín universities, public and private, also played a role, along with official institutions both local and national.
+
+Medellín has two airports, Olaya Herrera Airport (EOH), and José María Córdova Airport (MDE), which is located in the city of Rionegro, 29 kilometres (18 miles) east of the city of Medellín. In 2012 the busiest domestic flight route was between Jose Maria Cordova Airport and Bogotá while the busiest international route was between Jose Maria Cordova Airport and Panama City.
+
+The Jose Maria Cordova Airport receives international flights from important carriers such as American Airlines, Avianca, JetBlue and Lan Airlines, which makes the city accessible from the many regions of America. Avianca, the flag air-carrier of Colombia, has also an important activity at this airport. This airport has direct flights to important international destinations such as Lima, Quito, Mexico City, Madrid, Miami and New York City.
+
+Medellín has two transportation terminals, the North Transportation Terminal and the South Transportation Terminal. The city's public transport system includes diesel buses, taxis, tram and an urban train referred as the Medellín Metro, the only metro system in Colombia.
+
+The Metro connects the city with most of its metropolitan area. It has five lines. Line A goes from Niquía to La Estrella (north to south), while Line B goes from San Antonio to San Javier (downtown to west). In addition, Line K and Line J, an air cable car, locally known as Metrocable, serve a depressed and geographically difficult area. Line K begins at Acevedo Station on Metro Line A, and continues uphill, ending at Santo Domingo Savio. Line J begins at San Javier Station on Metro Line B, and continues uphill to La Aurora. Line L does not serve communal areas, rather, it is a tourist-oriented line which is connected to Arví Park and is part of a social project to bring retreats and nature to the masses.[71] Colombia has become Latin America's largest user of such complementary transportation service throughout the country.
+
+In 2006, construction began on Metroplús, a bus rapid transit service with a dedicated road, much like Bogotá's TransMilenio, to allow faster transit for the service's buses. The first line opened two years later than planned in 2011 and a second in 2013.[72] The first leg is the Troncal Medellín, which goes from the Universidad de Medellín in the west to Aranjuez in the northeast part of the city. Metroplus will help lessen the city's pollution and traffic, as many old buses will be taken out of service, while the new buses will work with natural gas.[73]
+
+Because of its projects on sustainable transport, the city obtained, along with San Francisco, the 2012 Sustainable Transport Award, given by the Institute for Transport and Development Policy.[74] According to EMBARQ Director Holger Dalkmann, "Medellín pioneered the use of cable cars as a transit alternative in low-income informal settlements in hilly areas, moving 3,000 passengers per hour per direction; a real breakthrough now being replicated in Caracas and Rio de Janeiro,"
+
+The Colombia and Latin America's second-largest and most modern tunnel, the Western Tunnel, officially named the Fernando Gomez Martinez Tunnel, is located between Medellín and Santa Fe de Antioquia. It is 4.6 km (3 mi) in length and offers security and service technologies for the users. It was inaugurated on January 20, 2006.[75][76]
+
+Originally, trams in Medellin were the most important transportation until 1950, but, after that, the rapidly increasing population and number of automobiles forcefully closed it in 1951. However, more than 60 years later, a new Translohr system (rubber-tired "tram"), the Ayacucho Tram, the first modern "tram" in Colombia, was opened on September 30, 2015. It is integrated with the metro system and the local bus network.
+
+The average amount of time people spend commuting with public transit in Medellín, for example to and from work, on a weekday is 66 min. 12% of public transit riders, ride for more than 2 hours every day. The average amount of time people wait at a stop or station for public transit is 11 min, while 14.% of riders wait for over 20 minutes on average every day. The average distance people usually ride in a single trip with public transit is 5.9 km, while 5% travel for over 12 km in a single direction.[77]
+
+The Aburrá Valley contains 58% of the population of the Department of Antioquia, and 67% of the Aburrá Valley population lives in the city of Medellín. Of the inhabitants of Medellín, 61.3% were born in the city, 38% in other parts of Colombia and 0.3% in another country.[79]
+
+According to the National Administrative Department of Statistics, Medellín had, by 2005, a population of 2,223,078 inhabitants, making it the second largest city in Colombia. The metropolitan area of Medellín in 2005 included 3,312,165 inhabitants. There are 5820 people per square kilometer in the city. There were 130,031 people living in the city townships; 46.7% of the population are male and 53.3% are female. Illiteracy is 9.8% in persons older than 5 years old. 98.8% of the households in Medellín have electricity, 97.3% have drinking water, and 91% have a land-line phone.[79]
+
+According to the 2005 DANE census, in that year Medellín registered 33,307 births,[80] slightly fewer than in 2004 (33,615). In 2005 the number of deaths was 10,828, in 2004 11,512.
+
+According to figures submitted by the DANE census 2005,[81] the ethnographic makeup of the city is:
+
+During the 17th and 18th centuries, Medellín received many immigrants from Spain[citation needed]. Most Indigenous peoples died from the introduction of European diseases, and many of those who survived intermarried with early Spanish settlers, who were mostly men; later, Spanish women also began to immigrate. During the 19th and 20th centuries, immigrants arrived from Lebanon, Jordan, Germany, Italy and Portugal. Many people from Medellín are referred to as Paisas, people of mainly Spanish ancestry, a lot of them Basque. There is a small Afro-Colombian and Zambo-Colombian (people of Indigenous and African descent) population.
+
+The Chocó Department is just west of Antioquia, and is home to many Afro-Colombian and Zambo-Colombian migrants to Medellín and its vicinity. Migration from the Colombian Caribbean coast has been important, especially that of young people who come to study in Medellín universities and remain to work in the city. The main foreign immigration is of Ecuadorians in informal trade.
+
+The culture in Medellín is strongly linked to a broader Paisa culture (see next section) whose unique attributes include their Spanish accent, cuisine, and hospitality. Today, Medellín has several cultural attractions for the public including approximately 40 museums, 21 public parks, 28 theaters, and several public libraries.[82] The city also contains several National Monuments of Colombia.
+
+Most people in Medellín are Catholic, as reflected by Medellín's several churches and religious activities. Among the most representative churches are the Metropolitan Cathedral, the largest cathedral in the world built entirely in baked brick. There is also the Basilica of Our Lady of Candelaria, which was the official cathedral until 1931, the Church of San Ignacio, Baroque on the outside and Colonial on inside, the Church of San José, the Church of San Antonio, which has one of the biggest domes in Colombia, the Church of San José del Poblado, located in the Parque del Poblado where the first European settlement in the Aburrá Valley was founded in 1616, and the Church of Nuestra Señora de Belén. All of these temples have religious art and are located in the center of the city, which facilitates their journeys.
+
+In December, the city is covered with thousands of fairy lights, creating the famous Alumbrados (Christmas lights), which are considered by the National Geographic as one of the ten most beautiful in the world,[83] and which can be seen mainly on La Playa Avenue and the Medellín River.
+
+Plaza Mayor is the epicenter of large events and business. By a decree of the municipal government, between 1980 and 1990 all developments or tall buildings necessarily included a sculpture of a famous artist. That is one reason why Medellín has the largest number of sculptures per square kilometer in Colombia.[citation needed]
+
+Furthermore, the city has several festivals and exhibitions year-round. The silletero tradition is also closely tied to the region and is considered a part of Colombian cultural heritage. Since 1957, this tradition has continued in the Silleta Parade that takes place during the annual Festival of the Flowers, where silletas designed with flower arrangements are carried.
+
+Works of many prominent artists, both local and foreign, can be seen on the streets of the city. Some artists who stand out are the masters Rodrigo Arenas Betancur and Fernando Botero.
+
+The inhabitants of Medellín are often called Antioqueños (people of Antioquia) after their province, rather than Medellínenses (people of Medellín) after their city. They are also often known as Paisas, a name which some suggest comes from the coffee growers. The term Paisa comes from the word paisano, meaning "fellow countryman". Paisas make up one of the five different regional cultures within Colombia. In addition to Antioquia, the Paisa region includes the departments of Caldas, Risaralda, Quindio and some towns of Valle del Cauca and Tolima. Although Paisa culture is dominant in Medellín, the so-called "Paisa Capital", the city is becoming more cosmopolitan, now offering music from other regions of Colombia (Vallenato and Chocó), and a variety of restaurants including Chinese, Cuban, and Argentinian.
+
+The Paisa culture has a Spanish background, and is traditionally Catholic, and entrepreneurial.[citation needed] Paisas are said to speak softly and quickly, to smile easily, and to love music, poetry, soccer, bargaining in the markets, and parties. They are proud of their city, and work hard to keep it clean, stemming from the campaign begun in the 1980s, "Depende tambien de ti, darle amor a Medellín" (It depends on you too to give love to Medellín). The Medellín weekend nightlife, in discos, pubs, parks, and certain dedicated streets, is traditionally called rumba.[84]
+
+Medellín has about 40 galleries, which are one of the main attractions of the city. Some of the main museums include the following:
+
+Other prominent museums are Centro Cultural Banco de la República, Entomological Museum Francisco Luis Gallego, Casa Museo Santa Fe, Museum of Natural Sciences, Ethnographic Museum Miguel Ángel Builes and the Mother Laura Ethnographic Museum.[88]
+
+Medellin is well known for having great public art, and there are many buildings that have prominent sculptures outside them. In addition to the sculpture park of Fernando Botero, there are many other sculptural gems by a variety of contemporary and modernist artists scattered around the city. They include works by the artist Hugo Zapata amongst others.
+
+The cuisine of Medellín is again tied to the larger culture of Antioquia. A typical regional dish is the bandeja paisa, meaning the "paisa platter", which usually includes beans, rice, pork cracklings (or "chicharrón"), chorizo, a fried egg, patacónes, salad and avocado. It is traditionally served on a tray slab or wood. It is traditional to consume meals with arepas, which are made with cooked, milled, and mixed corn without further ingredients.
+
+For breakfast, it is common to accompany the food with hot chocolate and possibly a slice of cheese to dunk in the drink. Parva is a traditional component of the Antioquian gastronomy as well. This name is given to a wide variety of sweet and savory baked goods, including pan de queso, pan de bono, buñuelos, and pastries.
+
+Other foods that are typical in the region stem from Colombian food industries, such as Postobón Colombian sodas, the regional aguardiente known as Aguardiente Antioqueño, and Jet chocolate bars.
+
+Soccer is the most popular sport and is widely played in the city. Medellín has two professional clubs: Independiente Medellín, founded in 1913, and Atlético Nacional, founded in 1935. Both teams play at the Atanasio Girardot Stadium. The city has a soccer legacy thanks to notable players such as Rene Higuita, Iván Córdoba, Andrés Escobar, and Víctor Aristizábal, among many others. Other notable sportsmen of the city are the professional golfer and PGA Tour player Camilo Villegas, Medillin-born Israeli Olympic show jumping rider Daniel Bluman, and the retired Formula One, Champ Car, and IndyCar driver Roberto Guerrero.
+
+A popular sport in Medellín, and generally throughout Antioquia, is horseback riding; therefore, it has encouraged trade and production of tools and equipments for this activity, such as chairs and horseshoes for export. During the Festival of the Flowers, the cavalcades achieved a Guinness World Record in 1996 and 1999.
+
+The city also has two Colombian professional basketball teams: the Arrieros of Antioquia and the Mountain Academy.
+
+The Atanasio Girardot Sports Complex is the main sports arena complex of the city. It covers an area of 280,000 m2 (3,013,895 sq ft) and encompasses fields and stadiums for practice and competition for 34 sports. This is the headquarters of most professional sports leagues in Medellín. The sports complex has hosted several events, including the 2011 FIFA U-20 World Cup, the 2010 South American Games, and the 2001 Copa América.
+
+In 2011, Medellín hosted the 15th IAAF Pan American Race Walking Cup.  Athletes and teams from the countries in North, South, and Central American as well as the Caribbean Islands participated. In 2013, Medellín hosted the IAAF Pan American Junior Athletics Championships for track and field. Again, athletes and teams from the countries in North, South, and Central America as well as the Caribbean Islands participated. The junior athletes competed as a test trial for the 2018 Summer Youth Olympics.
+
+Medellín bid to host the 2018 Summer Youth Olympics but was defeated by Buenos Aires in the July 4, 2013 vote.[89]
+
+Another representative sport in the city is cycling. Its respective sport venue is the Martin Rodriguez Velodrome, named after Colombian road racing cyclist Martín Emilio Rodríguez. BMX is also catered for, and its main venue is the BMX Track Antonio Roldán Betancur. The retired cycling three-time Tour de France stage winner and World Time-Trial Champion Santiago Botero Echeverry and the Olympic Gold Medalist and multiple BMX World Champion Mariana Pajón Londoño are both from Medellín.
+
+EnCicla is the name of Medellín's bicycle sharing system, the first bike sharing program in Latin America and the only one of its kind in Colombia. It was the shared winner of the Sustainable Transport Award in 2012 along with San Francisco. EnCicla is the result of an agreement between the metropolitan area of the Valley of Aburrá and EAFIT University. EnCicla is integrated within the city's existing infrastructure of cycle routes, mass transit, and public transport systems. It is available from Monday to Friday from 5:30 am to 8 pm from every EnCicla station.
+
+The coat of arms, flag and anthem of the city, has the recognition of official symbols of the municipality of Medellín according to Decree No. 151 of February 20, 2002, and as emblems of the city are part of the corporate image of management municipal, and therefore are present in the acts, events and official media in which these should appear by its representative character.
+
+The Medellín coat of arms is the oldest emblem of the city, having its origins in a grant by King Charles II of Spain by royal decree issued in Madrid on March 31 of 1678:
+
+...On a blue field shield, a very thick and round tower, battlemented, an inescutcheon of fifteen parts – seven blue and eight gold, on each of the sides a smaller tower, and in between them an image of Our Lady on a cloud with her son in her arms...
+
+However, a more refined and structured in heraldic language, though not official, would be:
+
+In an Azure field, a round tower of gold stands, masoned and clarified by sable, with a checkered escutcheon of 15 pieces – 7 blue and 8 gold (coat of arms of House of Portocarrero) – stamped with an ancient crown of gold between its two towers, with a cloud upon which stands the image of Our Lady of Candelaria carrying the Child in her left arm, a candle in her right hand, radiant, she is flanked by forming clouds from each county.
+
+The blazon has remained over time since it was granted, without further changes to the aesthetics, it is noteworthy that there are different stylistic versions between the Mayor and City Council also meets aesthetic not heraldic standards.
+
+To strengthen the links with the region, the municipality adopted the flag of the Department of Antioquia, which was added to the coat of arms of the city, so that these could make difference. The flag consists of two horizontal stripes of equal proportions, the white top and green bottom, and in the middle between two strips is located the coat. The white color symbolizes purity, integrity, obedience, firmness and eloquence. The green represents hope, abundance, freedom and faith.
+
+The anthem of the city of Medellín is "Anthem of Antioquia", according to Decree No. 151 of February 20, 2002, Article 10, which says: "Anthem of Medellín. To unify the ideals of the region the Antioquia anthem is adopted (lyrics by Epifanio Mejia and music by Gonzalo Vidal) as the Anthem of the Municipality of Medellín. It will be sung in all official functions where the Mayor of Medellín is present."
+
+Medellín is twinned with:
+
+Basilica of Our Lady of Candelaria
+
+San Ignacio Square
+
+La Alpujarra Administrative Center
+
+Downtown Medellín
+
+Pilot Public Library
+
+Christmas lights at Nutibara Hill
+
+Botanical Garden of Medellín
+
+Paraninfo University of Antioquia
+
+Antique Railway Station
+
+Palace of the Fine Arts
+
+International Center of Business CIC
+
+Metropolitan Cathedral
+
+Metropolitan Theatre
+
+Wishes Park
+
+Barefoot Park
+
+Estadio station
+
+Parque Explora
+
+Pueblito Paisa
+
+EAFIT University
+
+Headquarters of Hewlett-Packard in Route N

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+MediaWiki is a free and open-source wiki engine. It was developed for use on Wikipedia in 2002, and given the name "MediaWiki" in 2003.[6] It remains in use on Wikipedia and almost all other Wikimedia websites, including Wiktionary, Wikimedia Commons and Wikidata; these sites continue to define a large part of the requirement set for MediaWiki.[7] MediaWiki was originally developed by Magnus Manske and improved by Lee Daniel Crocker.[8][9] Its development has since then been coordinated by the Wikimedia Foundation.
+
+MediaWiki is written in the PHP programming language and stores all text content into a database. The software is optimized to efficiently handle large projects, which can have terabytes of content and hundreds of thousands of hits per second.[7][10] Because Wikipedia is one of the world's largest websites, achieving scalability through multiple layers of caching and database replication has been a major concern for developers. Another major aspect of MediaWiki is its internationalization; its interface is available in more than 300 languages.[11] The software has more than 1,000 configuration settings[12] and more than 1,800 extensions available for enabling various features to be added or changed.[13]
+
+Besides its use on Wikimedia sites, MediaWiki has been used as a knowledge management and content management system on many thousands of websites, public and private, including the websites Fandom, wikiHow and Gamepedia, and major internal installations like Intellipedia and Diplopedia.
+
+MediaWiki is free and open-source software and is distributed under the terms of the GNU General Public License version 2 or any later version. Its documentation, located at www.mediawiki.org, is released under the Creative Commons BY-SA 3.0 license and partly in the public domain.[14] Specifically, the manuals and other content at MediaWiki.org are Creative Commons-licensed, while the set of help pages intended to be freely copied into fresh wiki installations and/or distributed with MediaWiki software is public domain. This was done to eliminate legal issues arising from the help pages being imported into wikis with licenses that are incompatible with the Creative Commons license.[15] MediaWiki development has generally favored the use of open-source media formats.[16]
+
+MediaWiki has an active volunteer community for development and maintenance. Users who have made meaningful contributions to the project by submitting patches are generally, upon request, granted access to commit revisions to the project's Git/Gerrit repository.[17]
+There are also paid programmers who primarily develop projects for the Wikimedia Foundation. MediaWiki developers participate in the Google Summer of Code by facilitating the assignment of mentors to students wishing to work on MediaWiki core and extension projects.[18]
+During the year prior to November 2012, there were about two hundred developers who had committed changes to the MediaWiki core or extensions.[19]
+Major MediaWiki releases are generated approximately every six months by taking snapshots of the development branch, which is kept continuously in a runnable state;[20] minor releases, or point releases, are issued as needed to correct bugs (especially security problems).
+
+MediaWiki also has a public bug tracker, phabricator.wikimedia.org, which runs Phabricator. The site is also used for feature and enhancement requests.
+
+When Wikipedia was launched in January 2001, it ran on the existing wiki software, UseModWiki. UseModWiki is written in the Perl programming language, and stores all wiki pages, in text (.txt) files. This software soon proved to be limiting, in both functionality and performance. In mid-2001, Magnus Manske — a developer and student at the University of Cologne, as well as, a Wikipedia editor — began working on new software that would replace UseModWiki, specifically designed for use by Wikipedia. This software was written in the PHP scripting language, and stored all of its information in a MySQL engine database. The new software was largely developed by August 24, 2001, and a test wiki for it was established shortly thereafter.
+
+The first, full–implementation of this software, was the new Meta Wikipedia on November 9, 2001. There was a desire to have it implemented immediately on the English-language Wikipedia,[21] however, Manske was apprehensive about any potential bugs harming the nascent website during the period of the final exams he had to complete immediately prior to Christmas;[22] this led to the launch on the English-language Wikipedia being delayed until January 25, 2002. The software was then, gradually, deployed on all the Wikipedia language sites of that time. This software was referred to as "the PHP script" and as "phase II", with the name "phase I", retroactively given to the use of UseModWiki.
+
+Increasing usage soon caused load problems to arise again, and soon after, another rewrite of the software began; this time being done by Lee Daniel Crocker, which became known as "phase III". This new software was also written in PHP, with a MySQL back-end, and kept the basic interface of the phase II software, but with the added functionality of a wider scalability. The "phase III" software went live on Wikipedia in July 2002.
+
+The Wikimedia Foundation was announced on June 20, 2003. In July, Wikipedia contributor Daniel Mayer, suggested the name "MediaWiki" for the software, as a play on "Wikimedia".[23] The MediaWiki name, was gradually phased in, beginning in August 2003. The name has frequently caused confusion due to its (intentional) similarity to the "Wikimedia" name (which itself is similar to "Wikipedia").[24]
+
+The product logo was created by Erik Möller, using a flower photograph taken by Florence Nibart-Devouard, and was originally submitted to the logo contest for a new Wikipedia logo, held in from July 20 to August 27, 2003.[25][26] The logo came in 3rd place, and was chosen to represent MediaWiki rather than Wikipedia, with the 2nd place logo being used for the Wikimedia Foundation.[27] The double square brackets ([[ ]]) symbolize the syntax MediaWiki uses for creating hyperlinks to other wiki pages; while the sunflower, represents the: diversity of content on Wikipedia, the constant growth, and also the wildness.[28]
+
+Later, Brion Vibber, the Chief Technical Officer of the Wikimedia Foundation,[29] took up the role of Release Manager, and the most active Developer.[6][30]
+
+Major milestones in MediaWiki's development have included: the categorization system (2004); Parser Functions, (2006); Flagged Revisions, (2008);[31] the "ResourceLoader", a delivery system for CSS and JavaScript (2011);[32] and the VisualEditor, a "what you see is what you get" (WYSIWYG) editing platform (2013).[33]
+
+The first version of MediaWiki, 1.1, was released in December 2003.
+
+MediaWiki's most famous use has been in Wikipedia and, to a lesser degree, the Wikimedia Foundation's other projects. Fandom, a wiki hosting service formerly known as Wikia, runs on MediaWiki. Other public wikis that run on MediaWiki include wikiHow and SNPedia. WikiLeaks began as a MediaWiki-based site, but is no longer a wiki.
+
+A number of alternative wiki encyclopedias to Wikipedia run on MediaWiki, including Citizendium, Metapedia, Scholarpedia and Conservapedia. MediaWiki is also used internally by a large number of companies, including Novell and Intel.[34][35]
+
+Notable usages of MediaWiki within governments include Intellipedia, used by the United States Intelligence Community, Diplopedia, used by the United States Department of State, and milWiki, a part of milSuite used by the United States Department of Defense. United Nations agencies such as the United Nations Development Programme and INSTRAW chose to implement their wikis using MediaWiki, because "this software runs Wikipedia and is therefore guaranteed to be thoroughly tested, will continue to be developed well into the future, and future technicians on these wikis will be more likely to have exposure to MediaWiki than any other wiki software."[36]
+
+The Free Software Foundation uses MediaWiki to implement the LibrePlanet site.[37]
+
+MediaWiki provides a rich core feature set and a mechanism to attach extensions to provide additional functionality.
+
+Due to the strong emphasis on multilingualism in the Wikimedia projects, internationalization and localization has received significant attention by developers. The user interface has been fully or partially translated into more than 300 languages on translatewiki.net,[11] and can be further customized by site administrators (the entire interface is editable through the wiki).
+
+Several extensions, most notably those collected in the MediaWiki Language Extension Bundle, are designed to further enhance the multilingualism and internationalization of MediaWiki.
+
+Installation of MediaWiki requires that the user have administrative privileges on a server running both PHP and a compatible type of SQL database. Some users find that setting up a virtual host is helpful if the majority of one's site runs under a framework (such as Zope or Ruby on Rails) that is largely incompatible with MediaWiki.[38] Cloud hosting can eliminate the need to deploy a new server.[39]
+
+An installation PHP script is accessed via a web browser to initialize the wiki's settings. It prompts the user for a minimal set of required parameters, leaving further changes, such as enabling uploads,[40] adding a site logo,[41] and installing extensions, to be made by modifying configuration settings contained in a file called LocalSettings.php.[42] Some aspects of MediaWiki can be configured through special pages or by editing certain pages; for instance, abuse filters can be configured through a special page,[43] and certain gadgets can be added by creating JavaScript pages in the MediaWiki namespace.[44] The MediaWiki community publishes a comprehensive installation guide.[45]
+
+One of the earliest differences between MediaWiki (and its predecessor, UseModWiki) and other wiki engines was the use of "free links" instead of CamelCase. When MediaWiki was created, it was typical for wikis to require text like "WorldWideWeb" to create a link to a page about the World Wide Web; links in MediaWiki, on the other hand, are created by surrounding words with double square brackets, and any spaces between them are left intact, e.g. [[World Wide Web]]. This change was logical for the purpose of creating an encyclopedia, where accuracy in titles is important.
+
+MediaWiki uses an extensible[46] lightweight wiki markup designed to be easier to use and learn than HTML. Tools exist for converting content such as tables between MediaWiki markup and HTML.[47] Efforts have been made to create a MediaWiki markup spec, but a consensus seems to have been reached that Wikicode requires context-sensitive grammar rules.[48][49] The following side-by-side comparison illustrates the differences between wiki markup and HTML:
+
+"Take some more tea," the March Hare said to Alice, very earnestly.
+
+"I've had nothing yet," Alice replied in an offended tone: "so I can't take more."
+
+"You mean you can't take less," said the Hatter: "it's very easy to take more than nothing."
+
+(Quotation above from Alice's Adventures in Wonderland by Lewis Carroll)
+
+MediaWiki's default page-editing tools have been described as somewhat challenging to learn.[50] A survey of students assigned to use a MediaWiki-based wiki found that when they were asked an open question about main problems with the wiki, 24% cited technical problems with formatting, e.g. "Couldn't figure out how to get an image in. Can't figure out how to show a link with words; it inserts a number."[51]
+
+To make editing long pages easier, MediaWiki allows the editing of a subsection of a page (as identified by its header). A registered user can also indicate whether or not an edit is minor. Correcting spelling, grammar or punctuation are examples of minor edits, whereas adding paragraphs of new text is an example of a non-minor edit.
+
+Sometimes while one user is editing, a second user saves an edit to the same part of the page. Then, when the first user attempts to save the page, an edit conflict occurs. The second user is then given an opportunity to merge their content into the page as it now exists following the first user's page save.
+
+MediaWiki's user interface has been localized in many different languages. A language for the wiki content itself can also be set, to be sent in the "Content-Language" HTTP header and "lang" HTML attribute.
+
+MediaWiki has an extensible web API (application programming interface) that provides direct, high-level access to the data contained in the MediaWiki databases. Client programs can use the API to log in, get data, and post changes. The API supports thin web-based JavaScript clients and end-user applications (such as vandal-fighting tools). The API can be accessed by the backend of another web site.[52] An extensive Python bot library, Pywikibot,[53] and a popular semi-automated tool called AutoWikiBrowser, also interface with the API.[54] The API is accessed via URLs such as http://en.wikipedia.org/w/api.php?action=query&list=recentchanges. In this case, the query would be asking Wikipedia for information relating to the last 10 edits to the site. One of the perceived advantages of the API is its language independence; it listens for HTTP connections from clients and can send a response in a variety of formats, such as XML, serialized PHP, or JSON.[55] Client code has been developed to provide layers of abstraction to the API.[56]
+
+MediaWiki supports rich content generated through specialized syntax. For example, the software comes with optional support for rendering mathematical formulas using LaTeX and a special parser written in OCaml. Similar functionality for other content, ranging from graphical timelines over mathematical plotting and musical scores to Egyptian hieroglyphs, is available via extensions.
+
+The software has become more powerful at dealing with a wide variety of uploaded media files. Its richest functionality is in the area of images, where image galleries and thumbnails can be generated with relative ease. There is also support for Exif metadata. The use of MediaWiki to operate the Wikimedia Commons, one of the largest free content media archives, has driven the need for further functionality in this area.
+
+Because any WYSIWYG editor would have to know wikitext grammar, and no full grammar for wikitext exists, MediaWiki currently provides no native WYSIWYG support.[57] It does come with a customizable graphical toolbar for simplifying the process of learning the wiki syntax.[58] Various extensions exist for handling WYSIWYG editing to different degrees.[59]
+
+Among the features of MediaWiki to assist in tracking edits is a Recent Changes feature that provides a list of recent edits to the wiki. This list contains basic information about those edits such as the editing user, the edit summary, the page edited, as well as any tags (e.g. "possible malware link")[60] added by customizable abuse filters and other extensions to aid in combating unhelpful edits.[61] On more active wikis, so many edits occur that it is hard to track Recent Changes manually. Anti-vandal software, including user-assisted tools[62] are sometimes employed on such wikis to process Recent Changes items. Server load can be reduced by sending a continuous feed of Recent Changes to an IRC channel that these tools can monitor, eliminating their need to send requests for a refreshed Recent Changes feed to the API.[63][64]
+
+Another important tool is watchlisting. Each logged-in user has a watchlist to which the user can add whatever pages he or she wishes. When an edit is made to one of those pages, a summary of that edit appears on the watchlist the next time it is refreshed.[65] As with the recent changes page, recent edits that appear on the watchlist contain clickable links for easy review of the article history and specific changes made.
+
+There is also capability to review all edits made by any particular user. In this way, if an edit is identified as problematic, it is possible to check the user's other edits for issues.
+
+MediaWiki allows one to link to specific versions of articles. This has been useful to the scientific community, in that expert peer reviewers could analyse articles, improve them and provide links to the trusted version of that article.[66]
+
+Navigation through the wiki is largely through internal wikilinks. MediaWiki's wikilinks implement page existence detection, in which a link is colored blue if the target page exists on the local wiki and red if it does not. If a user clicks on a red link, they are prompted to create an article with that title. Page existence detection makes it practical for users to create "wikified" articles — that is, articles containing links to other pertinent subjects — without those other articles being yet in existence.
+
+Interwiki links function much the same way as namespaces. A set of interwiki prefixes can be configured to cause, for instance, a page title of wikiquote:Jimbo Wales to direct the user to the Jimbo Wales article on Wikiquote.[67] Unlike internal wikilinks, interwiki links lack page existence detection functionality, and accordingly there is no way to tell whether a blue interwiki link is broken or not.
+
+Page tabs are displayed at the top of pages. These tabs allow users to perform actions or view pages that are related to the current page. The available default actions include viewing, editing, and discussing the current page. The specific tabs displayed depend on whether or not the user is logged into the wiki and whether the user has sysop privileges on the wiki. For instance, the ability to move a page or add it to one's watchlist is usually restricted to logged-in users. The site administrator can add or remove tabs by using JavaScript or installing extensions.[68]
+
+Each page has an associated history page from which the user can access every version of the page that has ever existed and generate diffs between two versions of his choice. Users' contributions are displayed not only here, but also via a "user contributions" option on a sidebar. Carl Challborn & Teresa Reimann note that "While this feature may be a slight deviation from the collaborative, 'ego-less' spirit of wiki purists, it can be
+very useful for educators who need to assess the contribution and participation of individual student users."[69]
+
+MediaWiki provides many features beyond hyperlinks for structuring content. One of the earliest such features is namespaces. One of Wikipedia's earliest problems had been the separation of encyclopedic content from pages pertaining to maintenance and communal discussion, as well as personal pages about encyclopedia editors. Namespaces are prefixes before a page title (such as "User:" or "Talk:") that serve as descriptors for the page's purpose and allow multiple pages with different functions to exist under the same title. For instance, a page titled "[[The Terminator]]", in the default namespace, could describe the 1984 movie starring Arnold Schwarzenegger, while a page titled "[[User:The Terminator]]" could be a profile describing a user who chooses this name as a pseudonym. More commonly, each namespace has an associated "Talk:" namespace, which can be used to discuss its contents, such as "User talk:" or "Template talk:". The purpose of having discussion pages is to allow content to be separated from discussion surrounding the content.[70][71]
+
+Namespaces can be viewed as folders that separate different basic types of information or functionality. Custom namespaces can be added by the site administrators. There are 16 namespaces by default for content, with 2 "pseudo-namespaces" used for dynamically generated "Special:" pages and links to media files. Each namespace on MediaWiki is numbered: content page namespaces have even numbers and their associated talk page namespaces have odd numbers.[72]
+
+Users can create new categories and add pages and files to those categories by appending one or more category tags to the content text. Adding these tags creates links at the bottom of the page that take the reader to the list of all pages in that category, making it easy to browse related articles.[73] The use of categorization to organize content has been described as a combination of:
+
+In addition to namespaces, content can be ordered using subpages. This simple feature provides automatic breadcrumbs of the pattern [[Page title/Subpage title]] from the page after the slash (in this case, "Subpage title") to the page before the slash (in this case, "Page title").
+
+If the feature is enabled, users can customize their stylesheets and configure client-side JavaScript to be executed with every pageview. On Wikipedia, this has led to a large number of additional tools and helpers developed through the wiki and shared among users. For instance, navigation popups is a custom JavaScript tool that shows previews of articles when the user hovers over links, and also provides shortcuts for common maintenance tasks.[75]
+
+The entire MediaWiki user interface can be edited through the wiki itself by users with the necessary permissions (typically called "administrators"). This is done through a special namespace with the prefix "MediaWiki:", where each page title identifies a particular user interface message. Using an extension,[76] it is also possible for a user to create personal scripts, and to choose whether certain sitewide scripts should apply to them by toggling the appropriate options in the user preferences page.
+
+The "MediaWiki:" namespace was also originally used for creating custom text blocks that could then be dynamically loaded into other pages using a special syntax. This content was later moved into its own namespace, "Template:".
+
+Templates are text blocks that can be dynamically loaded inside another page whenever that page is requested. The template is a special link in double curly brackets (for example "{{Disputed|date=October 2018}}"), which calls the template (in this case located at Template:Disputed) to load in place of the template call.
+
+Templates are structured documents containing attribute–value pairs. They are defined with parameters, to which are assigned values when transcluded on an article page. The name of the parameter is delimited from the value by an equals sign. A class of templates known as infoboxes is used on Wikipedia to collect and present a subset of information about its subject, usually on the top (mobile view) or top right-hand corner (desktop view) of the document.
+
+A related method, called template substitution (called by adding subst: at the beginning of a template link) inserts (like a copy and paste operation) the contents of the template into the target page, instead of loading the template contents dynamically whenever the page is loaded. This can lead to inconsistency when using templates, but may be useful in certain cases, and in most cases requires fewer server resources (the actual amount of savings can vary depending on wiki configuration and the complexity of the template).
+
+Templates have found many different uses. Templates enable users to create complex table layouts that are used consistently across multiple pages, and where only the content of the tables gets inserted using template parameters. Templates are often used to identify problems with a Wikipedia article by putting a template in the article. This template then outputs a graphical box stating that the article content is disputed or in need of some other attention, and also categorize it so that articles of this nature can be located. Templates are also used on user pages to send users standard messages welcoming them to the site,[77] giving them awards for outstanding contributions,[78][79] warning them when their behavior is considered inappropriate,[80] notifying them when they are blocked from editing,[81] and so on.
+
+MediaWiki offers flexibility in creating and defining user groups. For instance, it would be possible to create an arbitrary "ninja" group that can block users and delete pages, and whose edits are hidden by default in the recent changes log. It is also possible to set up a group of "autoconfirmed" users that one becomes a member of after making a certain number of edits and waiting a certain number of days.[82] Some groups that are enabled by default are bureaucrats and sysops. Bureaucrats have power to change other users' rights. Sysops have power over page protection and deletion and the blocking of users from editing. MediaWiki's available controls on editing rights have been deemed sufficient for publishing and maintaining important documents such as a manual of standard operating procedures in a hospital.[83]
+
+When a page consists only of useless content, there are several ways to remove that content. The simplest way, available to all users, is simply to blank the page. However, this interferes with page existence detection, unless an extension is installed to treat blanked pages as though they were nonexistent.[84] Blanking also leaves the content accessible through the history page, an outcome that, while potentially increasing transparency by allowing non-sysops to easily review the content removal decision for appropriateness, might be unacceptable or even unlawful[85] in some cases. Another option is for a sysop to delete the page, and thereby prevent it from being viewed by non-sysops. Another level of deletion, called RevisionDelete, can be used by a group (e.g. "Oversighters") to prevent a page from being viewed by non-members of that group.[86] It is also possible, using certain extensions, to remove content from being viewed through any of the normal channels on the wiki,[87] or even to completely delete revisions from the database.[88]
+
+MediaWiki comes with a basic set of features related to restricting access, but its original and ongoing design is driven by functions that largely relate to content, not content segregation. As a result, with minimal exceptions (related to specific tools and their related "Special" pages), page access control has never been a high priority in core development and developers have stated that users requiring secure user access and authorization controls should not rely on MediaWiki, since it was never designed for these kinds of situations. For instance, it is extremely difficult to create a wiki where only certain users can read and access some pages.[89] Here, wiki engines like Foswiki, MoinMoin and Confluence provide more flexibility by supporting advanced security mechanisms like access control lists.
+
+The MediaWiki codebase contains various "hooks" using callback functions to add additional PHP code in an extensible way. This allows developers to write extensions without necessarily needing to modify the core or having to submit their code for review. Installing an extension typically consists of adding a line to the configuration file, though in some cases additional changes such as database updates or core patches are required.
+
+Five main extension points were created to allow developers to add features and functionalities to MediaWiki. Hooks are run every time a certain event happens; for instance, the ArticleSaveComplete hook occurs after a save article request has been processed.[90] This can be used, for example, by an extension that notifies selected users whenever a page edit occurs on the wiki from new or anonymous users.[91] New tags can be created to process data with opening and closing tags (<newtag>...</newtag>).[92] Parser functions can be used to create a new command ({{#if:...|...|...}}).[93] New special pages can be created to perform a specific function. These pages are dynamically generated. For example, a special page might show all pages that have one or more links to an external site or it might create a form providing user submitted feedback.[94] Skins allow users to customize the look and feel of MediaWiki.[95] A minor extension point allows the use of Amazon S3 to host image files.[96]
+
+MediaWiki can be made more advanced and useful for various purposes through its extensions. These extensions vary greatly in complexity.
+
+The Wikimedia Foundation operates a Git server where many extensions host their repository. Most of them also have a documentation page on the MediaWiki website.
+
+MediaWiki code review was itself historically facilitated through a MediaWiki extension.[97] As of March 2012, it has been done through Gerrit.
+
+Since version 1.16, MediaWiki uses the jQuery library.[98]
+
+Among the most popular extensions is a parser function extension, ParserFunctions, which allows different content to be rendered based on the result of conditional statements.[99] These conditional statements can perform functions such as evaluating whether a parameter is empty, comparing strings, evaluating mathematical expressions, and returning one of two values depending on whether a page exists. It was designed as a replacement for a notoriously inefficient template called {{Qif}}.[100] Schindler recounts the history of the ParserFunctions extension as follows:[31]
+
+In 2006 some Wikipedians discovered that through an intricate and complicated interplay of templating features and CSS they could create conditional wiki text, i.e. text that was displayed if a template parameter had a specific value. This included repeated calls of templates within templates, which bogged down the performance of the whole system. The developers faced the choice of either disallowing the spreading of an obviously desired feature by detecting such usage and explicitly disallowing it within the software, or offer an efficient alternative. The latter was done by Tim Starling, who announced the introduction of parser functions, wiki text that calls functions implemented in the underlying software.
+At first, only conditional text and the computation of simple mathematical expressions was implemented, but this already increased the possibilities for wiki editors enormously. With time further parser functions were introduced, finally leading to a framework that allowed the simple writing of extension function to add arbitrary functionalities, like e.g. geo-coding services or widgets. This time the developers were clearly reacting to the demand of the community, being forced either to fight the solution of the issue that the community had (i.e. conditional text), or offer an improved technical implementation to replace the previous practice and achieve an overall better performance.
+
+Another parser functions extension, StringFunctions, was developed to allow evaluation of string length, string position, and so on. Wikimedia communities, having created awkward workarounds to accomplish the same functionality,[101] clamored for it to be enabled on their projects.[102] Much of its functionality was eventually integrated into the ParserFunctions extension,[103] albeit disabled by default and accompanied by a warning from Tim Starling that enabling string functions would allow users "to implement their own parsers in the ugliest, most inefficient programming language known to man: MediaWiki wikitext with ParserFunctions."[104]
+
+Since 2012 an extension, Scribunto, has existed that allows for the creation of "modules" — wiki pages written in the scripting language Lua — which can then be run within templates and standard wiki pages. Scribunto has been installed on Wikipedia and other Wikimedia sites since 2013, and is used heavily on those sites. Scribunto code runs significantly faster than corresponding wikitext code using ParserFunctions.[105]
+
+Another very popular extension is a citation extension that enables footnotes to be added to pages using inline references.[106] This extension has, however, been criticized for being difficult to use and requiring the user to memorize complex syntax. A gadget called RefToolbar attempts to make it easier to create citations using common templates. MediaWiki has some extensions that are well-suited for academia, such as mathematics extensions[107] and an extension that allows molecules to be rendered in 3D.[108]
+
+A generic Widgets extension exists that allows MediaWiki to integrate with virtually anything. Other examples of extensions that could improve a wiki are category suggestion extensions[109] and extensions for inclusion of Flash Videos,[110] YouTube videos,[111] and RSS feeds.[112] Metavid, a site that archives video footage of the U.S. Senate and House floor proceedings, was created using code extending MediaWiki into the domain of collaborative video authoring.[113]
+
+There are many spambots that search the web for MediaWiki installations and add linkspam to them, despite the fact that MediaWiki uses the nofollow attribute to discourage such attempts at search engine optimization.[114] Part of the problem is that third party republishers, such as mirrors, may not independently implement the nofollow tag on their websites, so marketers can still get PageRank benefit by inserting links into pages when those entries appear on third party websites.[115] Anti-spam extensions have been developed to combat the problem by introducing CAPTCHAs,[116] blacklisting certain URLs,[117] and allowing bulk deletion of pages recently added by a particular user.[118]
+
+MediaWiki comes pre-installed with a standard text-based search. Extensions exist to let MediaWiki use more sophisticated third-party search engines, including Elasticsearch (which since 2014 has been in use on Wikipedia), Lucene[119] and Sphinx.[120]
+
+Various MediaWiki extensions have also been created to allow for more complex, faceted search, on both data entered within the wiki and on metadata such as pages' revision history.[121][122] Semantic MediaWiki is one such extension.[123][124]
+
+MediaWiki can use either the MySQL/MariaDB, PostgreSQL or SQLite relational database management system. There is limited support for Oracle Database and Microsoft SQL Server.[125] A MediaWiki database contains several dozen tables, including a page table that contains page titles, page ids, and other metadata;[126] and a revision table to which is added a new row every time an edit is made, containing the page id, a brief textual summary of the change performed, the user name of the article editor (or its IP address the case of an unregistered user) and a timestamp.[127][128]
+
+In a 4½ year period, the MediaWiki database had 170 schema versions.[129] Possibly the largest schema change was done in MediaWiki 1.5, when the storage of metadata was separated from that of content, to improve performance flexibility. When this upgrade was applied to Wikipedia, the site was locked for editing, and the schema was converted to the new version in about 22 hours. Some software enhancement proposals, such as a proposal to allow sections of articles to be watched via watchlist, have been rejected because the necessary schema changes would have required excessive Wikipedia downtime.[130]
+
+Because it is used to run one of the highest-traffic sites on the Web, Wikipedia, MediaWiki's performance and scalability have been highly optimized.[30] MediaWiki supports Squid, load-balanced database replication, client-side caching, memcached or table-based caching for frequently accessed processing of query results, a simple static file cache, feature-reduced operation, revision compression, and a job queue for database operations. MediaWiki developers have attempted to optimize the software by avoiding expensive algorithms, database queries, etc., caching every result that is expensive and has temporal locality of reference, and focusing on the hot spots in the code through profiling.[131]
+
+MediaWiki code is designed to allow for data to be written to a master database and read from slave databases, although the master can be used for some read operations if the slaves are not yet up to date. Metadata, such as article revision history, article relations (links, categories etc.), user accounts and settings can be stored in core databases and cached; the actual revision text, being more rarely used, can be stored as append-only blobs in external storage.  The software is suitable for the operation of large scale wiki farms such as Wikimedia, which had about 800 wikis as of August 2011. However, MediaWiki comes with no built-in GUI to manage such installations.
+
+Empirical evidence shows most revisions in MediaWiki databases tend to differ only slightly from previous revisions. Therefore, subsequent revisions of an article can be concatenated and then compressed, achieving very high data compression ratios of up to 100x.[131]
+
+For more information on the architecture, such as how it stores wikitext and assembles a page, see External links.
+
+The parser serves as the de facto standard for the MediaWiki syntax, as no formal syntax has been defined. Due to this lack of a formal definition, it has been difficult to create WYSIWYG editors for MediaWiki, although several WYSIWYG extensions do exist, including the popular VisualEditor.
+
+MediaWiki is not designed to be a suitable replacement for dedicated online forum or blogging software,[132] although extensions do exist to allow for both of these.[133][134]
+
+It is common for new MediaWiki users to make certain mistakes, such as forgetting to sign posts with four tildes (~~~~),[135] or manually entering a plaintext signature,[136] due to unfamiliarity with the idiosyncratic particulars involved in communication on MediaWiki discussion pages. On the other hand, the format of these discussion pages has been cited as a strength by one educator, who stated that it provides more fine-grain capabilities for discussion than traditional threaded discussion forums. For example, instead of 'replying' to an entire message, the participant in a discussion can create a hyperlink to a new wiki page on any word from the original page. Discussions are easier to follow since the content is available via hyperlinked wiki page, rather than a series of reply messages on a traditional threaded discussion forum. However, except in few cases, students were not using this capability, possibly because of their familiarity with the traditional linear discussion style and a lack of guidance on how to make the content more 'link-rich'.[137]
+
+MediaWiki by default has little support for the creation of dynamically assembled documents, or pages that aggregate data from other pages. Some research has been done on enabling such features directly within MediaWiki.[138] The Semantic MediaWiki extension provides these features. It is not in use on Wikipedia, but in more than 1,600 other MediaWiki installations.[139] The Wikibase Repository and Wikibase Repository client are however implemented in Wikidata and Wikipedia respectively, and to some extent provides semantic web features, and linking of centrally stored data to infoboxes in various Wikipedia articles.
+
+Upgrading MediaWiki is usually fully automated, requiring no changes to the site content or template programming. Historically troubles have been encountered when upgrading from significantly older versions.[140]
+
+MediaWiki developers have enacted security standards, both for core code and extensions.[141] SQL queries and HTML output are usually done through wrapper functions that handle validation, escaping, filtering for prevention of cross-site scripting and SQL injection.[142]  Many security issues have had to be patched after a MediaWiki version release,[143] and accordingly MediaWiki.org states, "The most important security step you can take is to keep your software up to date" by subscribing to the announcement listserv and installing security updates that are announced.[144]
+
+MediaWiki developers are spread around the world, though with a majority in the United States and Europe. Face-to-face meetings and programming sessions for MediaWiki developers have been held once or several times a year since 2004.[145]
+
+Support for MediaWiki users consists of:
+
+Users of online collaboration software are familiar with MediaWiki's functions and layout due to its noted use on Wikipedia. Compared to other wikis, MediaWiki is also fairly aesthetically pleasing, though simple, and has an easily customized side menu and stylesheet.[149] However, in one assessment in 2006, Confluence was deemed to be a superior product due to its very usable API and ability to better support multiple wikis.[108] Wiki providers Socialtext and JotSpot have/had project management features that MediaWiki lacks.[150]
+
+A study was done at the University of Hong Kong comparing TWiki to MediaWiki. The authors noted that TWiki has been considered as a collaborative tool for development of educational papers and technical projects, whereas MediaWiki's most noted use is on Wikipedia. Although both platforms allow discussion and tracking of progress, TWiki has a "Report" part that MediaWiki lacks. Students perceived MediaWiki as being easier to use and more enjoyable than TWiki. When asked whether they recommended using MediaWiki for knowledge management course group project, 15 out of 16 respondents expressed their preference for MediaWiki giving answers of great certainty, such as "of course", "for sure".[151] TWiki and MediaWiki both have flexible plug-in architecture.[152]
+
+A study that compared students' experience with MediaWiki to that with Google Documents found that students gave the latter a much higher rating on user-friendly layout.[153]

en/3752.html.txt

@@ -0,0 +1,190 @@
+
+
+
+
+MediaWiki is a free and open-source wiki engine. It was developed for use on Wikipedia in 2002, and given the name "MediaWiki" in 2003.[6] It remains in use on Wikipedia and almost all other Wikimedia websites, including Wiktionary, Wikimedia Commons and Wikidata; these sites continue to define a large part of the requirement set for MediaWiki.[7] MediaWiki was originally developed by Magnus Manske and improved by Lee Daniel Crocker.[8][9] Its development has since then been coordinated by the Wikimedia Foundation.
+
+MediaWiki is written in the PHP programming language and stores all text content into a database. The software is optimized to efficiently handle large projects, which can have terabytes of content and hundreds of thousands of hits per second.[7][10] Because Wikipedia is one of the world's largest websites, achieving scalability through multiple layers of caching and database replication has been a major concern for developers. Another major aspect of MediaWiki is its internationalization; its interface is available in more than 300 languages.[11] The software has more than 1,000 configuration settings[12] and more than 1,800 extensions available for enabling various features to be added or changed.[13]
+
+Besides its use on Wikimedia sites, MediaWiki has been used as a knowledge management and content management system on many thousands of websites, public and private, including the websites Fandom, wikiHow and Gamepedia, and major internal installations like Intellipedia and Diplopedia.
+
+MediaWiki is free and open-source software and is distributed under the terms of the GNU General Public License version 2 or any later version. Its documentation, located at www.mediawiki.org, is released under the Creative Commons BY-SA 3.0 license and partly in the public domain.[14] Specifically, the manuals and other content at MediaWiki.org are Creative Commons-licensed, while the set of help pages intended to be freely copied into fresh wiki installations and/or distributed with MediaWiki software is public domain. This was done to eliminate legal issues arising from the help pages being imported into wikis with licenses that are incompatible with the Creative Commons license.[15] MediaWiki development has generally favored the use of open-source media formats.[16]
+
+MediaWiki has an active volunteer community for development and maintenance. Users who have made meaningful contributions to the project by submitting patches are generally, upon request, granted access to commit revisions to the project's Git/Gerrit repository.[17]
+There are also paid programmers who primarily develop projects for the Wikimedia Foundation. MediaWiki developers participate in the Google Summer of Code by facilitating the assignment of mentors to students wishing to work on MediaWiki core and extension projects.[18]
+During the year prior to November 2012, there were about two hundred developers who had committed changes to the MediaWiki core or extensions.[19]
+Major MediaWiki releases are generated approximately every six months by taking snapshots of the development branch, which is kept continuously in a runnable state;[20] minor releases, or point releases, are issued as needed to correct bugs (especially security problems).
+
+MediaWiki also has a public bug tracker, phabricator.wikimedia.org, which runs Phabricator. The site is also used for feature and enhancement requests.
+
+When Wikipedia was launched in January 2001, it ran on the existing wiki software, UseModWiki. UseModWiki is written in the Perl programming language, and stores all wiki pages, in text (.txt) files. This software soon proved to be limiting, in both functionality and performance. In mid-2001, Magnus Manske — a developer and student at the University of Cologne, as well as, a Wikipedia editor — began working on new software that would replace UseModWiki, specifically designed for use by Wikipedia. This software was written in the PHP scripting language, and stored all of its information in a MySQL engine database. The new software was largely developed by August 24, 2001, and a test wiki for it was established shortly thereafter.
+
+The first, full–implementation of this software, was the new Meta Wikipedia on November 9, 2001. There was a desire to have it implemented immediately on the English-language Wikipedia,[21] however, Manske was apprehensive about any potential bugs harming the nascent website during the period of the final exams he had to complete immediately prior to Christmas;[22] this led to the launch on the English-language Wikipedia being delayed until January 25, 2002. The software was then, gradually, deployed on all the Wikipedia language sites of that time. This software was referred to as "the PHP script" and as "phase II", with the name "phase I", retroactively given to the use of UseModWiki.
+
+Increasing usage soon caused load problems to arise again, and soon after, another rewrite of the software began; this time being done by Lee Daniel Crocker, which became known as "phase III". This new software was also written in PHP, with a MySQL back-end, and kept the basic interface of the phase II software, but with the added functionality of a wider scalability. The "phase III" software went live on Wikipedia in July 2002.
+
+The Wikimedia Foundation was announced on June 20, 2003. In July, Wikipedia contributor Daniel Mayer, suggested the name "MediaWiki" for the software, as a play on "Wikimedia".[23] The MediaWiki name, was gradually phased in, beginning in August 2003. The name has frequently caused confusion due to its (intentional) similarity to the "Wikimedia" name (which itself is similar to "Wikipedia").[24]
+
+The product logo was created by Erik Möller, using a flower photograph taken by Florence Nibart-Devouard, and was originally submitted to the logo contest for a new Wikipedia logo, held in from July 20 to August 27, 2003.[25][26] The logo came in 3rd place, and was chosen to represent MediaWiki rather than Wikipedia, with the 2nd place logo being used for the Wikimedia Foundation.[27] The double square brackets ([[ ]]) symbolize the syntax MediaWiki uses for creating hyperlinks to other wiki pages; while the sunflower, represents the: diversity of content on Wikipedia, the constant growth, and also the wildness.[28]
+
+Later, Brion Vibber, the Chief Technical Officer of the Wikimedia Foundation,[29] took up the role of Release Manager, and the most active Developer.[6][30]
+
+Major milestones in MediaWiki's development have included: the categorization system (2004); Parser Functions, (2006); Flagged Revisions, (2008);[31] the "ResourceLoader", a delivery system for CSS and JavaScript (2011);[32] and the VisualEditor, a "what you see is what you get" (WYSIWYG) editing platform (2013).[33]
+
+The first version of MediaWiki, 1.1, was released in December 2003.
+
+MediaWiki's most famous use has been in Wikipedia and, to a lesser degree, the Wikimedia Foundation's other projects. Fandom, a wiki hosting service formerly known as Wikia, runs on MediaWiki. Other public wikis that run on MediaWiki include wikiHow and SNPedia. WikiLeaks began as a MediaWiki-based site, but is no longer a wiki.
+
+A number of alternative wiki encyclopedias to Wikipedia run on MediaWiki, including Citizendium, Metapedia, Scholarpedia and Conservapedia. MediaWiki is also used internally by a large number of companies, including Novell and Intel.[34][35]
+
+Notable usages of MediaWiki within governments include Intellipedia, used by the United States Intelligence Community, Diplopedia, used by the United States Department of State, and milWiki, a part of milSuite used by the United States Department of Defense. United Nations agencies such as the United Nations Development Programme and INSTRAW chose to implement their wikis using MediaWiki, because "this software runs Wikipedia and is therefore guaranteed to be thoroughly tested, will continue to be developed well into the future, and future technicians on these wikis will be more likely to have exposure to MediaWiki than any other wiki software."[36]
+
+The Free Software Foundation uses MediaWiki to implement the LibrePlanet site.[37]
+
+MediaWiki provides a rich core feature set and a mechanism to attach extensions to provide additional functionality.
+
+Due to the strong emphasis on multilingualism in the Wikimedia projects, internationalization and localization has received significant attention by developers. The user interface has been fully or partially translated into more than 300 languages on translatewiki.net,[11] and can be further customized by site administrators (the entire interface is editable through the wiki).
+
+Several extensions, most notably those collected in the MediaWiki Language Extension Bundle, are designed to further enhance the multilingualism and internationalization of MediaWiki.
+
+Installation of MediaWiki requires that the user have administrative privileges on a server running both PHP and a compatible type of SQL database. Some users find that setting up a virtual host is helpful if the majority of one's site runs under a framework (such as Zope or Ruby on Rails) that is largely incompatible with MediaWiki.[38] Cloud hosting can eliminate the need to deploy a new server.[39]
+
+An installation PHP script is accessed via a web browser to initialize the wiki's settings. It prompts the user for a minimal set of required parameters, leaving further changes, such as enabling uploads,[40] adding a site logo,[41] and installing extensions, to be made by modifying configuration settings contained in a file called LocalSettings.php.[42] Some aspects of MediaWiki can be configured through special pages or by editing certain pages; for instance, abuse filters can be configured through a special page,[43] and certain gadgets can be added by creating JavaScript pages in the MediaWiki namespace.[44] The MediaWiki community publishes a comprehensive installation guide.[45]
+
+One of the earliest differences between MediaWiki (and its predecessor, UseModWiki) and other wiki engines was the use of "free links" instead of CamelCase. When MediaWiki was created, it was typical for wikis to require text like "WorldWideWeb" to create a link to a page about the World Wide Web; links in MediaWiki, on the other hand, are created by surrounding words with double square brackets, and any spaces between them are left intact, e.g. [[World Wide Web]]. This change was logical for the purpose of creating an encyclopedia, where accuracy in titles is important.
+
+MediaWiki uses an extensible[46] lightweight wiki markup designed to be easier to use and learn than HTML. Tools exist for converting content such as tables between MediaWiki markup and HTML.[47] Efforts have been made to create a MediaWiki markup spec, but a consensus seems to have been reached that Wikicode requires context-sensitive grammar rules.[48][49] The following side-by-side comparison illustrates the differences between wiki markup and HTML:
+
+"Take some more tea," the March Hare said to Alice, very earnestly.
+
+"I've had nothing yet," Alice replied in an offended tone: "so I can't take more."
+
+"You mean you can't take less," said the Hatter: "it's very easy to take more than nothing."
+
+(Quotation above from Alice's Adventures in Wonderland by Lewis Carroll)
+
+MediaWiki's default page-editing tools have been described as somewhat challenging to learn.[50] A survey of students assigned to use a MediaWiki-based wiki found that when they were asked an open question about main problems with the wiki, 24% cited technical problems with formatting, e.g. "Couldn't figure out how to get an image in. Can't figure out how to show a link with words; it inserts a number."[51]
+
+To make editing long pages easier, MediaWiki allows the editing of a subsection of a page (as identified by its header). A registered user can also indicate whether or not an edit is minor. Correcting spelling, grammar or punctuation are examples of minor edits, whereas adding paragraphs of new text is an example of a non-minor edit.
+
+Sometimes while one user is editing, a second user saves an edit to the same part of the page. Then, when the first user attempts to save the page, an edit conflict occurs. The second user is then given an opportunity to merge their content into the page as it now exists following the first user's page save.
+
+MediaWiki's user interface has been localized in many different languages. A language for the wiki content itself can also be set, to be sent in the "Content-Language" HTTP header and "lang" HTML attribute.
+
+MediaWiki has an extensible web API (application programming interface) that provides direct, high-level access to the data contained in the MediaWiki databases. Client programs can use the API to log in, get data, and post changes. The API supports thin web-based JavaScript clients and end-user applications (such as vandal-fighting tools). The API can be accessed by the backend of another web site.[52] An extensive Python bot library, Pywikibot,[53] and a popular semi-automated tool called AutoWikiBrowser, also interface with the API.[54] The API is accessed via URLs such as http://en.wikipedia.org/w/api.php?action=query&list=recentchanges. In this case, the query would be asking Wikipedia for information relating to the last 10 edits to the site. One of the perceived advantages of the API is its language independence; it listens for HTTP connections from clients and can send a response in a variety of formats, such as XML, serialized PHP, or JSON.[55] Client code has been developed to provide layers of abstraction to the API.[56]
+
+MediaWiki supports rich content generated through specialized syntax. For example, the software comes with optional support for rendering mathematical formulas using LaTeX and a special parser written in OCaml. Similar functionality for other content, ranging from graphical timelines over mathematical plotting and musical scores to Egyptian hieroglyphs, is available via extensions.
+
+The software has become more powerful at dealing with a wide variety of uploaded media files. Its richest functionality is in the area of images, where image galleries and thumbnails can be generated with relative ease. There is also support for Exif metadata. The use of MediaWiki to operate the Wikimedia Commons, one of the largest free content media archives, has driven the need for further functionality in this area.
+
+Because any WYSIWYG editor would have to know wikitext grammar, and no full grammar for wikitext exists, MediaWiki currently provides no native WYSIWYG support.[57] It does come with a customizable graphical toolbar for simplifying the process of learning the wiki syntax.[58] Various extensions exist for handling WYSIWYG editing to different degrees.[59]
+
+Among the features of MediaWiki to assist in tracking edits is a Recent Changes feature that provides a list of recent edits to the wiki. This list contains basic information about those edits such as the editing user, the edit summary, the page edited, as well as any tags (e.g. "possible malware link")[60] added by customizable abuse filters and other extensions to aid in combating unhelpful edits.[61] On more active wikis, so many edits occur that it is hard to track Recent Changes manually. Anti-vandal software, including user-assisted tools[62] are sometimes employed on such wikis to process Recent Changes items. Server load can be reduced by sending a continuous feed of Recent Changes to an IRC channel that these tools can monitor, eliminating their need to send requests for a refreshed Recent Changes feed to the API.[63][64]
+
+Another important tool is watchlisting. Each logged-in user has a watchlist to which the user can add whatever pages he or she wishes. When an edit is made to one of those pages, a summary of that edit appears on the watchlist the next time it is refreshed.[65] As with the recent changes page, recent edits that appear on the watchlist contain clickable links for easy review of the article history and specific changes made.
+
+There is also capability to review all edits made by any particular user. In this way, if an edit is identified as problematic, it is possible to check the user's other edits for issues.
+
+MediaWiki allows one to link to specific versions of articles. This has been useful to the scientific community, in that expert peer reviewers could analyse articles, improve them and provide links to the trusted version of that article.[66]
+
+Navigation through the wiki is largely through internal wikilinks. MediaWiki's wikilinks implement page existence detection, in which a link is colored blue if the target page exists on the local wiki and red if it does not. If a user clicks on a red link, they are prompted to create an article with that title. Page existence detection makes it practical for users to create "wikified" articles — that is, articles containing links to other pertinent subjects — without those other articles being yet in existence.
+
+Interwiki links function much the same way as namespaces. A set of interwiki prefixes can be configured to cause, for instance, a page title of wikiquote:Jimbo Wales to direct the user to the Jimbo Wales article on Wikiquote.[67] Unlike internal wikilinks, interwiki links lack page existence detection functionality, and accordingly there is no way to tell whether a blue interwiki link is broken or not.
+
+Page tabs are displayed at the top of pages. These tabs allow users to perform actions or view pages that are related to the current page. The available default actions include viewing, editing, and discussing the current page. The specific tabs displayed depend on whether or not the user is logged into the wiki and whether the user has sysop privileges on the wiki. For instance, the ability to move a page or add it to one's watchlist is usually restricted to logged-in users. The site administrator can add or remove tabs by using JavaScript or installing extensions.[68]
+
+Each page has an associated history page from which the user can access every version of the page that has ever existed and generate diffs between two versions of his choice. Users' contributions are displayed not only here, but also via a "user contributions" option on a sidebar. Carl Challborn & Teresa Reimann note that "While this feature may be a slight deviation from the collaborative, 'ego-less' spirit of wiki purists, it can be
+very useful for educators who need to assess the contribution and participation of individual student users."[69]
+
+MediaWiki provides many features beyond hyperlinks for structuring content. One of the earliest such features is namespaces. One of Wikipedia's earliest problems had been the separation of encyclopedic content from pages pertaining to maintenance and communal discussion, as well as personal pages about encyclopedia editors. Namespaces are prefixes before a page title (such as "User:" or "Talk:") that serve as descriptors for the page's purpose and allow multiple pages with different functions to exist under the same title. For instance, a page titled "[[The Terminator]]", in the default namespace, could describe the 1984 movie starring Arnold Schwarzenegger, while a page titled "[[User:The Terminator]]" could be a profile describing a user who chooses this name as a pseudonym. More commonly, each namespace has an associated "Talk:" namespace, which can be used to discuss its contents, such as "User talk:" or "Template talk:". The purpose of having discussion pages is to allow content to be separated from discussion surrounding the content.[70][71]
+
+Namespaces can be viewed as folders that separate different basic types of information or functionality. Custom namespaces can be added by the site administrators. There are 16 namespaces by default for content, with 2 "pseudo-namespaces" used for dynamically generated "Special:" pages and links to media files. Each namespace on MediaWiki is numbered: content page namespaces have even numbers and their associated talk page namespaces have odd numbers.[72]
+
+Users can create new categories and add pages and files to those categories by appending one or more category tags to the content text. Adding these tags creates links at the bottom of the page that take the reader to the list of all pages in that category, making it easy to browse related articles.[73] The use of categorization to organize content has been described as a combination of:
+
+In addition to namespaces, content can be ordered using subpages. This simple feature provides automatic breadcrumbs of the pattern [[Page title/Subpage title]] from the page after the slash (in this case, "Subpage title") to the page before the slash (in this case, "Page title").
+
+If the feature is enabled, users can customize their stylesheets and configure client-side JavaScript to be executed with every pageview. On Wikipedia, this has led to a large number of additional tools and helpers developed through the wiki and shared among users. For instance, navigation popups is a custom JavaScript tool that shows previews of articles when the user hovers over links, and also provides shortcuts for common maintenance tasks.[75]
+
+The entire MediaWiki user interface can be edited through the wiki itself by users with the necessary permissions (typically called "administrators"). This is done through a special namespace with the prefix "MediaWiki:", where each page title identifies a particular user interface message. Using an extension,[76] it is also possible for a user to create personal scripts, and to choose whether certain sitewide scripts should apply to them by toggling the appropriate options in the user preferences page.
+
+The "MediaWiki:" namespace was also originally used for creating custom text blocks that could then be dynamically loaded into other pages using a special syntax. This content was later moved into its own namespace, "Template:".
+
+Templates are text blocks that can be dynamically loaded inside another page whenever that page is requested. The template is a special link in double curly brackets (for example "{{Disputed|date=October 2018}}"), which calls the template (in this case located at Template:Disputed) to load in place of the template call.
+
+Templates are structured documents containing attribute–value pairs. They are defined with parameters, to which are assigned values when transcluded on an article page. The name of the parameter is delimited from the value by an equals sign. A class of templates known as infoboxes is used on Wikipedia to collect and present a subset of information about its subject, usually on the top (mobile view) or top right-hand corner (desktop view) of the document.
+
+A related method, called template substitution (called by adding subst: at the beginning of a template link) inserts (like a copy and paste operation) the contents of the template into the target page, instead of loading the template contents dynamically whenever the page is loaded. This can lead to inconsistency when using templates, but may be useful in certain cases, and in most cases requires fewer server resources (the actual amount of savings can vary depending on wiki configuration and the complexity of the template).
+
+Templates have found many different uses. Templates enable users to create complex table layouts that are used consistently across multiple pages, and where only the content of the tables gets inserted using template parameters. Templates are often used to identify problems with a Wikipedia article by putting a template in the article. This template then outputs a graphical box stating that the article content is disputed or in need of some other attention, and also categorize it so that articles of this nature can be located. Templates are also used on user pages to send users standard messages welcoming them to the site,[77] giving them awards for outstanding contributions,[78][79] warning them when their behavior is considered inappropriate,[80] notifying them when they are blocked from editing,[81] and so on.
+
+MediaWiki offers flexibility in creating and defining user groups. For instance, it would be possible to create an arbitrary "ninja" group that can block users and delete pages, and whose edits are hidden by default in the recent changes log. It is also possible to set up a group of "autoconfirmed" users that one becomes a member of after making a certain number of edits and waiting a certain number of days.[82] Some groups that are enabled by default are bureaucrats and sysops. Bureaucrats have power to change other users' rights. Sysops have power over page protection and deletion and the blocking of users from editing. MediaWiki's available controls on editing rights have been deemed sufficient for publishing and maintaining important documents such as a manual of standard operating procedures in a hospital.[83]
+
+When a page consists only of useless content, there are several ways to remove that content. The simplest way, available to all users, is simply to blank the page. However, this interferes with page existence detection, unless an extension is installed to treat blanked pages as though they were nonexistent.[84] Blanking also leaves the content accessible through the history page, an outcome that, while potentially increasing transparency by allowing non-sysops to easily review the content removal decision for appropriateness, might be unacceptable or even unlawful[85] in some cases. Another option is for a sysop to delete the page, and thereby prevent it from being viewed by non-sysops. Another level of deletion, called RevisionDelete, can be used by a group (e.g. "Oversighters") to prevent a page from being viewed by non-members of that group.[86] It is also possible, using certain extensions, to remove content from being viewed through any of the normal channels on the wiki,[87] or even to completely delete revisions from the database.[88]
+
+MediaWiki comes with a basic set of features related to restricting access, but its original and ongoing design is driven by functions that largely relate to content, not content segregation. As a result, with minimal exceptions (related to specific tools and their related "Special" pages), page access control has never been a high priority in core development and developers have stated that users requiring secure user access and authorization controls should not rely on MediaWiki, since it was never designed for these kinds of situations. For instance, it is extremely difficult to create a wiki where only certain users can read and access some pages.[89] Here, wiki engines like Foswiki, MoinMoin and Confluence provide more flexibility by supporting advanced security mechanisms like access control lists.
+
+The MediaWiki codebase contains various "hooks" using callback functions to add additional PHP code in an extensible way. This allows developers to write extensions without necessarily needing to modify the core or having to submit their code for review. Installing an extension typically consists of adding a line to the configuration file, though in some cases additional changes such as database updates or core patches are required.
+
+Five main extension points were created to allow developers to add features and functionalities to MediaWiki. Hooks are run every time a certain event happens; for instance, the ArticleSaveComplete hook occurs after a save article request has been processed.[90] This can be used, for example, by an extension that notifies selected users whenever a page edit occurs on the wiki from new or anonymous users.[91] New tags can be created to process data with opening and closing tags (<newtag>...</newtag>).[92] Parser functions can be used to create a new command ({{#if:...|...|...}}).[93] New special pages can be created to perform a specific function. These pages are dynamically generated. For example, a special page might show all pages that have one or more links to an external site or it might create a form providing user submitted feedback.[94] Skins allow users to customize the look and feel of MediaWiki.[95] A minor extension point allows the use of Amazon S3 to host image files.[96]
+
+MediaWiki can be made more advanced and useful for various purposes through its extensions. These extensions vary greatly in complexity.
+
+The Wikimedia Foundation operates a Git server where many extensions host their repository. Most of them also have a documentation page on the MediaWiki website.
+
+MediaWiki code review was itself historically facilitated through a MediaWiki extension.[97] As of March 2012, it has been done through Gerrit.
+
+Since version 1.16, MediaWiki uses the jQuery library.[98]
+
+Among the most popular extensions is a parser function extension, ParserFunctions, which allows different content to be rendered based on the result of conditional statements.[99] These conditional statements can perform functions such as evaluating whether a parameter is empty, comparing strings, evaluating mathematical expressions, and returning one of two values depending on whether a page exists. It was designed as a replacement for a notoriously inefficient template called {{Qif}}.[100] Schindler recounts the history of the ParserFunctions extension as follows:[31]
+
+In 2006 some Wikipedians discovered that through an intricate and complicated interplay of templating features and CSS they could create conditional wiki text, i.e. text that was displayed if a template parameter had a specific value. This included repeated calls of templates within templates, which bogged down the performance of the whole system. The developers faced the choice of either disallowing the spreading of an obviously desired feature by detecting such usage and explicitly disallowing it within the software, or offer an efficient alternative. The latter was done by Tim Starling, who announced the introduction of parser functions, wiki text that calls functions implemented in the underlying software.
+At first, only conditional text and the computation of simple mathematical expressions was implemented, but this already increased the possibilities for wiki editors enormously. With time further parser functions were introduced, finally leading to a framework that allowed the simple writing of extension function to add arbitrary functionalities, like e.g. geo-coding services or widgets. This time the developers were clearly reacting to the demand of the community, being forced either to fight the solution of the issue that the community had (i.e. conditional text), or offer an improved technical implementation to replace the previous practice and achieve an overall better performance.
+
+Another parser functions extension, StringFunctions, was developed to allow evaluation of string length, string position, and so on. Wikimedia communities, having created awkward workarounds to accomplish the same functionality,[101] clamored for it to be enabled on their projects.[102] Much of its functionality was eventually integrated into the ParserFunctions extension,[103] albeit disabled by default and accompanied by a warning from Tim Starling that enabling string functions would allow users "to implement their own parsers in the ugliest, most inefficient programming language known to man: MediaWiki wikitext with ParserFunctions."[104]
+
+Since 2012 an extension, Scribunto, has existed that allows for the creation of "modules" — wiki pages written in the scripting language Lua — which can then be run within templates and standard wiki pages. Scribunto has been installed on Wikipedia and other Wikimedia sites since 2013, and is used heavily on those sites. Scribunto code runs significantly faster than corresponding wikitext code using ParserFunctions.[105]
+
+Another very popular extension is a citation extension that enables footnotes to be added to pages using inline references.[106] This extension has, however, been criticized for being difficult to use and requiring the user to memorize complex syntax. A gadget called RefToolbar attempts to make it easier to create citations using common templates. MediaWiki has some extensions that are well-suited for academia, such as mathematics extensions[107] and an extension that allows molecules to be rendered in 3D.[108]
+
+A generic Widgets extension exists that allows MediaWiki to integrate with virtually anything. Other examples of extensions that could improve a wiki are category suggestion extensions[109] and extensions for inclusion of Flash Videos,[110] YouTube videos,[111] and RSS feeds.[112] Metavid, a site that archives video footage of the U.S. Senate and House floor proceedings, was created using code extending MediaWiki into the domain of collaborative video authoring.[113]
+
+There are many spambots that search the web for MediaWiki installations and add linkspam to them, despite the fact that MediaWiki uses the nofollow attribute to discourage such attempts at search engine optimization.[114] Part of the problem is that third party republishers, such as mirrors, may not independently implement the nofollow tag on their websites, so marketers can still get PageRank benefit by inserting links into pages when those entries appear on third party websites.[115] Anti-spam extensions have been developed to combat the problem by introducing CAPTCHAs,[116] blacklisting certain URLs,[117] and allowing bulk deletion of pages recently added by a particular user.[118]
+
+MediaWiki comes pre-installed with a standard text-based search. Extensions exist to let MediaWiki use more sophisticated third-party search engines, including Elasticsearch (which since 2014 has been in use on Wikipedia), Lucene[119] and Sphinx.[120]
+
+Various MediaWiki extensions have also been created to allow for more complex, faceted search, on both data entered within the wiki and on metadata such as pages' revision history.[121][122] Semantic MediaWiki is one such extension.[123][124]
+
+MediaWiki can use either the MySQL/MariaDB, PostgreSQL or SQLite relational database management system. There is limited support for Oracle Database and Microsoft SQL Server.[125] A MediaWiki database contains several dozen tables, including a page table that contains page titles, page ids, and other metadata;[126] and a revision table to which is added a new row every time an edit is made, containing the page id, a brief textual summary of the change performed, the user name of the article editor (or its IP address the case of an unregistered user) and a timestamp.[127][128]
+
+In a 4½ year period, the MediaWiki database had 170 schema versions.[129] Possibly the largest schema change was done in MediaWiki 1.5, when the storage of metadata was separated from that of content, to improve performance flexibility. When this upgrade was applied to Wikipedia, the site was locked for editing, and the schema was converted to the new version in about 22 hours. Some software enhancement proposals, such as a proposal to allow sections of articles to be watched via watchlist, have been rejected because the necessary schema changes would have required excessive Wikipedia downtime.[130]
+
+Because it is used to run one of the highest-traffic sites on the Web, Wikipedia, MediaWiki's performance and scalability have been highly optimized.[30] MediaWiki supports Squid, load-balanced database replication, client-side caching, memcached or table-based caching for frequently accessed processing of query results, a simple static file cache, feature-reduced operation, revision compression, and a job queue for database operations. MediaWiki developers have attempted to optimize the software by avoiding expensive algorithms, database queries, etc., caching every result that is expensive and has temporal locality of reference, and focusing on the hot spots in the code through profiling.[131]
+
+MediaWiki code is designed to allow for data to be written to a master database and read from slave databases, although the master can be used for some read operations if the slaves are not yet up to date. Metadata, such as article revision history, article relations (links, categories etc.), user accounts and settings can be stored in core databases and cached; the actual revision text, being more rarely used, can be stored as append-only blobs in external storage.  The software is suitable for the operation of large scale wiki farms such as Wikimedia, which had about 800 wikis as of August 2011. However, MediaWiki comes with no built-in GUI to manage such installations.
+
+Empirical evidence shows most revisions in MediaWiki databases tend to differ only slightly from previous revisions. Therefore, subsequent revisions of an article can be concatenated and then compressed, achieving very high data compression ratios of up to 100x.[131]
+
+For more information on the architecture, such as how it stores wikitext and assembles a page, see External links.
+
+The parser serves as the de facto standard for the MediaWiki syntax, as no formal syntax has been defined. Due to this lack of a formal definition, it has been difficult to create WYSIWYG editors for MediaWiki, although several WYSIWYG extensions do exist, including the popular VisualEditor.
+
+MediaWiki is not designed to be a suitable replacement for dedicated online forum or blogging software,[132] although extensions do exist to allow for both of these.[133][134]
+
+It is common for new MediaWiki users to make certain mistakes, such as forgetting to sign posts with four tildes (~~~~),[135] or manually entering a plaintext signature,[136] due to unfamiliarity with the idiosyncratic particulars involved in communication on MediaWiki discussion pages. On the other hand, the format of these discussion pages has been cited as a strength by one educator, who stated that it provides more fine-grain capabilities for discussion than traditional threaded discussion forums. For example, instead of 'replying' to an entire message, the participant in a discussion can create a hyperlink to a new wiki page on any word from the original page. Discussions are easier to follow since the content is available via hyperlinked wiki page, rather than a series of reply messages on a traditional threaded discussion forum. However, except in few cases, students were not using this capability, possibly because of their familiarity with the traditional linear discussion style and a lack of guidance on how to make the content more 'link-rich'.[137]
+
+MediaWiki by default has little support for the creation of dynamically assembled documents, or pages that aggregate data from other pages. Some research has been done on enabling such features directly within MediaWiki.[138] The Semantic MediaWiki extension provides these features. It is not in use on Wikipedia, but in more than 1,600 other MediaWiki installations.[139] The Wikibase Repository and Wikibase Repository client are however implemented in Wikidata and Wikipedia respectively, and to some extent provides semantic web features, and linking of centrally stored data to infoboxes in various Wikipedia articles.
+
+Upgrading MediaWiki is usually fully automated, requiring no changes to the site content or template programming. Historically troubles have been encountered when upgrading from significantly older versions.[140]
+
+MediaWiki developers have enacted security standards, both for core code and extensions.[141] SQL queries and HTML output are usually done through wrapper functions that handle validation, escaping, filtering for prevention of cross-site scripting and SQL injection.[142]  Many security issues have had to be patched after a MediaWiki version release,[143] and accordingly MediaWiki.org states, "The most important security step you can take is to keep your software up to date" by subscribing to the announcement listserv and installing security updates that are announced.[144]
+
+MediaWiki developers are spread around the world, though with a majority in the United States and Europe. Face-to-face meetings and programming sessions for MediaWiki developers have been held once or several times a year since 2004.[145]
+
+Support for MediaWiki users consists of:
+
+Users of online collaboration software are familiar with MediaWiki's functions and layout due to its noted use on Wikipedia. Compared to other wikis, MediaWiki is also fairly aesthetically pleasing, though simple, and has an easily customized side menu and stylesheet.[149] However, in one assessment in 2006, Confluence was deemed to be a superior product due to its very usable API and ability to better support multiple wikis.[108] Wiki providers Socialtext and JotSpot have/had project management features that MediaWiki lacks.[150]
+
+A study was done at the University of Hong Kong comparing TWiki to MediaWiki. The authors noted that TWiki has been considered as a collaborative tool for development of educational papers and technical projects, whereas MediaWiki's most noted use is on Wikipedia. Although both platforms allow discussion and tracking of progress, TWiki has a "Report" part that MediaWiki lacks. Students perceived MediaWiki as being easier to use and more enjoyable than TWiki. When asked whether they recommended using MediaWiki for knowledge management course group project, 15 out of 16 respondents expressed their preference for MediaWiki giving answers of great certainty, such as "of course", "for sure".[151] TWiki and MediaWiki both have flexible plug-in architecture.[152]
+
+A study that compared students' experience with MediaWiki to that with Google Documents found that students gave the latter a much higher rating on user-friendly layout.[153]

en/3753.html.txt

@@ -0,0 +1,190 @@
+
+
+
+
+MediaWiki is a free and open-source wiki engine. It was developed for use on Wikipedia in 2002, and given the name "MediaWiki" in 2003.[6] It remains in use on Wikipedia and almost all other Wikimedia websites, including Wiktionary, Wikimedia Commons and Wikidata; these sites continue to define a large part of the requirement set for MediaWiki.[7] MediaWiki was originally developed by Magnus Manske and improved by Lee Daniel Crocker.[8][9] Its development has since then been coordinated by the Wikimedia Foundation.
+
+MediaWiki is written in the PHP programming language and stores all text content into a database. The software is optimized to efficiently handle large projects, which can have terabytes of content and hundreds of thousands of hits per second.[7][10] Because Wikipedia is one of the world's largest websites, achieving scalability through multiple layers of caching and database replication has been a major concern for developers. Another major aspect of MediaWiki is its internationalization; its interface is available in more than 300 languages.[11] The software has more than 1,000 configuration settings[12] and more than 1,800 extensions available for enabling various features to be added or changed.[13]
+
+Besides its use on Wikimedia sites, MediaWiki has been used as a knowledge management and content management system on many thousands of websites, public and private, including the websites Fandom, wikiHow and Gamepedia, and major internal installations like Intellipedia and Diplopedia.
+
+MediaWiki is free and open-source software and is distributed under the terms of the GNU General Public License version 2 or any later version. Its documentation, located at www.mediawiki.org, is released under the Creative Commons BY-SA 3.0 license and partly in the public domain.[14] Specifically, the manuals and other content at MediaWiki.org are Creative Commons-licensed, while the set of help pages intended to be freely copied into fresh wiki installations and/or distributed with MediaWiki software is public domain. This was done to eliminate legal issues arising from the help pages being imported into wikis with licenses that are incompatible with the Creative Commons license.[15] MediaWiki development has generally favored the use of open-source media formats.[16]
+
+MediaWiki has an active volunteer community for development and maintenance. Users who have made meaningful contributions to the project by submitting patches are generally, upon request, granted access to commit revisions to the project's Git/Gerrit repository.[17]
+There are also paid programmers who primarily develop projects for the Wikimedia Foundation. MediaWiki developers participate in the Google Summer of Code by facilitating the assignment of mentors to students wishing to work on MediaWiki core and extension projects.[18]
+During the year prior to November 2012, there were about two hundred developers who had committed changes to the MediaWiki core or extensions.[19]
+Major MediaWiki releases are generated approximately every six months by taking snapshots of the development branch, which is kept continuously in a runnable state;[20] minor releases, or point releases, are issued as needed to correct bugs (especially security problems).
+
+MediaWiki also has a public bug tracker, phabricator.wikimedia.org, which runs Phabricator. The site is also used for feature and enhancement requests.
+
+When Wikipedia was launched in January 2001, it ran on the existing wiki software, UseModWiki. UseModWiki is written in the Perl programming language, and stores all wiki pages, in text (.txt) files. This software soon proved to be limiting, in both functionality and performance. In mid-2001, Magnus Manske — a developer and student at the University of Cologne, as well as, a Wikipedia editor — began working on new software that would replace UseModWiki, specifically designed for use by Wikipedia. This software was written in the PHP scripting language, and stored all of its information in a MySQL engine database. The new software was largely developed by August 24, 2001, and a test wiki for it was established shortly thereafter.
+
+The first, full–implementation of this software, was the new Meta Wikipedia on November 9, 2001. There was a desire to have it implemented immediately on the English-language Wikipedia,[21] however, Manske was apprehensive about any potential bugs harming the nascent website during the period of the final exams he had to complete immediately prior to Christmas;[22] this led to the launch on the English-language Wikipedia being delayed until January 25, 2002. The software was then, gradually, deployed on all the Wikipedia language sites of that time. This software was referred to as "the PHP script" and as "phase II", with the name "phase I", retroactively given to the use of UseModWiki.
+
+Increasing usage soon caused load problems to arise again, and soon after, another rewrite of the software began; this time being done by Lee Daniel Crocker, which became known as "phase III". This new software was also written in PHP, with a MySQL back-end, and kept the basic interface of the phase II software, but with the added functionality of a wider scalability. The "phase III" software went live on Wikipedia in July 2002.
+
+The Wikimedia Foundation was announced on June 20, 2003. In July, Wikipedia contributor Daniel Mayer, suggested the name "MediaWiki" for the software, as a play on "Wikimedia".[23] The MediaWiki name, was gradually phased in, beginning in August 2003. The name has frequently caused confusion due to its (intentional) similarity to the "Wikimedia" name (which itself is similar to "Wikipedia").[24]
+
+The product logo was created by Erik Möller, using a flower photograph taken by Florence Nibart-Devouard, and was originally submitted to the logo contest for a new Wikipedia logo, held in from July 20 to August 27, 2003.[25][26] The logo came in 3rd place, and was chosen to represent MediaWiki rather than Wikipedia, with the 2nd place logo being used for the Wikimedia Foundation.[27] The double square brackets ([[ ]]) symbolize the syntax MediaWiki uses for creating hyperlinks to other wiki pages; while the sunflower, represents the: diversity of content on Wikipedia, the constant growth, and also the wildness.[28]
+
+Later, Brion Vibber, the Chief Technical Officer of the Wikimedia Foundation,[29] took up the role of Release Manager, and the most active Developer.[6][30]
+
+Major milestones in MediaWiki's development have included: the categorization system (2004); Parser Functions, (2006); Flagged Revisions, (2008);[31] the "ResourceLoader", a delivery system for CSS and JavaScript (2011);[32] and the VisualEditor, a "what you see is what you get" (WYSIWYG) editing platform (2013).[33]
+
+The first version of MediaWiki, 1.1, was released in December 2003.
+
+MediaWiki's most famous use has been in Wikipedia and, to a lesser degree, the Wikimedia Foundation's other projects. Fandom, a wiki hosting service formerly known as Wikia, runs on MediaWiki. Other public wikis that run on MediaWiki include wikiHow and SNPedia. WikiLeaks began as a MediaWiki-based site, but is no longer a wiki.
+
+A number of alternative wiki encyclopedias to Wikipedia run on MediaWiki, including Citizendium, Metapedia, Scholarpedia and Conservapedia. MediaWiki is also used internally by a large number of companies, including Novell and Intel.[34][35]
+
+Notable usages of MediaWiki within governments include Intellipedia, used by the United States Intelligence Community, Diplopedia, used by the United States Department of State, and milWiki, a part of milSuite used by the United States Department of Defense. United Nations agencies such as the United Nations Development Programme and INSTRAW chose to implement their wikis using MediaWiki, because "this software runs Wikipedia and is therefore guaranteed to be thoroughly tested, will continue to be developed well into the future, and future technicians on these wikis will be more likely to have exposure to MediaWiki than any other wiki software."[36]
+
+The Free Software Foundation uses MediaWiki to implement the LibrePlanet site.[37]
+
+MediaWiki provides a rich core feature set and a mechanism to attach extensions to provide additional functionality.
+
+Due to the strong emphasis on multilingualism in the Wikimedia projects, internationalization and localization has received significant attention by developers. The user interface has been fully or partially translated into more than 300 languages on translatewiki.net,[11] and can be further customized by site administrators (the entire interface is editable through the wiki).
+
+Several extensions, most notably those collected in the MediaWiki Language Extension Bundle, are designed to further enhance the multilingualism and internationalization of MediaWiki.
+
+Installation of MediaWiki requires that the user have administrative privileges on a server running both PHP and a compatible type of SQL database. Some users find that setting up a virtual host is helpful if the majority of one's site runs under a framework (such as Zope or Ruby on Rails) that is largely incompatible with MediaWiki.[38] Cloud hosting can eliminate the need to deploy a new server.[39]
+
+An installation PHP script is accessed via a web browser to initialize the wiki's settings. It prompts the user for a minimal set of required parameters, leaving further changes, such as enabling uploads,[40] adding a site logo,[41] and installing extensions, to be made by modifying configuration settings contained in a file called LocalSettings.php.[42] Some aspects of MediaWiki can be configured through special pages or by editing certain pages; for instance, abuse filters can be configured through a special page,[43] and certain gadgets can be added by creating JavaScript pages in the MediaWiki namespace.[44] The MediaWiki community publishes a comprehensive installation guide.[45]
+
+One of the earliest differences between MediaWiki (and its predecessor, UseModWiki) and other wiki engines was the use of "free links" instead of CamelCase. When MediaWiki was created, it was typical for wikis to require text like "WorldWideWeb" to create a link to a page about the World Wide Web; links in MediaWiki, on the other hand, are created by surrounding words with double square brackets, and any spaces between them are left intact, e.g. [[World Wide Web]]. This change was logical for the purpose of creating an encyclopedia, where accuracy in titles is important.
+
+MediaWiki uses an extensible[46] lightweight wiki markup designed to be easier to use and learn than HTML. Tools exist for converting content such as tables between MediaWiki markup and HTML.[47] Efforts have been made to create a MediaWiki markup spec, but a consensus seems to have been reached that Wikicode requires context-sensitive grammar rules.[48][49] The following side-by-side comparison illustrates the differences between wiki markup and HTML:
+
+"Take some more tea," the March Hare said to Alice, very earnestly.
+
+"I've had nothing yet," Alice replied in an offended tone: "so I can't take more."
+
+"You mean you can't take less," said the Hatter: "it's very easy to take more than nothing."
+
+(Quotation above from Alice's Adventures in Wonderland by Lewis Carroll)
+
+MediaWiki's default page-editing tools have been described as somewhat challenging to learn.[50] A survey of students assigned to use a MediaWiki-based wiki found that when they were asked an open question about main problems with the wiki, 24% cited technical problems with formatting, e.g. "Couldn't figure out how to get an image in. Can't figure out how to show a link with words; it inserts a number."[51]
+
+To make editing long pages easier, MediaWiki allows the editing of a subsection of a page (as identified by its header). A registered user can also indicate whether or not an edit is minor. Correcting spelling, grammar or punctuation are examples of minor edits, whereas adding paragraphs of new text is an example of a non-minor edit.
+
+Sometimes while one user is editing, a second user saves an edit to the same part of the page. Then, when the first user attempts to save the page, an edit conflict occurs. The second user is then given an opportunity to merge their content into the page as it now exists following the first user's page save.
+
+MediaWiki's user interface has been localized in many different languages. A language for the wiki content itself can also be set, to be sent in the "Content-Language" HTTP header and "lang" HTML attribute.
+
+MediaWiki has an extensible web API (application programming interface) that provides direct, high-level access to the data contained in the MediaWiki databases. Client programs can use the API to log in, get data, and post changes. The API supports thin web-based JavaScript clients and end-user applications (such as vandal-fighting tools). The API can be accessed by the backend of another web site.[52] An extensive Python bot library, Pywikibot,[53] and a popular semi-automated tool called AutoWikiBrowser, also interface with the API.[54] The API is accessed via URLs such as http://en.wikipedia.org/w/api.php?action=query&list=recentchanges. In this case, the query would be asking Wikipedia for information relating to the last 10 edits to the site. One of the perceived advantages of the API is its language independence; it listens for HTTP connections from clients and can send a response in a variety of formats, such as XML, serialized PHP, or JSON.[55] Client code has been developed to provide layers of abstraction to the API.[56]
+
+MediaWiki supports rich content generated through specialized syntax. For example, the software comes with optional support for rendering mathematical formulas using LaTeX and a special parser written in OCaml. Similar functionality for other content, ranging from graphical timelines over mathematical plotting and musical scores to Egyptian hieroglyphs, is available via extensions.
+
+The software has become more powerful at dealing with a wide variety of uploaded media files. Its richest functionality is in the area of images, where image galleries and thumbnails can be generated with relative ease. There is also support for Exif metadata. The use of MediaWiki to operate the Wikimedia Commons, one of the largest free content media archives, has driven the need for further functionality in this area.
+
+Because any WYSIWYG editor would have to know wikitext grammar, and no full grammar for wikitext exists, MediaWiki currently provides no native WYSIWYG support.[57] It does come with a customizable graphical toolbar for simplifying the process of learning the wiki syntax.[58] Various extensions exist for handling WYSIWYG editing to different degrees.[59]
+
+Among the features of MediaWiki to assist in tracking edits is a Recent Changes feature that provides a list of recent edits to the wiki. This list contains basic information about those edits such as the editing user, the edit summary, the page edited, as well as any tags (e.g. "possible malware link")[60] added by customizable abuse filters and other extensions to aid in combating unhelpful edits.[61] On more active wikis, so many edits occur that it is hard to track Recent Changes manually. Anti-vandal software, including user-assisted tools[62] are sometimes employed on such wikis to process Recent Changes items. Server load can be reduced by sending a continuous feed of Recent Changes to an IRC channel that these tools can monitor, eliminating their need to send requests for a refreshed Recent Changes feed to the API.[63][64]
+
+Another important tool is watchlisting. Each logged-in user has a watchlist to which the user can add whatever pages he or she wishes. When an edit is made to one of those pages, a summary of that edit appears on the watchlist the next time it is refreshed.[65] As with the recent changes page, recent edits that appear on the watchlist contain clickable links for easy review of the article history and specific changes made.
+
+There is also capability to review all edits made by any particular user. In this way, if an edit is identified as problematic, it is possible to check the user's other edits for issues.
+
+MediaWiki allows one to link to specific versions of articles. This has been useful to the scientific community, in that expert peer reviewers could analyse articles, improve them and provide links to the trusted version of that article.[66]
+
+Navigation through the wiki is largely through internal wikilinks. MediaWiki's wikilinks implement page existence detection, in which a link is colored blue if the target page exists on the local wiki and red if it does not. If a user clicks on a red link, they are prompted to create an article with that title. Page existence detection makes it practical for users to create "wikified" articles — that is, articles containing links to other pertinent subjects — without those other articles being yet in existence.
+
+Interwiki links function much the same way as namespaces. A set of interwiki prefixes can be configured to cause, for instance, a page title of wikiquote:Jimbo Wales to direct the user to the Jimbo Wales article on Wikiquote.[67] Unlike internal wikilinks, interwiki links lack page existence detection functionality, and accordingly there is no way to tell whether a blue interwiki link is broken or not.
+
+Page tabs are displayed at the top of pages. These tabs allow users to perform actions or view pages that are related to the current page. The available default actions include viewing, editing, and discussing the current page. The specific tabs displayed depend on whether or not the user is logged into the wiki and whether the user has sysop privileges on the wiki. For instance, the ability to move a page or add it to one's watchlist is usually restricted to logged-in users. The site administrator can add or remove tabs by using JavaScript or installing extensions.[68]
+
+Each page has an associated history page from which the user can access every version of the page that has ever existed and generate diffs between two versions of his choice. Users' contributions are displayed not only here, but also via a "user contributions" option on a sidebar. Carl Challborn & Teresa Reimann note that "While this feature may be a slight deviation from the collaborative, 'ego-less' spirit of wiki purists, it can be
+very useful for educators who need to assess the contribution and participation of individual student users."[69]
+
+MediaWiki provides many features beyond hyperlinks for structuring content. One of the earliest such features is namespaces. One of Wikipedia's earliest problems had been the separation of encyclopedic content from pages pertaining to maintenance and communal discussion, as well as personal pages about encyclopedia editors. Namespaces are prefixes before a page title (such as "User:" or "Talk:") that serve as descriptors for the page's purpose and allow multiple pages with different functions to exist under the same title. For instance, a page titled "[[The Terminator]]", in the default namespace, could describe the 1984 movie starring Arnold Schwarzenegger, while a page titled "[[User:The Terminator]]" could be a profile describing a user who chooses this name as a pseudonym. More commonly, each namespace has an associated "Talk:" namespace, which can be used to discuss its contents, such as "User talk:" or "Template talk:". The purpose of having discussion pages is to allow content to be separated from discussion surrounding the content.[70][71]
+
+Namespaces can be viewed as folders that separate different basic types of information or functionality. Custom namespaces can be added by the site administrators. There are 16 namespaces by default for content, with 2 "pseudo-namespaces" used for dynamically generated "Special:" pages and links to media files. Each namespace on MediaWiki is numbered: content page namespaces have even numbers and their associated talk page namespaces have odd numbers.[72]
+
+Users can create new categories and add pages and files to those categories by appending one or more category tags to the content text. Adding these tags creates links at the bottom of the page that take the reader to the list of all pages in that category, making it easy to browse related articles.[73] The use of categorization to organize content has been described as a combination of:
+
+In addition to namespaces, content can be ordered using subpages. This simple feature provides automatic breadcrumbs of the pattern [[Page title/Subpage title]] from the page after the slash (in this case, "Subpage title") to the page before the slash (in this case, "Page title").
+
+If the feature is enabled, users can customize their stylesheets and configure client-side JavaScript to be executed with every pageview. On Wikipedia, this has led to a large number of additional tools and helpers developed through the wiki and shared among users. For instance, navigation popups is a custom JavaScript tool that shows previews of articles when the user hovers over links, and also provides shortcuts for common maintenance tasks.[75]
+
+The entire MediaWiki user interface can be edited through the wiki itself by users with the necessary permissions (typically called "administrators"). This is done through a special namespace with the prefix "MediaWiki:", where each page title identifies a particular user interface message. Using an extension,[76] it is also possible for a user to create personal scripts, and to choose whether certain sitewide scripts should apply to them by toggling the appropriate options in the user preferences page.
+
+The "MediaWiki:" namespace was also originally used for creating custom text blocks that could then be dynamically loaded into other pages using a special syntax. This content was later moved into its own namespace, "Template:".
+
+Templates are text blocks that can be dynamically loaded inside another page whenever that page is requested. The template is a special link in double curly brackets (for example "{{Disputed|date=October 2018}}"), which calls the template (in this case located at Template:Disputed) to load in place of the template call.
+
+Templates are structured documents containing attribute–value pairs. They are defined with parameters, to which are assigned values when transcluded on an article page. The name of the parameter is delimited from the value by an equals sign. A class of templates known as infoboxes is used on Wikipedia to collect and present a subset of information about its subject, usually on the top (mobile view) or top right-hand corner (desktop view) of the document.
+
+A related method, called template substitution (called by adding subst: at the beginning of a template link) inserts (like a copy and paste operation) the contents of the template into the target page, instead of loading the template contents dynamically whenever the page is loaded. This can lead to inconsistency when using templates, but may be useful in certain cases, and in most cases requires fewer server resources (the actual amount of savings can vary depending on wiki configuration and the complexity of the template).
+
+Templates have found many different uses. Templates enable users to create complex table layouts that are used consistently across multiple pages, and where only the content of the tables gets inserted using template parameters. Templates are often used to identify problems with a Wikipedia article by putting a template in the article. This template then outputs a graphical box stating that the article content is disputed or in need of some other attention, and also categorize it so that articles of this nature can be located. Templates are also used on user pages to send users standard messages welcoming them to the site,[77] giving them awards for outstanding contributions,[78][79] warning them when their behavior is considered inappropriate,[80] notifying them when they are blocked from editing,[81] and so on.
+
+MediaWiki offers flexibility in creating and defining user groups. For instance, it would be possible to create an arbitrary "ninja" group that can block users and delete pages, and whose edits are hidden by default in the recent changes log. It is also possible to set up a group of "autoconfirmed" users that one becomes a member of after making a certain number of edits and waiting a certain number of days.[82] Some groups that are enabled by default are bureaucrats and sysops. Bureaucrats have power to change other users' rights. Sysops have power over page protection and deletion and the blocking of users from editing. MediaWiki's available controls on editing rights have been deemed sufficient for publishing and maintaining important documents such as a manual of standard operating procedures in a hospital.[83]
+
+When a page consists only of useless content, there are several ways to remove that content. The simplest way, available to all users, is simply to blank the page. However, this interferes with page existence detection, unless an extension is installed to treat blanked pages as though they were nonexistent.[84] Blanking also leaves the content accessible through the history page, an outcome that, while potentially increasing transparency by allowing non-sysops to easily review the content removal decision for appropriateness, might be unacceptable or even unlawful[85] in some cases. Another option is for a sysop to delete the page, and thereby prevent it from being viewed by non-sysops. Another level of deletion, called RevisionDelete, can be used by a group (e.g. "Oversighters") to prevent a page from being viewed by non-members of that group.[86] It is also possible, using certain extensions, to remove content from being viewed through any of the normal channels on the wiki,[87] or even to completely delete revisions from the database.[88]
+
+MediaWiki comes with a basic set of features related to restricting access, but its original and ongoing design is driven by functions that largely relate to content, not content segregation. As a result, with minimal exceptions (related to specific tools and their related "Special" pages), page access control has never been a high priority in core development and developers have stated that users requiring secure user access and authorization controls should not rely on MediaWiki, since it was never designed for these kinds of situations. For instance, it is extremely difficult to create a wiki where only certain users can read and access some pages.[89] Here, wiki engines like Foswiki, MoinMoin and Confluence provide more flexibility by supporting advanced security mechanisms like access control lists.
+
+The MediaWiki codebase contains various "hooks" using callback functions to add additional PHP code in an extensible way. This allows developers to write extensions without necessarily needing to modify the core or having to submit their code for review. Installing an extension typically consists of adding a line to the configuration file, though in some cases additional changes such as database updates or core patches are required.
+
+Five main extension points were created to allow developers to add features and functionalities to MediaWiki. Hooks are run every time a certain event happens; for instance, the ArticleSaveComplete hook occurs after a save article request has been processed.[90] This can be used, for example, by an extension that notifies selected users whenever a page edit occurs on the wiki from new or anonymous users.[91] New tags can be created to process data with opening and closing tags (<newtag>...</newtag>).[92] Parser functions can be used to create a new command ({{#if:...|...|...}}).[93] New special pages can be created to perform a specific function. These pages are dynamically generated. For example, a special page might show all pages that have one or more links to an external site or it might create a form providing user submitted feedback.[94] Skins allow users to customize the look and feel of MediaWiki.[95] A minor extension point allows the use of Amazon S3 to host image files.[96]
+
+MediaWiki can be made more advanced and useful for various purposes through its extensions. These extensions vary greatly in complexity.
+
+The Wikimedia Foundation operates a Git server where many extensions host their repository. Most of them also have a documentation page on the MediaWiki website.
+
+MediaWiki code review was itself historically facilitated through a MediaWiki extension.[97] As of March 2012, it has been done through Gerrit.
+
+Since version 1.16, MediaWiki uses the jQuery library.[98]
+
+Among the most popular extensions is a parser function extension, ParserFunctions, which allows different content to be rendered based on the result of conditional statements.[99] These conditional statements can perform functions such as evaluating whether a parameter is empty, comparing strings, evaluating mathematical expressions, and returning one of two values depending on whether a page exists. It was designed as a replacement for a notoriously inefficient template called {{Qif}}.[100] Schindler recounts the history of the ParserFunctions extension as follows:[31]
+
+In 2006 some Wikipedians discovered that through an intricate and complicated interplay of templating features and CSS they could create conditional wiki text, i.e. text that was displayed if a template parameter had a specific value. This included repeated calls of templates within templates, which bogged down the performance of the whole system. The developers faced the choice of either disallowing the spreading of an obviously desired feature by detecting such usage and explicitly disallowing it within the software, or offer an efficient alternative. The latter was done by Tim Starling, who announced the introduction of parser functions, wiki text that calls functions implemented in the underlying software.
+At first, only conditional text and the computation of simple mathematical expressions was implemented, but this already increased the possibilities for wiki editors enormously. With time further parser functions were introduced, finally leading to a framework that allowed the simple writing of extension function to add arbitrary functionalities, like e.g. geo-coding services or widgets. This time the developers were clearly reacting to the demand of the community, being forced either to fight the solution of the issue that the community had (i.e. conditional text), or offer an improved technical implementation to replace the previous practice and achieve an overall better performance.
+
+Another parser functions extension, StringFunctions, was developed to allow evaluation of string length, string position, and so on. Wikimedia communities, having created awkward workarounds to accomplish the same functionality,[101] clamored for it to be enabled on their projects.[102] Much of its functionality was eventually integrated into the ParserFunctions extension,[103] albeit disabled by default and accompanied by a warning from Tim Starling that enabling string functions would allow users "to implement their own parsers in the ugliest, most inefficient programming language known to man: MediaWiki wikitext with ParserFunctions."[104]
+
+Since 2012 an extension, Scribunto, has existed that allows for the creation of "modules" — wiki pages written in the scripting language Lua — which can then be run within templates and standard wiki pages. Scribunto has been installed on Wikipedia and other Wikimedia sites since 2013, and is used heavily on those sites. Scribunto code runs significantly faster than corresponding wikitext code using ParserFunctions.[105]
+
+Another very popular extension is a citation extension that enables footnotes to be added to pages using inline references.[106] This extension has, however, been criticized for being difficult to use and requiring the user to memorize complex syntax. A gadget called RefToolbar attempts to make it easier to create citations using common templates. MediaWiki has some extensions that are well-suited for academia, such as mathematics extensions[107] and an extension that allows molecules to be rendered in 3D.[108]
+
+A generic Widgets extension exists that allows MediaWiki to integrate with virtually anything. Other examples of extensions that could improve a wiki are category suggestion extensions[109] and extensions for inclusion of Flash Videos,[110] YouTube videos,[111] and RSS feeds.[112] Metavid, a site that archives video footage of the U.S. Senate and House floor proceedings, was created using code extending MediaWiki into the domain of collaborative video authoring.[113]
+
+There are many spambots that search the web for MediaWiki installations and add linkspam to them, despite the fact that MediaWiki uses the nofollow attribute to discourage such attempts at search engine optimization.[114] Part of the problem is that third party republishers, such as mirrors, may not independently implement the nofollow tag on their websites, so marketers can still get PageRank benefit by inserting links into pages when those entries appear on third party websites.[115] Anti-spam extensions have been developed to combat the problem by introducing CAPTCHAs,[116] blacklisting certain URLs,[117] and allowing bulk deletion of pages recently added by a particular user.[118]
+
+MediaWiki comes pre-installed with a standard text-based search. Extensions exist to let MediaWiki use more sophisticated third-party search engines, including Elasticsearch (which since 2014 has been in use on Wikipedia), Lucene[119] and Sphinx.[120]
+
+Various MediaWiki extensions have also been created to allow for more complex, faceted search, on both data entered within the wiki and on metadata such as pages' revision history.[121][122] Semantic MediaWiki is one such extension.[123][124]
+
+MediaWiki can use either the MySQL/MariaDB, PostgreSQL or SQLite relational database management system. There is limited support for Oracle Database and Microsoft SQL Server.[125] A MediaWiki database contains several dozen tables, including a page table that contains page titles, page ids, and other metadata;[126] and a revision table to which is added a new row every time an edit is made, containing the page id, a brief textual summary of the change performed, the user name of the article editor (or its IP address the case of an unregistered user) and a timestamp.[127][128]
+
+In a 4½ year period, the MediaWiki database had 170 schema versions.[129] Possibly the largest schema change was done in MediaWiki 1.5, when the storage of metadata was separated from that of content, to improve performance flexibility. When this upgrade was applied to Wikipedia, the site was locked for editing, and the schema was converted to the new version in about 22 hours. Some software enhancement proposals, such as a proposal to allow sections of articles to be watched via watchlist, have been rejected because the necessary schema changes would have required excessive Wikipedia downtime.[130]
+
+Because it is used to run one of the highest-traffic sites on the Web, Wikipedia, MediaWiki's performance and scalability have been highly optimized.[30] MediaWiki supports Squid, load-balanced database replication, client-side caching, memcached or table-based caching for frequently accessed processing of query results, a simple static file cache, feature-reduced operation, revision compression, and a job queue for database operations. MediaWiki developers have attempted to optimize the software by avoiding expensive algorithms, database queries, etc., caching every result that is expensive and has temporal locality of reference, and focusing on the hot spots in the code through profiling.[131]
+
+MediaWiki code is designed to allow for data to be written to a master database and read from slave databases, although the master can be used for some read operations if the slaves are not yet up to date. Metadata, such as article revision history, article relations (links, categories etc.), user accounts and settings can be stored in core databases and cached; the actual revision text, being more rarely used, can be stored as append-only blobs in external storage.  The software is suitable for the operation of large scale wiki farms such as Wikimedia, which had about 800 wikis as of August 2011. However, MediaWiki comes with no built-in GUI to manage such installations.
+
+Empirical evidence shows most revisions in MediaWiki databases tend to differ only slightly from previous revisions. Therefore, subsequent revisions of an article can be concatenated and then compressed, achieving very high data compression ratios of up to 100x.[131]
+
+For more information on the architecture, such as how it stores wikitext and assembles a page, see External links.
+
+The parser serves as the de facto standard for the MediaWiki syntax, as no formal syntax has been defined. Due to this lack of a formal definition, it has been difficult to create WYSIWYG editors for MediaWiki, although several WYSIWYG extensions do exist, including the popular VisualEditor.
+
+MediaWiki is not designed to be a suitable replacement for dedicated online forum or blogging software,[132] although extensions do exist to allow for both of these.[133][134]
+
+It is common for new MediaWiki users to make certain mistakes, such as forgetting to sign posts with four tildes (~~~~),[135] or manually entering a plaintext signature,[136] due to unfamiliarity with the idiosyncratic particulars involved in communication on MediaWiki discussion pages. On the other hand, the format of these discussion pages has been cited as a strength by one educator, who stated that it provides more fine-grain capabilities for discussion than traditional threaded discussion forums. For example, instead of 'replying' to an entire message, the participant in a discussion can create a hyperlink to a new wiki page on any word from the original page. Discussions are easier to follow since the content is available via hyperlinked wiki page, rather than a series of reply messages on a traditional threaded discussion forum. However, except in few cases, students were not using this capability, possibly because of their familiarity with the traditional linear discussion style and a lack of guidance on how to make the content more 'link-rich'.[137]
+
+MediaWiki by default has little support for the creation of dynamically assembled documents, or pages that aggregate data from other pages. Some research has been done on enabling such features directly within MediaWiki.[138] The Semantic MediaWiki extension provides these features. It is not in use on Wikipedia, but in more than 1,600 other MediaWiki installations.[139] The Wikibase Repository and Wikibase Repository client are however implemented in Wikidata and Wikipedia respectively, and to some extent provides semantic web features, and linking of centrally stored data to infoboxes in various Wikipedia articles.
+
+Upgrading MediaWiki is usually fully automated, requiring no changes to the site content or template programming. Historically troubles have been encountered when upgrading from significantly older versions.[140]
+
+MediaWiki developers have enacted security standards, both for core code and extensions.[141] SQL queries and HTML output are usually done through wrapper functions that handle validation, escaping, filtering for prevention of cross-site scripting and SQL injection.[142]  Many security issues have had to be patched after a MediaWiki version release,[143] and accordingly MediaWiki.org states, "The most important security step you can take is to keep your software up to date" by subscribing to the announcement listserv and installing security updates that are announced.[144]
+
+MediaWiki developers are spread around the world, though with a majority in the United States and Europe. Face-to-face meetings and programming sessions for MediaWiki developers have been held once or several times a year since 2004.[145]
+
+Support for MediaWiki users consists of:
+
+Users of online collaboration software are familiar with MediaWiki's functions and layout due to its noted use on Wikipedia. Compared to other wikis, MediaWiki is also fairly aesthetically pleasing, though simple, and has an easily customized side menu and stylesheet.[149] However, in one assessment in 2006, Confluence was deemed to be a superior product due to its very usable API and ability to better support multiple wikis.[108] Wiki providers Socialtext and JotSpot have/had project management features that MediaWiki lacks.[150]
+
+A study was done at the University of Hong Kong comparing TWiki to MediaWiki. The authors noted that TWiki has been considered as a collaborative tool for development of educational papers and technical projects, whereas MediaWiki's most noted use is on Wikipedia. Although both platforms allow discussion and tracking of progress, TWiki has a "Report" part that MediaWiki lacks. Students perceived MediaWiki as being easier to use and more enjoyable than TWiki. When asked whether they recommended using MediaWiki for knowledge management course group project, 15 out of 16 respondents expressed their preference for MediaWiki giving answers of great certainty, such as "of course", "for sure".[151] TWiki and MediaWiki both have flexible plug-in architecture.[152]
+
+A study that compared students' experience with MediaWiki to that with Google Documents found that students gave the latter a much higher rating on user-friendly layout.[153]

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+
+
+
+
+MediaWiki is a free and open-source wiki engine. It was developed for use on Wikipedia in 2002, and given the name "MediaWiki" in 2003.[6] It remains in use on Wikipedia and almost all other Wikimedia websites, including Wiktionary, Wikimedia Commons and Wikidata; these sites continue to define a large part of the requirement set for MediaWiki.[7] MediaWiki was originally developed by Magnus Manske and improved by Lee Daniel Crocker.[8][9] Its development has since then been coordinated by the Wikimedia Foundation.
+
+MediaWiki is written in the PHP programming language and stores all text content into a database. The software is optimized to efficiently handle large projects, which can have terabytes of content and hundreds of thousands of hits per second.[7][10] Because Wikipedia is one of the world's largest websites, achieving scalability through multiple layers of caching and database replication has been a major concern for developers. Another major aspect of MediaWiki is its internationalization; its interface is available in more than 300 languages.[11] The software has more than 1,000 configuration settings[12] and more than 1,800 extensions available for enabling various features to be added or changed.[13]
+
+Besides its use on Wikimedia sites, MediaWiki has been used as a knowledge management and content management system on many thousands of websites, public and private, including the websites Fandom, wikiHow and Gamepedia, and major internal installations like Intellipedia and Diplopedia.
+
+MediaWiki is free and open-source software and is distributed under the terms of the GNU General Public License version 2 or any later version. Its documentation, located at www.mediawiki.org, is released under the Creative Commons BY-SA 3.0 license and partly in the public domain.[14] Specifically, the manuals and other content at MediaWiki.org are Creative Commons-licensed, while the set of help pages intended to be freely copied into fresh wiki installations and/or distributed with MediaWiki software is public domain. This was done to eliminate legal issues arising from the help pages being imported into wikis with licenses that are incompatible with the Creative Commons license.[15] MediaWiki development has generally favored the use of open-source media formats.[16]
+
+MediaWiki has an active volunteer community for development and maintenance. Users who have made meaningful contributions to the project by submitting patches are generally, upon request, granted access to commit revisions to the project's Git/Gerrit repository.[17]
+There are also paid programmers who primarily develop projects for the Wikimedia Foundation. MediaWiki developers participate in the Google Summer of Code by facilitating the assignment of mentors to students wishing to work on MediaWiki core and extension projects.[18]
+During the year prior to November 2012, there were about two hundred developers who had committed changes to the MediaWiki core or extensions.[19]
+Major MediaWiki releases are generated approximately every six months by taking snapshots of the development branch, which is kept continuously in a runnable state;[20] minor releases, or point releases, are issued as needed to correct bugs (especially security problems).
+
+MediaWiki also has a public bug tracker, phabricator.wikimedia.org, which runs Phabricator. The site is also used for feature and enhancement requests.
+
+When Wikipedia was launched in January 2001, it ran on the existing wiki software, UseModWiki. UseModWiki is written in the Perl programming language, and stores all wiki pages, in text (.txt) files. This software soon proved to be limiting, in both functionality and performance. In mid-2001, Magnus Manske — a developer and student at the University of Cologne, as well as, a Wikipedia editor — began working on new software that would replace UseModWiki, specifically designed for use by Wikipedia. This software was written in the PHP scripting language, and stored all of its information in a MySQL engine database. The new software was largely developed by August 24, 2001, and a test wiki for it was established shortly thereafter.
+
+The first, full–implementation of this software, was the new Meta Wikipedia on November 9, 2001. There was a desire to have it implemented immediately on the English-language Wikipedia,[21] however, Manske was apprehensive about any potential bugs harming the nascent website during the period of the final exams he had to complete immediately prior to Christmas;[22] this led to the launch on the English-language Wikipedia being delayed until January 25, 2002. The software was then, gradually, deployed on all the Wikipedia language sites of that time. This software was referred to as "the PHP script" and as "phase II", with the name "phase I", retroactively given to the use of UseModWiki.
+
+Increasing usage soon caused load problems to arise again, and soon after, another rewrite of the software began; this time being done by Lee Daniel Crocker, which became known as "phase III". This new software was also written in PHP, with a MySQL back-end, and kept the basic interface of the phase II software, but with the added functionality of a wider scalability. The "phase III" software went live on Wikipedia in July 2002.
+
+The Wikimedia Foundation was announced on June 20, 2003. In July, Wikipedia contributor Daniel Mayer, suggested the name "MediaWiki" for the software, as a play on "Wikimedia".[23] The MediaWiki name, was gradually phased in, beginning in August 2003. The name has frequently caused confusion due to its (intentional) similarity to the "Wikimedia" name (which itself is similar to "Wikipedia").[24]
+
+The product logo was created by Erik Möller, using a flower photograph taken by Florence Nibart-Devouard, and was originally submitted to the logo contest for a new Wikipedia logo, held in from July 20 to August 27, 2003.[25][26] The logo came in 3rd place, and was chosen to represent MediaWiki rather than Wikipedia, with the 2nd place logo being used for the Wikimedia Foundation.[27] The double square brackets ([[ ]]) symbolize the syntax MediaWiki uses for creating hyperlinks to other wiki pages; while the sunflower, represents the: diversity of content on Wikipedia, the constant growth, and also the wildness.[28]
+
+Later, Brion Vibber, the Chief Technical Officer of the Wikimedia Foundation,[29] took up the role of Release Manager, and the most active Developer.[6][30]
+
+Major milestones in MediaWiki's development have included: the categorization system (2004); Parser Functions, (2006); Flagged Revisions, (2008);[31] the "ResourceLoader", a delivery system for CSS and JavaScript (2011);[32] and the VisualEditor, a "what you see is what you get" (WYSIWYG) editing platform (2013).[33]
+
+The first version of MediaWiki, 1.1, was released in December 2003.
+
+MediaWiki's most famous use has been in Wikipedia and, to a lesser degree, the Wikimedia Foundation's other projects. Fandom, a wiki hosting service formerly known as Wikia, runs on MediaWiki. Other public wikis that run on MediaWiki include wikiHow and SNPedia. WikiLeaks began as a MediaWiki-based site, but is no longer a wiki.
+
+A number of alternative wiki encyclopedias to Wikipedia run on MediaWiki, including Citizendium, Metapedia, Scholarpedia and Conservapedia. MediaWiki is also used internally by a large number of companies, including Novell and Intel.[34][35]
+
+Notable usages of MediaWiki within governments include Intellipedia, used by the United States Intelligence Community, Diplopedia, used by the United States Department of State, and milWiki, a part of milSuite used by the United States Department of Defense. United Nations agencies such as the United Nations Development Programme and INSTRAW chose to implement their wikis using MediaWiki, because "this software runs Wikipedia and is therefore guaranteed to be thoroughly tested, will continue to be developed well into the future, and future technicians on these wikis will be more likely to have exposure to MediaWiki than any other wiki software."[36]
+
+The Free Software Foundation uses MediaWiki to implement the LibrePlanet site.[37]
+
+MediaWiki provides a rich core feature set and a mechanism to attach extensions to provide additional functionality.
+
+Due to the strong emphasis on multilingualism in the Wikimedia projects, internationalization and localization has received significant attention by developers. The user interface has been fully or partially translated into more than 300 languages on translatewiki.net,[11] and can be further customized by site administrators (the entire interface is editable through the wiki).
+
+Several extensions, most notably those collected in the MediaWiki Language Extension Bundle, are designed to further enhance the multilingualism and internationalization of MediaWiki.
+
+Installation of MediaWiki requires that the user have administrative privileges on a server running both PHP and a compatible type of SQL database. Some users find that setting up a virtual host is helpful if the majority of one's site runs under a framework (such as Zope or Ruby on Rails) that is largely incompatible with MediaWiki.[38] Cloud hosting can eliminate the need to deploy a new server.[39]
+
+An installation PHP script is accessed via a web browser to initialize the wiki's settings. It prompts the user for a minimal set of required parameters, leaving further changes, such as enabling uploads,[40] adding a site logo,[41] and installing extensions, to be made by modifying configuration settings contained in a file called LocalSettings.php.[42] Some aspects of MediaWiki can be configured through special pages or by editing certain pages; for instance, abuse filters can be configured through a special page,[43] and certain gadgets can be added by creating JavaScript pages in the MediaWiki namespace.[44] The MediaWiki community publishes a comprehensive installation guide.[45]
+
+One of the earliest differences between MediaWiki (and its predecessor, UseModWiki) and other wiki engines was the use of "free links" instead of CamelCase. When MediaWiki was created, it was typical for wikis to require text like "WorldWideWeb" to create a link to a page about the World Wide Web; links in MediaWiki, on the other hand, are created by surrounding words with double square brackets, and any spaces between them are left intact, e.g. [[World Wide Web]]. This change was logical for the purpose of creating an encyclopedia, where accuracy in titles is important.
+
+MediaWiki uses an extensible[46] lightweight wiki markup designed to be easier to use and learn than HTML. Tools exist for converting content such as tables between MediaWiki markup and HTML.[47] Efforts have been made to create a MediaWiki markup spec, but a consensus seems to have been reached that Wikicode requires context-sensitive grammar rules.[48][49] The following side-by-side comparison illustrates the differences between wiki markup and HTML:
+
+"Take some more tea," the March Hare said to Alice, very earnestly.
+
+"I've had nothing yet," Alice replied in an offended tone: "so I can't take more."
+
+"You mean you can't take less," said the Hatter: "it's very easy to take more than nothing."
+
+(Quotation above from Alice's Adventures in Wonderland by Lewis Carroll)
+
+MediaWiki's default page-editing tools have been described as somewhat challenging to learn.[50] A survey of students assigned to use a MediaWiki-based wiki found that when they were asked an open question about main problems with the wiki, 24% cited technical problems with formatting, e.g. "Couldn't figure out how to get an image in. Can't figure out how to show a link with words; it inserts a number."[51]
+
+To make editing long pages easier, MediaWiki allows the editing of a subsection of a page (as identified by its header). A registered user can also indicate whether or not an edit is minor. Correcting spelling, grammar or punctuation are examples of minor edits, whereas adding paragraphs of new text is an example of a non-minor edit.
+
+Sometimes while one user is editing, a second user saves an edit to the same part of the page. Then, when the first user attempts to save the page, an edit conflict occurs. The second user is then given an opportunity to merge their content into the page as it now exists following the first user's page save.
+
+MediaWiki's user interface has been localized in many different languages. A language for the wiki content itself can also be set, to be sent in the "Content-Language" HTTP header and "lang" HTML attribute.
+
+MediaWiki has an extensible web API (application programming interface) that provides direct, high-level access to the data contained in the MediaWiki databases. Client programs can use the API to log in, get data, and post changes. The API supports thin web-based JavaScript clients and end-user applications (such as vandal-fighting tools). The API can be accessed by the backend of another web site.[52] An extensive Python bot library, Pywikibot,[53] and a popular semi-automated tool called AutoWikiBrowser, also interface with the API.[54] The API is accessed via URLs such as http://en.wikipedia.org/w/api.php?action=query&list=recentchanges. In this case, the query would be asking Wikipedia for information relating to the last 10 edits to the site. One of the perceived advantages of the API is its language independence; it listens for HTTP connections from clients and can send a response in a variety of formats, such as XML, serialized PHP, or JSON.[55] Client code has been developed to provide layers of abstraction to the API.[56]
+
+MediaWiki supports rich content generated through specialized syntax. For example, the software comes with optional support for rendering mathematical formulas using LaTeX and a special parser written in OCaml. Similar functionality for other content, ranging from graphical timelines over mathematical plotting and musical scores to Egyptian hieroglyphs, is available via extensions.
+
+The software has become more powerful at dealing with a wide variety of uploaded media files. Its richest functionality is in the area of images, where image galleries and thumbnails can be generated with relative ease. There is also support for Exif metadata. The use of MediaWiki to operate the Wikimedia Commons, one of the largest free content media archives, has driven the need for further functionality in this area.
+
+Because any WYSIWYG editor would have to know wikitext grammar, and no full grammar for wikitext exists, MediaWiki currently provides no native WYSIWYG support.[57] It does come with a customizable graphical toolbar for simplifying the process of learning the wiki syntax.[58] Various extensions exist for handling WYSIWYG editing to different degrees.[59]
+
+Among the features of MediaWiki to assist in tracking edits is a Recent Changes feature that provides a list of recent edits to the wiki. This list contains basic information about those edits such as the editing user, the edit summary, the page edited, as well as any tags (e.g. "possible malware link")[60] added by customizable abuse filters and other extensions to aid in combating unhelpful edits.[61] On more active wikis, so many edits occur that it is hard to track Recent Changes manually. Anti-vandal software, including user-assisted tools[62] are sometimes employed on such wikis to process Recent Changes items. Server load can be reduced by sending a continuous feed of Recent Changes to an IRC channel that these tools can monitor, eliminating their need to send requests for a refreshed Recent Changes feed to the API.[63][64]
+
+Another important tool is watchlisting. Each logged-in user has a watchlist to which the user can add whatever pages he or she wishes. When an edit is made to one of those pages, a summary of that edit appears on the watchlist the next time it is refreshed.[65] As with the recent changes page, recent edits that appear on the watchlist contain clickable links for easy review of the article history and specific changes made.
+
+There is also capability to review all edits made by any particular user. In this way, if an edit is identified as problematic, it is possible to check the user's other edits for issues.
+
+MediaWiki allows one to link to specific versions of articles. This has been useful to the scientific community, in that expert peer reviewers could analyse articles, improve them and provide links to the trusted version of that article.[66]
+
+Navigation through the wiki is largely through internal wikilinks. MediaWiki's wikilinks implement page existence detection, in which a link is colored blue if the target page exists on the local wiki and red if it does not. If a user clicks on a red link, they are prompted to create an article with that title. Page existence detection makes it practical for users to create "wikified" articles — that is, articles containing links to other pertinent subjects — without those other articles being yet in existence.
+
+Interwiki links function much the same way as namespaces. A set of interwiki prefixes can be configured to cause, for instance, a page title of wikiquote:Jimbo Wales to direct the user to the Jimbo Wales article on Wikiquote.[67] Unlike internal wikilinks, interwiki links lack page existence detection functionality, and accordingly there is no way to tell whether a blue interwiki link is broken or not.
+
+Page tabs are displayed at the top of pages. These tabs allow users to perform actions or view pages that are related to the current page. The available default actions include viewing, editing, and discussing the current page. The specific tabs displayed depend on whether or not the user is logged into the wiki and whether the user has sysop privileges on the wiki. For instance, the ability to move a page or add it to one's watchlist is usually restricted to logged-in users. The site administrator can add or remove tabs by using JavaScript or installing extensions.[68]
+
+Each page has an associated history page from which the user can access every version of the page that has ever existed and generate diffs between two versions of his choice. Users' contributions are displayed not only here, but also via a "user contributions" option on a sidebar. Carl Challborn & Teresa Reimann note that "While this feature may be a slight deviation from the collaborative, 'ego-less' spirit of wiki purists, it can be
+very useful for educators who need to assess the contribution and participation of individual student users."[69]
+
+MediaWiki provides many features beyond hyperlinks for structuring content. One of the earliest such features is namespaces. One of Wikipedia's earliest problems had been the separation of encyclopedic content from pages pertaining to maintenance and communal discussion, as well as personal pages about encyclopedia editors. Namespaces are prefixes before a page title (such as "User:" or "Talk:") that serve as descriptors for the page's purpose and allow multiple pages with different functions to exist under the same title. For instance, a page titled "[[The Terminator]]", in the default namespace, could describe the 1984 movie starring Arnold Schwarzenegger, while a page titled "[[User:The Terminator]]" could be a profile describing a user who chooses this name as a pseudonym. More commonly, each namespace has an associated "Talk:" namespace, which can be used to discuss its contents, such as "User talk:" or "Template talk:". The purpose of having discussion pages is to allow content to be separated from discussion surrounding the content.[70][71]
+
+Namespaces can be viewed as folders that separate different basic types of information or functionality. Custom namespaces can be added by the site administrators. There are 16 namespaces by default for content, with 2 "pseudo-namespaces" used for dynamically generated "Special:" pages and links to media files. Each namespace on MediaWiki is numbered: content page namespaces have even numbers and their associated talk page namespaces have odd numbers.[72]
+
+Users can create new categories and add pages and files to those categories by appending one or more category tags to the content text. Adding these tags creates links at the bottom of the page that take the reader to the list of all pages in that category, making it easy to browse related articles.[73] The use of categorization to organize content has been described as a combination of:
+
+In addition to namespaces, content can be ordered using subpages. This simple feature provides automatic breadcrumbs of the pattern [[Page title/Subpage title]] from the page after the slash (in this case, "Subpage title") to the page before the slash (in this case, "Page title").
+
+If the feature is enabled, users can customize their stylesheets and configure client-side JavaScript to be executed with every pageview. On Wikipedia, this has led to a large number of additional tools and helpers developed through the wiki and shared among users. For instance, navigation popups is a custom JavaScript tool that shows previews of articles when the user hovers over links, and also provides shortcuts for common maintenance tasks.[75]
+
+The entire MediaWiki user interface can be edited through the wiki itself by users with the necessary permissions (typically called "administrators"). This is done through a special namespace with the prefix "MediaWiki:", where each page title identifies a particular user interface message. Using an extension,[76] it is also possible for a user to create personal scripts, and to choose whether certain sitewide scripts should apply to them by toggling the appropriate options in the user preferences page.
+
+The "MediaWiki:" namespace was also originally used for creating custom text blocks that could then be dynamically loaded into other pages using a special syntax. This content was later moved into its own namespace, "Template:".
+
+Templates are text blocks that can be dynamically loaded inside another page whenever that page is requested. The template is a special link in double curly brackets (for example "{{Disputed|date=October 2018}}"), which calls the template (in this case located at Template:Disputed) to load in place of the template call.
+
+Templates are structured documents containing attribute–value pairs. They are defined with parameters, to which are assigned values when transcluded on an article page. The name of the parameter is delimited from the value by an equals sign. A class of templates known as infoboxes is used on Wikipedia to collect and present a subset of information about its subject, usually on the top (mobile view) or top right-hand corner (desktop view) of the document.
+
+A related method, called template substitution (called by adding subst: at the beginning of a template link) inserts (like a copy and paste operation) the contents of the template into the target page, instead of loading the template contents dynamically whenever the page is loaded. This can lead to inconsistency when using templates, but may be useful in certain cases, and in most cases requires fewer server resources (the actual amount of savings can vary depending on wiki configuration and the complexity of the template).
+
+Templates have found many different uses. Templates enable users to create complex table layouts that are used consistently across multiple pages, and where only the content of the tables gets inserted using template parameters. Templates are often used to identify problems with a Wikipedia article by putting a template in the article. This template then outputs a graphical box stating that the article content is disputed or in need of some other attention, and also categorize it so that articles of this nature can be located. Templates are also used on user pages to send users standard messages welcoming them to the site,[77] giving them awards for outstanding contributions,[78][79] warning them when their behavior is considered inappropriate,[80] notifying them when they are blocked from editing,[81] and so on.
+
+MediaWiki offers flexibility in creating and defining user groups. For instance, it would be possible to create an arbitrary "ninja" group that can block users and delete pages, and whose edits are hidden by default in the recent changes log. It is also possible to set up a group of "autoconfirmed" users that one becomes a member of after making a certain number of edits and waiting a certain number of days.[82] Some groups that are enabled by default are bureaucrats and sysops. Bureaucrats have power to change other users' rights. Sysops have power over page protection and deletion and the blocking of users from editing. MediaWiki's available controls on editing rights have been deemed sufficient for publishing and maintaining important documents such as a manual of standard operating procedures in a hospital.[83]
+
+When a page consists only of useless content, there are several ways to remove that content. The simplest way, available to all users, is simply to blank the page. However, this interferes with page existence detection, unless an extension is installed to treat blanked pages as though they were nonexistent.[84] Blanking also leaves the content accessible through the history page, an outcome that, while potentially increasing transparency by allowing non-sysops to easily review the content removal decision for appropriateness, might be unacceptable or even unlawful[85] in some cases. Another option is for a sysop to delete the page, and thereby prevent it from being viewed by non-sysops. Another level of deletion, called RevisionDelete, can be used by a group (e.g. "Oversighters") to prevent a page from being viewed by non-members of that group.[86] It is also possible, using certain extensions, to remove content from being viewed through any of the normal channels on the wiki,[87] or even to completely delete revisions from the database.[88]
+
+MediaWiki comes with a basic set of features related to restricting access, but its original and ongoing design is driven by functions that largely relate to content, not content segregation. As a result, with minimal exceptions (related to specific tools and their related "Special" pages), page access control has never been a high priority in core development and developers have stated that users requiring secure user access and authorization controls should not rely on MediaWiki, since it was never designed for these kinds of situations. For instance, it is extremely difficult to create a wiki where only certain users can read and access some pages.[89] Here, wiki engines like Foswiki, MoinMoin and Confluence provide more flexibility by supporting advanced security mechanisms like access control lists.
+
+The MediaWiki codebase contains various "hooks" using callback functions to add additional PHP code in an extensible way. This allows developers to write extensions without necessarily needing to modify the core or having to submit their code for review. Installing an extension typically consists of adding a line to the configuration file, though in some cases additional changes such as database updates or core patches are required.
+
+Five main extension points were created to allow developers to add features and functionalities to MediaWiki. Hooks are run every time a certain event happens; for instance, the ArticleSaveComplete hook occurs after a save article request has been processed.[90] This can be used, for example, by an extension that notifies selected users whenever a page edit occurs on the wiki from new or anonymous users.[91] New tags can be created to process data with opening and closing tags (<newtag>...</newtag>).[92] Parser functions can be used to create a new command ({{#if:...|...|...}}).[93] New special pages can be created to perform a specific function. These pages are dynamically generated. For example, a special page might show all pages that have one or more links to an external site or it might create a form providing user submitted feedback.[94] Skins allow users to customize the look and feel of MediaWiki.[95] A minor extension point allows the use of Amazon S3 to host image files.[96]
+
+MediaWiki can be made more advanced and useful for various purposes through its extensions. These extensions vary greatly in complexity.
+
+The Wikimedia Foundation operates a Git server where many extensions host their repository. Most of them also have a documentation page on the MediaWiki website.
+
+MediaWiki code review was itself historically facilitated through a MediaWiki extension.[97] As of March 2012, it has been done through Gerrit.
+
+Since version 1.16, MediaWiki uses the jQuery library.[98]
+
+Among the most popular extensions is a parser function extension, ParserFunctions, which allows different content to be rendered based on the result of conditional statements.[99] These conditional statements can perform functions such as evaluating whether a parameter is empty, comparing strings, evaluating mathematical expressions, and returning one of two values depending on whether a page exists. It was designed as a replacement for a notoriously inefficient template called {{Qif}}.[100] Schindler recounts the history of the ParserFunctions extension as follows:[31]
+
+In 2006 some Wikipedians discovered that through an intricate and complicated interplay of templating features and CSS they could create conditional wiki text, i.e. text that was displayed if a template parameter had a specific value. This included repeated calls of templates within templates, which bogged down the performance of the whole system. The developers faced the choice of either disallowing the spreading of an obviously desired feature by detecting such usage and explicitly disallowing it within the software, or offer an efficient alternative. The latter was done by Tim Starling, who announced the introduction of parser functions, wiki text that calls functions implemented in the underlying software.
+At first, only conditional text and the computation of simple mathematical expressions was implemented, but this already increased the possibilities for wiki editors enormously. With time further parser functions were introduced, finally leading to a framework that allowed the simple writing of extension function to add arbitrary functionalities, like e.g. geo-coding services or widgets. This time the developers were clearly reacting to the demand of the community, being forced either to fight the solution of the issue that the community had (i.e. conditional text), or offer an improved technical implementation to replace the previous practice and achieve an overall better performance.
+
+Another parser functions extension, StringFunctions, was developed to allow evaluation of string length, string position, and so on. Wikimedia communities, having created awkward workarounds to accomplish the same functionality,[101] clamored for it to be enabled on their projects.[102] Much of its functionality was eventually integrated into the ParserFunctions extension,[103] albeit disabled by default and accompanied by a warning from Tim Starling that enabling string functions would allow users "to implement their own parsers in the ugliest, most inefficient programming language known to man: MediaWiki wikitext with ParserFunctions."[104]
+
+Since 2012 an extension, Scribunto, has existed that allows for the creation of "modules" — wiki pages written in the scripting language Lua — which can then be run within templates and standard wiki pages. Scribunto has been installed on Wikipedia and other Wikimedia sites since 2013, and is used heavily on those sites. Scribunto code runs significantly faster than corresponding wikitext code using ParserFunctions.[105]
+
+Another very popular extension is a citation extension that enables footnotes to be added to pages using inline references.[106] This extension has, however, been criticized for being difficult to use and requiring the user to memorize complex syntax. A gadget called RefToolbar attempts to make it easier to create citations using common templates. MediaWiki has some extensions that are well-suited for academia, such as mathematics extensions[107] and an extension that allows molecules to be rendered in 3D.[108]
+
+A generic Widgets extension exists that allows MediaWiki to integrate with virtually anything. Other examples of extensions that could improve a wiki are category suggestion extensions[109] and extensions for inclusion of Flash Videos,[110] YouTube videos,[111] and RSS feeds.[112] Metavid, a site that archives video footage of the U.S. Senate and House floor proceedings, was created using code extending MediaWiki into the domain of collaborative video authoring.[113]
+
+There are many spambots that search the web for MediaWiki installations and add linkspam to them, despite the fact that MediaWiki uses the nofollow attribute to discourage such attempts at search engine optimization.[114] Part of the problem is that third party republishers, such as mirrors, may not independently implement the nofollow tag on their websites, so marketers can still get PageRank benefit by inserting links into pages when those entries appear on third party websites.[115] Anti-spam extensions have been developed to combat the problem by introducing CAPTCHAs,[116] blacklisting certain URLs,[117] and allowing bulk deletion of pages recently added by a particular user.[118]
+
+MediaWiki comes pre-installed with a standard text-based search. Extensions exist to let MediaWiki use more sophisticated third-party search engines, including Elasticsearch (which since 2014 has been in use on Wikipedia), Lucene[119] and Sphinx.[120]
+
+Various MediaWiki extensions have also been created to allow for more complex, faceted search, on both data entered within the wiki and on metadata such as pages' revision history.[121][122] Semantic MediaWiki is one such extension.[123][124]
+
+MediaWiki can use either the MySQL/MariaDB, PostgreSQL or SQLite relational database management system. There is limited support for Oracle Database and Microsoft SQL Server.[125] A MediaWiki database contains several dozen tables, including a page table that contains page titles, page ids, and other metadata;[126] and a revision table to which is added a new row every time an edit is made, containing the page id, a brief textual summary of the change performed, the user name of the article editor (or its IP address the case of an unregistered user) and a timestamp.[127][128]
+
+In a 4½ year period, the MediaWiki database had 170 schema versions.[129] Possibly the largest schema change was done in MediaWiki 1.5, when the storage of metadata was separated from that of content, to improve performance flexibility. When this upgrade was applied to Wikipedia, the site was locked for editing, and the schema was converted to the new version in about 22 hours. Some software enhancement proposals, such as a proposal to allow sections of articles to be watched via watchlist, have been rejected because the necessary schema changes would have required excessive Wikipedia downtime.[130]
+
+Because it is used to run one of the highest-traffic sites on the Web, Wikipedia, MediaWiki's performance and scalability have been highly optimized.[30] MediaWiki supports Squid, load-balanced database replication, client-side caching, memcached or table-based caching for frequently accessed processing of query results, a simple static file cache, feature-reduced operation, revision compression, and a job queue for database operations. MediaWiki developers have attempted to optimize the software by avoiding expensive algorithms, database queries, etc., caching every result that is expensive and has temporal locality of reference, and focusing on the hot spots in the code through profiling.[131]
+
+MediaWiki code is designed to allow for data to be written to a master database and read from slave databases, although the master can be used for some read operations if the slaves are not yet up to date. Metadata, such as article revision history, article relations (links, categories etc.), user accounts and settings can be stored in core databases and cached; the actual revision text, being more rarely used, can be stored as append-only blobs in external storage.  The software is suitable for the operation of large scale wiki farms such as Wikimedia, which had about 800 wikis as of August 2011. However, MediaWiki comes with no built-in GUI to manage such installations.
+
+Empirical evidence shows most revisions in MediaWiki databases tend to differ only slightly from previous revisions. Therefore, subsequent revisions of an article can be concatenated and then compressed, achieving very high data compression ratios of up to 100x.[131]
+
+For more information on the architecture, such as how it stores wikitext and assembles a page, see External links.
+
+The parser serves as the de facto standard for the MediaWiki syntax, as no formal syntax has been defined. Due to this lack of a formal definition, it has been difficult to create WYSIWYG editors for MediaWiki, although several WYSIWYG extensions do exist, including the popular VisualEditor.
+
+MediaWiki is not designed to be a suitable replacement for dedicated online forum or blogging software,[132] although extensions do exist to allow for both of these.[133][134]
+
+It is common for new MediaWiki users to make certain mistakes, such as forgetting to sign posts with four tildes (~~~~),[135] or manually entering a plaintext signature,[136] due to unfamiliarity with the idiosyncratic particulars involved in communication on MediaWiki discussion pages. On the other hand, the format of these discussion pages has been cited as a strength by one educator, who stated that it provides more fine-grain capabilities for discussion than traditional threaded discussion forums. For example, instead of 'replying' to an entire message, the participant in a discussion can create a hyperlink to a new wiki page on any word from the original page. Discussions are easier to follow since the content is available via hyperlinked wiki page, rather than a series of reply messages on a traditional threaded discussion forum. However, except in few cases, students were not using this capability, possibly because of their familiarity with the traditional linear discussion style and a lack of guidance on how to make the content more 'link-rich'.[137]
+
+MediaWiki by default has little support for the creation of dynamically assembled documents, or pages that aggregate data from other pages. Some research has been done on enabling such features directly within MediaWiki.[138] The Semantic MediaWiki extension provides these features. It is not in use on Wikipedia, but in more than 1,600 other MediaWiki installations.[139] The Wikibase Repository and Wikibase Repository client are however implemented in Wikidata and Wikipedia respectively, and to some extent provides semantic web features, and linking of centrally stored data to infoboxes in various Wikipedia articles.
+
+Upgrading MediaWiki is usually fully automated, requiring no changes to the site content or template programming. Historically troubles have been encountered when upgrading from significantly older versions.[140]
+
+MediaWiki developers have enacted security standards, both for core code and extensions.[141] SQL queries and HTML output are usually done through wrapper functions that handle validation, escaping, filtering for prevention of cross-site scripting and SQL injection.[142]  Many security issues have had to be patched after a MediaWiki version release,[143] and accordingly MediaWiki.org states, "The most important security step you can take is to keep your software up to date" by subscribing to the announcement listserv and installing security updates that are announced.[144]
+
+MediaWiki developers are spread around the world, though with a majority in the United States and Europe. Face-to-face meetings and programming sessions for MediaWiki developers have been held once or several times a year since 2004.[145]
+
+Support for MediaWiki users consists of:
+
+Users of online collaboration software are familiar with MediaWiki's functions and layout due to its noted use on Wikipedia. Compared to other wikis, MediaWiki is also fairly aesthetically pleasing, though simple, and has an easily customized side menu and stylesheet.[149] However, in one assessment in 2006, Confluence was deemed to be a superior product due to its very usable API and ability to better support multiple wikis.[108] Wiki providers Socialtext and JotSpot have/had project management features that MediaWiki lacks.[150]
+
+A study was done at the University of Hong Kong comparing TWiki to MediaWiki. The authors noted that TWiki has been considered as a collaborative tool for development of educational papers and technical projects, whereas MediaWiki's most noted use is on Wikipedia. Although both platforms allow discussion and tracking of progress, TWiki has a "Report" part that MediaWiki lacks. Students perceived MediaWiki as being easier to use and more enjoyable than TWiki. When asked whether they recommended using MediaWiki for knowledge management course group project, 15 out of 16 respondents expressed their preference for MediaWiki giving answers of great certainty, such as "of course", "for sure".[151] TWiki and MediaWiki both have flexible plug-in architecture.[152]
+
+A study that compared students' experience with MediaWiki to that with Google Documents found that students gave the latter a much higher rating on user-friendly layout.[153]

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+In the history of Europe, the Middle Ages or  Medieval Period lasted from the 5th to the 15th century. It began with the fall of the Western Roman Empire and merged into the Renaissance and the Age of Discovery. The Middle Ages is the middle period of the three traditional divisions of Western history: classical antiquity, the medieval period, and the modern period. The medieval period is itself subdivided into the Early, High, and Late Middle Ages.
+
+Population decline, counterurbanisation, collapse of centralized authority, invasions, and mass migrations of tribes, which had begun in Late Antiquity, continued in the Early Middle Ages. The large-scale movements of the Migration Period, including various Germanic peoples, formed new kingdoms in what remained of the Western Roman Empire. In the 7th century, North Africa and the Middle East—once part of the Byzantine Empire—came under the rule of the Umayyad Caliphate, an Islamic empire, after conquest by Muhammad's successors.  Although there were substantial changes in society and political structures, the break with classical antiquity was not complete. The still-sizeable Byzantine Empire, Rome's direct continuation, survived in the Eastern Mediterranean and remained a major power. The empire's law code, the Corpus Juris Civilis or "Code of Justinian", was rediscovered in Northern Italy in 1070 and became widely admired later in the Middle Ages.  In the West, most kingdoms incorporated the few extant Roman institutions. Monasteries were founded as campaigns to Christianise pagan Europe continued. The Franks, under the Carolingian dynasty, briefly established the Carolingian Empire during the later 8th and early 9th centuries. It covered much of Western Europe but later succumbed to the pressures of internal civil wars combined with external invasions: Vikings from the north, Magyars from the east, and Saracens from the south.
+
+During the High Middle Ages, which began after 1000, the population of Europe increased greatly as technological and agricultural innovations allowed trade to flourish and the Medieval Warm Period climate change allowed crop yields to increase. Manorialism, the organisation of peasants into villages that owed rent and labour services to the nobles, and feudalism, the political structure whereby knights and lower-status nobles owed military service to their overlords in return for the right to rent from lands and manors, were two of the ways society was organised in the High Middle Ages. The Crusades, first preached in 1095, were military attempts by Western European Christians to regain control of the Holy Land from Muslims. Kings became the heads of centralised nation-states, reducing crime and violence but making the ideal of a unified Christendom more distant. Intellectual life was marked by scholasticism, a philosophy that emphasised joining faith to reason, and by the founding of universities. The theology of Thomas Aquinas, the paintings of Giotto, the poetry of Dante and Chaucer, the travels of Marco Polo, and the Gothic architecture of cathedrals such as Chartres are among the outstanding achievements toward the end of this period and into the Late Middle Ages.
+
+The Late Middle Ages was marked by difficulties and calamities including famine, plague, and war, which significantly diminished the population of Europe; between 1347 and 1350, the Black Death killed about a third of Europeans. Controversy, heresy, and the Western Schism within the Catholic Church paralleled the interstate conflict, civil strife, and peasant revolts that occurred in the kingdoms. Cultural and technological developments transformed European society, concluding the Late Middle Ages and beginning the early modern period.
+
+The Middle Ages is one of the three major periods in the most enduring scheme for analysing European history: classical civilisation or Antiquity, the Middle Ages and the Modern Period.[1] The "Middle Ages" first appears in Latin in 1469 as media tempestas or "middle season".[2][A] In early usage, there were many variants, including medium aevum, or "middle age", first recorded in 1604,[4] and media saecula, or "middle centuries", first recorded in 1625.[5] The adjective "medieval" (or sometimes "mediaeval"[6] or "mediæval"),[7] meaning pertaining to the Middle Ages, derives from medium aevum.[6]
+
+Medieval writers divided history into periods such as the "Six Ages" or the "Four Empires", and considered their time to be the last before the end of the world.[8] When referring to their own times, they spoke of them as being "modern".[9] In the 1330s, the humanist and poet Petrarch referred to pre-Christian times as antiqua (or "ancient") and to the Christian period as nova (or "new").[10] Leonardo Bruni was the first historian to use tripartite periodisation in his History of the Florentine People (1442), with a middle period "between the fall of the Roman Empire and the revival of city life sometime in late eleventh and twelfth centuries".[11] Tripartite periodisation became standard after the 17th-century German historian Christoph Cellarius divided history into three periods: ancient, medieval, and modern.[5]
+
+The most commonly given starting point for the Middle Ages is around 500,[12] with the date of 476 first used by Bruni.[11][B] Later starting dates are sometimes used in the outer parts of Europe.[14] For Europe as a whole, 1500 is often considered to be the end of the Middle Ages,[15] but there is no universally agreed upon end date. Depending on the context, events such as the conquest of Constantinople by the Turks in 1453, Christopher Columbus's first voyage to the Americas in 1492,  or the Protestant Reformation in 1517 are sometimes used.[16] English historians often use the Battle of Bosworth Field in 1485 to mark the end of the period.[17] For Spain, dates commonly used are the death of King Ferdinand II in 1516, the death of Queen Isabella I of Castile in 1504, or the conquest of Granada in 1492.[18]
+
+Historians from Romance-speaking countries tend to divide the Middle Ages into two parts: an earlier "High" and later "Low" period. English-speaking historians, following their German counterparts, generally subdivide the Middle Ages into three intervals: "Early", "High", and "Late".[1] In the 19th century, the entire Middle Ages were often referred to as the "Dark Ages",[19][C] but with the adoption of these subdivisions, use of this term was restricted to the Early Middle Ages, at least among historians.[8]
+
+The Roman Empire reached its greatest territorial extent during the 2nd century AD; the following two centuries witnessed the slow decline of Roman control over its outlying territories.[21] Economic issues, including inflation, and external pressure on the frontiers combined to create the Crisis of the Third Century, with emperors coming to the throne only to be rapidly replaced by new usurpers.[22] Military expenses increased steadily during the 3rd century, mainly in response to the war with the Sasanian Empire, which revived in the middle of the 3rd century.[23] The army doubled in size, and cavalry and smaller units replaced the Roman legion as the main tactical unit.[24] The need for revenue led to increased taxes and a decline in numbers of the curial, or landowning, class, and decreasing numbers of them willing to shoulder the burdens of holding office in their native towns.[23] More bureaucrats were needed in the central administration to deal with the needs of the army, which led to complaints from civilians that there were more tax-collectors in the empire than tax-payers.[24]
+
+The Emperor Diocletian (r. 284–305) split the empire into separately administered eastern and western halves in 286; the empire was not considered divided by its inhabitants or rulers, as legal and administrative promulgations in one division were considered valid in the other.[25][D] In 330, after a period of civil war, Constantine the Great (r. 306–337) refounded the city of Byzantium as the newly renamed eastern capital, Constantinople.[26] Diocletian's reforms strengthened the governmental bureaucracy, reformed taxation, and strengthened the army, which bought the empire time but did not resolve the problems it was facing: excessive taxation, a declining birthrate, and pressures on its frontiers, among others.[27] Civil war between rival emperors became common in the middle of the 4th century, diverting soldiers from the empire's frontier forces and allowing invaders to encroach.[28] For much of the 4th century, Roman society stabilised in a new form that differed from the earlier classical period, with a widening gulf between the rich and poor, and a decline in the vitality of the smaller towns.[29] Another change was the Christianisation, or conversion of the empire to Christianity, a gradual process that lasted from the 2nd to the 5th centuries.[30][31]
+
+In 376, the Goths, fleeing from the Huns, received permission from Emperor Valens (r. 364–378) to settle in the Roman province of Thracia in the Balkans. The settlement did not go smoothly, and when Roman officials mishandled the situation, the Goths began to raid and plunder.[E] Valens, attempting to put down the disorder, was killed fighting the Goths at the Battle of Adrianople on 9 August 378.[33] As well as the threat from such tribal confederacies from the north, internal divisions within the empire, especially within the Christian Church, caused problems.[34] In 400, the Visigoths invaded the Western Roman Empire and, although briefly forced back from Italy, in 410 sacked the city of Rome.[35] In 406 the Alans, Vandals, and Suevi crossed into Gaul; over the next three years they spread across Gaul and in 409 crossed the Pyrenees Mountains into modern-day Spain.[36] The Migration Period began, when various peoples, initially largely Germanic peoples, moved across Europe. The Franks, Alemanni, and the Burgundians all ended up in northern Gaul while the Angles, Saxons, and Jutes settled in Britain,[37] and the Vandals went on to cross the strait of Gibraltar after which they conquered the province of Africa.[38] In the 430s the Huns began invading the empire; their king Attila (r. 434–453) led invasions into the Balkans in 442 and 447, Gaul in 451, and Italy in 452.[39] The Hunnic threat remained until Attila's death in 453, when the Hunnic confederation he led fell apart.[40] These invasions by the tribes completely changed the political and demographic nature of what had been the Western Roman Empire.[37]
+
+By the end of the 5th century the western section of the empire was divided into smaller political units, ruled by the tribes that had invaded in the early part of the century.[41] The deposition of the last emperor of the west, Romulus Augustulus, in 476 has traditionally marked the end of the Western Roman Empire.[13][F] By 493 the Italian peninsula was conquered by the Ostrogoths.[42] The Eastern Roman Empire, often referred to as the Byzantine Empire after the fall of its western counterpart, had little ability to assert control over the lost western territories. The Byzantine emperors maintained a claim over the territory, but while none of the new kings in the west dared to elevate himself to the position of emperor of the west, Byzantine control of most of the Western Empire could not be sustained; the reconquest of the Mediterranean periphery and the Italian Peninsula (Gothic War) in the reign of Justinian (r. 527–565) was the sole, and temporary, exception.[43]
+
+The political structure of Western Europe changed with the end of the united Roman Empire. Although the movements of peoples during this period are usually described as "invasions", they were not just military expeditions but migrations of entire peoples into the empire. Such movements were aided by the refusal of the Western Roman elites to support the army or pay the taxes that would have allowed the military to suppress the migration.[44] The emperors of the 5th century were often controlled by military strongmen such as Stilicho (d. 408), Aetius (d. 454), Aspar (d. 471), Ricimer (d. 472), or Gundobad (d. 516), who were partly or fully of non-Roman background. When the line of Western emperors ceased, many of the kings who replaced them were from the same background. Intermarriage between the new kings and the Roman elites was common.[45] This led to a fusion of Roman culture with the customs of the invading tribes, including the popular assemblies that allowed free male tribal members more say in political matters than was common in the Roman state.[46] Material artefacts left by the Romans and the invaders are often similar, and tribal items were often modelled on Roman objects.[47] Much of the scholarly and written culture of the new kingdoms was also based on Roman intellectual traditions.[48] An important difference was the gradual loss of tax revenue by the new polities. Many of the new political entities no longer supported their armies through taxes, instead relying on granting them land or rents. This meant there was less need for large tax revenues and so the taxation systems decayed.[49] Warfare was common between and within the kingdoms. Slavery declined as the supply weakened, and society became more rural.[50][G]
+
+Between the 5th and 8th centuries, new peoples and individuals filled the political void left by Roman centralised government.[48] The Ostrogoths, a Gothic tribe, settled in Roman Italy in the late fifth century under Theoderic the Great (d. 526) and set up a kingdom marked by its co-operation between the Italians and the Ostrogoths, at least until the last years of Theodoric's reign.[52] The Burgundians settled in Gaul, and after an earlier realm was destroyed by the Huns in 436 formed a new kingdom in the 440s. Between today's Geneva and Lyon, it grew to become the realm of Burgundy in the late 5th and early 6th centuries.[53] Elsewhere in Gaul, the Franks and Celtic Britons set up small polities. Francia was centred in northern Gaul, and the first king of whom much is known is Childeric I (d. 481). His grave was discovered in 1653 and is remarkable for its grave goods, which included weapons and a large quantity of gold.[54]
+
+Under Childeric's son Clovis I (r. 509–511), the founder of the Merovingian dynasty, the Frankish kingdom expanded and converted to Christianity. The Britons, related to the natives of Britannia – modern-day Great Britain – settled in what is now Brittany.[55][H] Other monarchies were established by the Visigothic Kingdom in the Iberian Peninsula, the Suebi in northwestern Iberia, and the Vandal Kingdom in North Africa.[53] In the sixth century, the Lombards settled in Northern Italy, replacing the Ostrogothic kingdom with a grouping of duchies that occasionally selected a king to rule over them all. By the late sixth century, this arrangement had been replaced by a permanent monarchy, the Kingdom of the Lombards.[56]
+
+The invasions brought new ethnic groups to Europe, although some regions received a larger influx of new peoples than others. In Gaul for instance, the invaders settled much more extensively in the north-east than in the south-west. Slavs settled in Central and Eastern Europe and the Balkan Peninsula. The settlement of peoples was accompanied by changes in languages. Latin, the literary language of the Western Roman Empire, was gradually replaced by vernacular languages which evolved from Latin, but were distinct from it, collectively known as Romance languages. These changes from Latin to the new languages took many centuries. Greek remained the language of the Byzantine Empire, but the migrations of the Slavs added Slavic languages to Eastern Europe.[57]
+
+As Western Europe witnessed the formation of new kingdoms, the Eastern Roman Empire remained intact and experienced an economic revival that lasted into the early 7th century. There were fewer invasions of the eastern section of the empire; most occurred in the Balkans. Peace with the Sasanian Empire, the traditional enemy of Rome, lasted throughout most of the 5th century. The Eastern Empire was marked by closer relations between the political state and Christian Church, with doctrinal matters assuming an importance in Eastern politics that they did not have in Western Europe. Legal developments included the codification of Roman law; the first effort—the Codex Theodosianus—was completed in 438.[59] Under Emperor Justinian (r. 527–565), another compilation took place—the Corpus Juris Civilis.[60] Justinian also oversaw the construction of the Hagia Sophia in Constantinople and the reconquest of North Africa from the Vandals and Italy from the Ostrogoths,[61] under Belisarius (d. 565).[62] The conquest of Italy was not complete, as a deadly outbreak of plague in 542 led to the rest of Justinian's reign concentrating on defensive measures rather than further conquests.[61]
+
+At the Emperor's death, the Byzantines had control of most of Italy, North Africa, and a small foothold in southern Spain. Justinian's reconquests have been criticised by historians for overextending his realm and setting the stage for the early Muslim conquests, but many of the difficulties faced by Justinian's successors were due not just to over-taxation to pay for his wars but to the essentially civilian nature of the empire, which made raising troops difficult.[63]
+
+In the Eastern Empire the slow infiltration of the Balkans by the Slavs added a further difficulty for Justinian's successors. It began gradually, but by the late 540s Slavic tribes were in Thrace and Illyrium, and had defeated an imperial army near Adrianople in 551. In the 560s the Avars began to expand from their base on the north bank of the Danube; by the end of the 6th-century, they were the dominant power in Central Europe and routinely able to force the Eastern emperors to pay tribute. They remained a strong power until 796.[64]
+
+An additional problem to face the empire came as a result of the involvement of Emperor Maurice (r. 582–602) in Persian politics when he intervened in a succession dispute. This led to a period of peace, but when Maurice was overthrown, the Persians invaded and during the reign of Emperor Heraclius (r. 610–641) controlled large chunks of the empire, including Egypt, Syria, and Anatolia until Heraclius' successful counterattack. In 628 the empire secured a peace treaty and recovered all of its lost territories.[65]
+
+In Western Europe, some of the older Roman elite families died out while others became more involved with ecclesiastical than secular affairs. Values attached to Latin scholarship and education mostly disappeared, and while literacy remained important, it became a practical skill rather than a sign of elite status. In the 4th century, Jerome (d. 420) dreamed that God rebuked him for spending more time reading Cicero than the Bible. By the 6th century, Gregory of Tours (d. 594) had a similar dream, but instead of being chastised for reading Cicero, he was chastised for learning shorthand.[66] By the late 6th century, the principal means of religious instruction in the Church had become music and art rather than the book.[67] Most intellectual efforts went towards imitating classical scholarship, but some original works were created, along with now-lost oral compositions. The writings of Sidonius Apollinaris (d. 489), Cassiodorus (d. c. 585), and Boethius (d. c. 525) were typical of the age.[68]
+
+Changes also took place among laymen, as aristocratic culture focused on great feasts held in halls rather than on literary pursuits. Clothing for the elites was richly embellished with jewels and gold. Lords and kings supported entourages of fighters who formed the backbone of the military forces.[I] Family ties within the elites were important, as were the virtues of loyalty, courage, and honour. These ties led to the prevalence of the feud in aristocratic society, examples of which included those related by Gregory of Tours that took place in Merovingian Gaul. Most feuds seem to have ended quickly with the payment of some sort of compensation.[71] Women took part in aristocratic society mainly in their roles as wives and mothers of men, with the role of mother of a ruler being especially prominent in Merovingian Gaul. In Anglo-Saxon society the lack of many child rulers meant a lesser role for women as queen mothers, but this was compensated for by the increased role played by abbesses of monasteries. Only in Italy does it appear that women were always considered under the protection and control of a male relative.[72]
+
+Peasant society is much less documented than the nobility. Most of the surviving information available to historians comes from archaeology; few detailed written records documenting peasant life remain from before the 9th century. Most of the descriptions of the lower classes come from either law codes or writers from the upper classes.[73] Landholding patterns in the West were not uniform; some areas had greatly fragmented landholding patterns, but in other areas large contiguous blocks of land were the norm. These differences allowed for a wide variety of peasant societies, some dominated by aristocratic landholders and others having a great deal of autonomy.[74] Land settlement also varied greatly. Some peasants lived in large settlements that numbered as many as 700 inhabitants. Others lived in small groups of a few families and still others lived on isolated farms spread over the countryside. There were also areas where the pattern was a mix of two or more of those systems.[75] Unlike in the late Roman period, there was no sharp break between the legal status of the free peasant and the aristocrat, and it was possible for a free peasant's family to rise into the aristocracy over several generations through military service to a powerful lord.[76]
+
+Roman city life and culture changed greatly in the early Middle Ages. Although Italian cities remained inhabited, they contracted significantly in size. Rome, for instance, shrank from a population of hundreds of thousands to around 30,000 by the end of the 6th century. Roman temples were converted into Christian churches and city walls remained in use.[77] In Northern Europe, cities also shrank, while civic monuments and other public buildings were raided for building materials. The establishment of new kingdoms often meant some growth for the towns chosen as capitals.[78] Although there had been Jewish communities in many Roman cities, the Jews suffered periods of persecution after the conversion of the empire to Christianity. Officially they were tolerated, if subject to conversion efforts, and at times were even encouraged to settle in new areas.[79]
+
+Religious beliefs in the Eastern Empire and Iran were in flux during the late sixth and early seventh centuries. Judaism was an active proselytising faith, and at least one Arab political leader converted to it.[J] Christianity had active missions competing with the Persians' Zoroastrianism in seeking converts, especially among residents of the Arabian Peninsula. All these strands came together with the emergence of Islam in Arabia during the lifetime of Muhammad (d. 632).[81] After his death, Islamic forces conquered much of the Eastern Empire and Persia, starting with Syria in 634–635, continuing with Persia between 637 and 642, reaching Egypt in 640–641, North Africa in the later seventh century, and the Iberian Peninsula in 711.[82] By 714, Islamic forces controlled much of the peninsula in a region they called Al-Andalus.[83]
+
+The Islamic conquests reached their peak in the mid-eighth century. The defeat of Muslim forces at the Battle of Tours in 732 led to the reconquest of southern France by the Franks, but the main reason for the halt of Islamic growth in Europe was the overthrow of the Umayyad Caliphate and its replacement by the Abbasid Caliphate. The Abbasids moved their capital to Baghdad and were more concerned with the Middle East than Europe, losing control of sections of the Muslim lands. Umayyad descendants took over the Iberian Peninsula, the Aghlabids controlled North Africa, and the Tulunids became rulers of Egypt.[84] By the middle of the 8th century, new trading patterns were emerging in the Mediterranean; trade between the Franks and the Arabs replaced the old Roman economy. Franks traded timber, furs, swords and slaves in return for silks and other fabrics, spices, and precious metals from the Arabs.[85]
+
+The migrations and invasions of the 4th and 5th centuries disrupted trade networks around the Mediterranean. African goods stopped being imported into Europe, first disappearing from the interior and by the 7th century found only in a few cities such as Rome or Naples. By the end of the 7th century, under the impact of the Muslim conquests, African products were no longer found in Western Europe. The replacement of goods from long-range trade with local products was a trend throughout the old Roman lands that happened in the Early Middle Ages. This was especially marked in the lands that did not lie on the Mediterranean, such as northern Gaul or Britain. Non-local goods appearing in the archaeological record are usually luxury goods. In the northern parts of Europe, not only were the trade networks local, but the goods carried were simple, with little pottery or other complex products. Around the Mediterranean, pottery remained prevalent and appears to have been traded over medium-range networks, not just produced locally.[86]
+
+The various Germanic states in the west all had coinages that imitated existing Roman and Byzantine forms. Gold continued to be minted until the end of the 7th century in 693-94 when it was replaced by silver in the Merovingian kindgon. The basic Frankish silver coin was the denarius or denier, while the Anglo-Saxon version was called a penny. From these areas, the denier or penny spread throughout Europe from 700 to 1000 AD. Copper or bronze coins were not struck, nor were gold except in Southern Europe. No silver coins denominated in multiple units were minted.[87]
+
+Christianity was a major unifying factor between Eastern and Western Europe before the Arab conquests, but the conquest of North Africa sundered maritime connections between those areas. Increasingly, the Byzantine Church differed in language, practices, and liturgy from the Western Church. The Eastern Church used Greek instead of the Western Latin. Theological and political differences emerged, and by the early and middle 8th century issues such as iconoclasm, clerical marriage, and state control of the Church had widened to the extent that the cultural and religious differences were greater than the similarities.[88] The formal break, known as the East–West Schism, came in 1054, when the papacy and the patriarchy of Constantinople clashed over papal supremacy and excommunicated each other, which led to the division of Christianity into two Churches—the Western branch became the Roman Catholic Church and the Eastern branch the Eastern Orthodox Church.[89]
+
+The ecclesiastical structure of the Roman Empire survived the movements and invasions in the west mostly intact, but the papacy was little regarded, and few of the Western bishops looked to the bishop of Rome for religious or political leadership. Many of the popes prior to 750 were more concerned with Byzantine affairs and Eastern theological controversies. The register, or archived copies of the letters, of Pope Gregory the Great (pope 590–604) survived, and of those more than 850 letters, the vast majority were concerned with affairs in Italy or Constantinople. The only part of Western Europe where the papacy had influence was Britain, where Gregory had sent the Gregorian mission in 597 to convert the Anglo-Saxons to Christianity.[90] Irish missionaries were most active in Western Europe between the 5th and the 7th centuries, going first to England and Scotland and then on to the continent. Under such monks as Columba (d. 597) and Columbanus (d. 615), they founded monasteries, taught in Latin and Greek, and authored secular and religious works.[91]
+
+The Early Middle Ages witnessed the rise of monasticism in the West. The shape of European monasticism was determined by traditions and ideas that originated with the Desert Fathers of Egypt and Syria. Most European monasteries were of the type that focuses on community experience of the spiritual life, called cenobitism, which was pioneered by Pachomius (d. 348) in the 4th century. Monastic ideals spread from Egypt to Western Europe in the 5th and 6th centuries through hagiographical literature such as the Life of Anthony.[92] Benedict of Nursia (d. 547) wrote the Benedictine Rule for Western monasticism during the 6th century, detailing the administrative and spiritual responsibilities of a community of monks led by an abbot.[93] Monks and monasteries had a deep effect on the religious and political life of the Early Middle Ages, in various cases acting as land trusts for powerful families, centres of propaganda and royal support in newly conquered regions, and bases for missions and proselytisation.[94] They were the main and sometimes only outposts of education and literacy in a region. Many of the surviving manuscripts of the Latin classics were copied in monasteries in the Early Middle Ages.[95] Monks were also the authors of new works, including history, theology, and other subjects, written by authors such as Bede (d. 735), a native of northern England who wrote in the late 7th and early 8th centuries.[96]
+
+The Frankish kingdom in northern Gaul split into kingdoms called Austrasia, Neustria, and Burgundy during the 6th and 7th centuries, all of them ruled by the Merovingian dynasty, who were descended from Clovis. The 7th century was a tumultuous period of wars between Austrasia and Neustria.[97] Such warfare was exploited by Pippin (d. 640), the Mayor of the Palace for Austrasia who became the power behind the Austrasian throne. Later members of his family inherited the office, acting as advisers and regents. One of his descendants, Charles Martel (d. 741), won the Battle of Poitiers in 732, halting the advance of Muslim armies across the Pyrenees.[98][K] Great Britain was divided into small states dominated by the kingdoms of Northumbria, Mercia, Wessex, and East Anglia which descended from the Anglo-Saxon invaders. Smaller kingdoms in present-day Wales and Scotland were still under the control of the native Britons and Picts.[100] Ireland was divided into even smaller political units, usually known as tribal kingdoms, under the control of kings. There were perhaps as many as 150 local kings in Ireland, of varying importance.[101]
+
+The Carolingian dynasty, as the successors to Charles Martel are known, officially took control of the kingdoms of Austrasia and Neustria in a coup of 753 led by Pippin III (r. 752–768). A contemporary chronicle claims that Pippin sought, and gained, authority for this coup from Pope Stephen II (pope 752–757). Pippin's takeover was reinforced with propaganda that portrayed the Merovingians as inept or cruel rulers, exalted the accomplishments of Charles Martel, and circulated stories of the family's great piety. At the time of his death in 768, Pippin left his kingdom in the hands of his two sons, Charles (r. 768–814) and Carloman (r. 768–771). When Carloman died of natural causes, Charles blocked the succession of Carloman's young son and installed himself as the king of the united Austrasia and Neustria. Charles, more often known as Charles the Great or Charlemagne, embarked upon a programme of systematic expansion in 774 that unified a large portion of Europe, eventually controlling modern-day France, northern Italy, and Saxony. In the wars that lasted beyond 800, he rewarded allies with war booty and command over parcels of land.[102] In 774, Charlemagne conquered the Lombards, which freed the papacy from the fear of Lombard conquest and marked the beginnings of the Papal States.[103][L]
+
+The coronation of Charlemagne as emperor on Christmas Day 800 is regarded as a turning point in medieval history, marking a return of the Western Roman Empire, since the new emperor ruled over much of the area previously controlled by the Western emperors.[106] It also marks a change in Charlemagne's relationship with the Byzantine Empire, as the assumption of the imperial title by the Carolingians asserted their equivalence to the Byzantine state.[107] There were several differences between the newly established Carolingian Empire and both the older Western Roman Empire and the concurrent Byzantine Empire. The Frankish lands were rural in character, with only a few small cities. Most of the people were peasants settled on small farms. Little trade existed and much of that was with the British Isles and Scandinavia, in contrast to the older Roman Empire with its trading networks centred on the Mediterranean.[106] The empire was administered by an itinerant court that travelled with the emperor, as well as approximately 300 imperial officials called counts, who administered the counties the empire had been divided into. Clergy and local bishops served as officials, as well as the imperial officials called missi dominici, who served as roving inspectors and troubleshooters.[108]
+
+Charlemagne's court in Aachen was the centre of the cultural revival sometimes referred to as the "Carolingian Renaissance". Literacy increased, as did development in the arts, architecture and jurisprudence, as well as liturgical and scriptural studies. The English monk Alcuin (d. 804) was invited to Aachen and brought the education available in the monasteries of Northumbria. Charlemagne's chancery—or writing office—made use of a new script today known as Carolingian minuscule,[M] allowing a common writing style that advanced communication across much of Europe. Charlemagne sponsored changes in church liturgy, imposing the Roman form of church service on his domains, as well as the Gregorian chant in liturgical music for the churches. An important activity for scholars during this period was the copying, correcting, and dissemination of basic works on religious and secular topics, with the aim of encouraging learning. New works on religious topics and schoolbooks were also produced.[110] Grammarians of the period modified the Latin language, changing it from the Classical Latin of the Roman Empire into a more flexible form to fit the needs of the Church and government. By the reign of Charlemagne, the language had so diverged from the classical Latin that it was later called Medieval Latin.[111]
+
+Charlemagne planned to continue the Frankish tradition of dividing his kingdom between all his heirs, but was unable to do so as only one son, Louis the Pious (r. 814–840), was still alive by 813. Just before Charlemagne died in 814, he crowned Louis as his successor. Louis's reign of 26 years was marked by numerous divisions of the empire among his sons and, after 829, civil wars between various alliances of father and sons over the control of various parts of the empire. Eventually, Louis recognised his eldest son Lothair I (d. 855) as emperor and gave him Italy.[N] Louis divided the rest of the empire between Lothair and Charles the Bald (d. 877), his youngest son. Lothair took East Francia, comprising both banks of the Rhine and eastwards, leaving Charles West Francia with the empire to the west of the Rhineland and the Alps. Louis the German (d. 876), the middle child, who had been rebellious to the last, was allowed to keep Bavaria under the suzerainty of his elder brother. The division was disputed. Pepin II of Aquitaine (d. after 864), the emperor's grandson, rebelled in a contest for Aquitaine, while Louis the German tried to annex all of East Francia. Louis the Pious died in 840, with the empire still in chaos.[113]
+
+A three-year civil war followed his death. By the Treaty of Verdun (843), a kingdom between the Rhine and Rhone rivers was created for Lothair to go with his lands in Italy, and his imperial title was recognised. Louis the German was in control of Bavaria and the eastern lands in modern-day Germany. Charles the Bald received the western Frankish lands, comprising most of modern-day France.[113] Charlemagne's grandsons and great-grandsons divided their kingdoms between their descendants, eventually causing all internal cohesion to be lost.[114][O] In 987 the Carolingian dynasty was replaced in the western lands, with the crowning of Hugh Capet (r. 987–996) as king.[P][Q] In the eastern lands the dynasty had died out earlier, in 911, with the death of Louis the Child,[117] and the selection of the unrelated Conrad I (r. 911–918) as king.[118]
+
+The breakup of the Carolingian Empire was accompanied by invasions, migrations, and raids by external foes. The Atlantic and northern shores were harassed by the Vikings, who also raided the British Isles and settled there as well as in Iceland. In 911, the Viking chieftain Rollo (d. c. 931) received permission from the Frankish King Charles the Simple (r. 898–922) to settle in what became Normandy.[119][R] The eastern parts of the Frankish kingdoms, especially Germany and Italy, were under continual Magyar assault until the invader's defeat at the Battle of Lechfeld in 955.[121] The breakup of the Abbasid dynasty meant that the Islamic world fragmented into smaller political states, some of which began expanding into Italy and Sicily, as well as over the Pyrenees into the southern parts of the Frankish kingdoms.[122]
+
+Efforts by local kings to fight the invaders led to the formation of new political entities. In Anglo-Saxon England, King Alfred the Great (r. 871–899) came to an agreement with the Viking invaders in the late 9th century, resulting in Danish settlements in Northumbria, Mercia, and parts of East Anglia.[123] By the middle of the 10th century, Alfred's successors had conquered Northumbria, and restored English control over most of the southern part of Great Britain.[124] In northern Britain, Kenneth MacAlpin (d. c. 860) united the Picts and the Scots into the Kingdom of Alba.[125] In the early 10th century, the Ottonian dynasty had established itself in Germany, and was engaged in driving back the Magyars. Its efforts culminated in the coronation in 962 of Otto I (r. 936–973) as Holy Roman Emperor.[126] In 972, he secured recognition of his title by the Byzantine Empire, which he sealed with the marriage of his son Otto II (r. 967–983) to Theophanu (d. 991), daughter of an earlier Byzantine Emperor Romanos II (r. 959–963).[127] By the late 10th century Italy had been drawn into the Ottonian sphere after a period of instability;[128] Otto III (r. 996–1002) spent much of his later reign in the kingdom.[129] The western Frankish kingdom was more fragmented, and although kings remained nominally in charge, much of the political power devolved to the local lords.[130]
+
+Missionary efforts to Scandinavia during the 9th and 10th centuries helped strengthen the growth of kingdoms such as Sweden, Denmark, and Norway, which gained power and territory. Some kings converted to Christianity, although not all by 1000. Scandinavians also expanded and colonised throughout Europe. Besides the settlements in Ireland, England, and Normandy, further settlement took place in what became Russia and Iceland. Swedish traders and raiders ranged down the rivers of the Russian steppe, and even attempted to seize Constantinople in 860 and 907.[131] Christian Spain, initially driven into a small section of the peninsula in the north, expanded slowly south during the 9th and 10th centuries, establishing the kingdoms of Asturias and León.[132]
+
+In Eastern Europe, Byzantium revived its fortunes under Emperor Basil I (r. 867–886) and his successors Leo VI (r. 886–912) and Constantine VII (r. 913–959), members of the Macedonian dynasty. Commerce revived and the emperors oversaw the extension of a uniform administration to all the provinces. The military was reorganised, which allowed the emperors John I (r. 969–976) and Basil II (r. 976–1025) to expand the frontiers of the empire on all fronts. The imperial court was the centre of a revival of classical learning, a process known as the Macedonian Renaissance. Writers such as John Geometres (fl. early 10th century) composed new hymns, poems, and other works.[133] Missionary efforts by both Eastern and Western clergy resulted in the conversion of the Moravians, Bulgars, Bohemians, Poles, Magyars, and Slavic inhabitants of the Kievan Rus'. These conversions contributed to the founding of political states in the lands of those peoples—the states of Moravia, Bulgaria, Bohemia, Poland, Hungary, and the Kievan Rus'.[134] Bulgaria, which was founded around 680, at its height reached from Budapest to the Black Sea and from the Dnieper River in modern Ukraine to the Adriatic Sea.[135] By 1018, the last Bulgarian nobles had surrendered to the Byzantine Empire.[136]
+
+Few large stone buildings were constructed between the Constantinian basilicas of the 4th century and the 8th century, although many smaller ones were built during the 6th and 7th centuries. By the beginning of the 8th century, the Carolingian Empire revived the basilica form of architecture.[138] One feature of the basilica is the use of a transept,[139] or the "arms" of a cross-shaped building that are perpendicular to the long nave.[140] Other new features of religious architecture include the crossing tower and a monumental entrance to the church, usually at the west end of the building.[141]
+
+Carolingian art was produced for a small group of figures around the court, and the monasteries and churches they supported. It was dominated by efforts to regain the dignity and classicism of imperial Roman and Byzantine art, but was also influenced by the Insular art of the British Isles. Insular art integrated the energy of Irish Celtic and Anglo-Saxon Germanic styles of ornament with Mediterranean forms such as the book, and established many characteristics of art for the rest of the medieval period. Surviving religious works from the Early Middle Ages are mostly illuminated manuscripts and carved ivories, originally made for metalwork that has since been melted down.[142][143] Objects in precious metals were the most prestigious form of art, but almost all are lost except for a few crosses such as the Cross of Lothair, several reliquaries, and finds such as the Anglo-Saxon burial at Sutton Hoo and the hoards of Gourdon from Merovingian France, Guarrazar from Visigothic Spain and Nagyszentmiklós near Byzantine territory. There are survivals from the large brooches in fibula or penannular form that were a key piece of personal adornment for elites, including the Irish Tara Brooch.[144] Highly decorated books were mostly Gospel Books and these have survived in larger numbers, including the Insular Book of Kells, the Book of Lindisfarne, and the imperial Codex Aureus of St. Emmeram, which is one of the few to retain its "treasure binding" of gold encrusted with jewels.[145] Charlemagne's court seems to have been responsible for the acceptance of figurative monumental sculpture in Christian art,[146] and by the end of the period near life-sized figures such as the Gero Cross were common in important churches.[147]
+
+During the later Roman Empire, the principal military developments were attempts to create an effective cavalry force as well as the continued development of highly specialised types of troops. The creation of heavily armoured cataphract-type soldiers as cavalry was an important feature of the 5th-century Roman military. The various invading tribes had differing emphases on types of soldiers—ranging from the primarily infantry Anglo-Saxon invaders of Britain to the Vandals and Visigoths who had a high proportion of cavalry in their armies.[148] During the early invasion period, the stirrup had not been introduced into warfare, which limited the usefulness of cavalry as shock troops because it was not possible to put the full force of the horse and rider behind blows struck by the rider.[149] The greatest change in military affairs during the invasion period was the adoption of the Hunnic composite bow in place of the earlier, and weaker, Scythian composite bow.[150] Another development was the increasing use of longswords[151] and the progressive replacement of scale armour by mail armour and lamellar armour.[152]
+
+The importance of infantry and light cavalry began to decline during the early Carolingian period, with a growing dominance of elite heavy cavalry. The use of militia-type levies of the free population declined over the Carolingian period.[153] Although much of the Carolingian armies were mounted, a large proportion during the early period appear to have been mounted infantry, rather than true cavalry.[154] One exception was Anglo-Saxon England, where the armies were still composed of regional levies, known as the fyrd, which were led by the local elites.[155] In military technology, one of the main changes was the return of the crossbow, which had been known in Roman times and reappeared as a military weapon during the last part of the Early Middle Ages.[156] Another change was the introduction of the stirrup, which increased the effectiveness of cavalry as shock troops. A technological advance that had implications beyond the military was the horseshoe, which allowed horses to be used in rocky terrain.[157]
+
+The High Middle Ages was a period of tremendous expansion of population. The estimated population of Europe grew from 35 to 80 million between 1000 and 1347, although the exact causes remain unclear: improved agricultural techniques, the decline of slaveholding, a more clement climate and the lack of invasion have all been suggested.[160][161] As much as 90 per cent of the European population remained rural peasants. Many were no longer settled in isolated farms but had gathered into small communities, usually known as manors or villages.[161] These peasants were often subject to noble overlords and owed them rents and other services, in a system known as manorialism. There remained a few free peasants throughout this period and beyond,[162] with more of them in the regions of Southern Europe than in the north. The practice of assarting, or bringing new lands into production by offering incentives to the peasants who settled them, also contributed to the expansion of population.[163]
+
+The open-field system of agriculture was commonly practiced in most of Europe, especially in "northwestern and central Europe".[164] Such agricultural communities had three basic characteristics: individual peasant holdings in the form of strips of land were scattered among the different fields belonging to the manor; crops were rotated from year to year to preserve soil fertility; and common land was used for grazing livestock and other purposes. Some regions used a three-field system of crop rotation, others retained the older two-field system.[165]
+
+Other sections of society included the nobility, clergy, and townsmen. Nobles, both the titled nobility and simple knights, exploited the manors and the peasants, although they did not own lands outright but were granted rights to the income from a manor or other lands by an overlord through the system of feudalism. During the 11th and 12th centuries, these lands, or fiefs, came to be considered hereditary, and in most areas they were no longer divisible between all the heirs as had been the case in the early medieval period. Instead, most fiefs and lands went to the eldest son.[166][S] The dominance of the nobility was built upon its control of the land, its military service as heavy cavalry, control of castles, and various immunities from taxes or other impositions.[T] Castles, initially in wood but later in stone, began to be constructed in the 9th and 10th centuries in response to the disorder of the time, and provided protection from invaders as well as allowing lords defence from rivals. Control of castles allowed the nobles to defy kings or other overlords.[168] Nobles were stratified; kings and the highest-ranking nobility controlled large numbers of commoners and large tracts of land, as well as other nobles. Beneath them, lesser nobles had authority over smaller areas of land and fewer people. Knights were the lowest level of nobility; they controlled but did not own land, and had to serve other nobles.[169][U]
+
+The clergy was divided into two types: the secular clergy, who lived out in the world, and the regular clergy, who lived isolated under a religious rule and usually consisted of monks.[171] Throughout the period monks remained a very small proportion of the population, usually less than one percent.[172] Most of the regular clergy were drawn from the nobility, the same social class that served as the recruiting ground for the upper levels of the secular clergy. The local parish priests were often drawn from the peasant class.[173] Townsmen were in a somewhat unusual position, as they did not fit into the traditional three-fold division of society into nobles, clergy, and peasants. During the 12th and 13th centuries, the ranks of the townsmen expanded greatly as existing towns grew and new population centres were founded.[174] But throughout the Middle Ages the population of the towns probably never exceeded 10 percent of the total population.[175]
+
+Jews also spread across Europe during the period. Communities were established in Germany and England in the 11th and 12th centuries, but Spanish Jews, long settled in Spain under the Muslims, came under Christian rule and increasing pressure to convert to Christianity.[79] Most Jews were confined to the cities, as they were not allowed to own land or be peasants.[176][V] Besides the Jews, there were other non-Christians on the edges of Europe—pagan Slavs in Eastern Europe and Muslims in Southern Europe.[177]
+
+Women in the Middle Ages were officially required to be subordinate to some male, whether their father, husband, or other kinsman. Widows, who were often allowed much control over their own lives, were still restricted legally. Women's work generally consisted of household or other domestically inclined tasks. Peasant women were usually responsible for taking care of the household, child-care, as well as gardening and animal husbandry near the house. They could supplement the household income by spinning or brewing at home. At harvest-time, they were also expected to help with field-work.[178] Townswomen, like peasant women, were responsible for the household, and could also engage in trade. What trades were open to women varied by country and period.[179] Noblewomen were responsible for running a household, and could occasionally be expected to handle estates in the absence of male relatives, but they were usually restricted from participation in military or government affairs. The only role open to women in the Church was that of nuns, as they were unable to become priests.[178]
+
+In central and northern Italy and in Flanders, the rise of towns that were to a degree self-governing stimulated economic growth and created an environment for new types of trade associations. Commercial cities on the shores of the Baltic entered into agreements known as the Hanseatic League, and the Italian Maritime republics such as Venice, Genoa, and Pisa expanded their trade throughout the Mediterranean.[W] Great trading fairs were established and flourished in northern France during the period, allowing Italian and German merchants to trade with each other as well as local merchants.[181] In the late 13th century new land and sea routes to the Far East were pioneered, famously described in The Travels of Marco Polo written by one of the traders, Marco Polo (d. 1324).[182] Besides new trading opportunities, agricultural and technological improvements enabled an increase in crop yields, which in turn allowed the trade networks to expand.[183] Rising trade brought new methods of dealing with money, and gold coinage was again minted in Europe, first in Italy and later in France and other countries. New forms of commercial contracts emerged, allowing risk to be shared among merchants. Accounting methods improved, partly through the use of double-entry bookkeeping; letters of credit also appeared, allowing easy transmission of money.[184]
+
+The High Middle Ages was the formative period in the history of the modern Western state. Kings in France, England, and Spain consolidated their power, and set up lasting governing institutions.[185] New kingdoms such as Hungary and Poland, after their conversion to Christianity, became Central European powers.[186] The Magyars settled Hungary around 900 under King Árpád (d. c. 907) after a series of invasions in the 9th century.[187] The papacy, long attached to an ideology of independence from secular kings, first asserted its claim to temporal authority over the entire Christian world; the Papal Monarchy reached its apogee in the early 13th century under the pontificate of Innocent III (pope 1198–1216).[188] Northern Crusades and the advance of Christian kingdoms and military orders into previously pagan regions in the Baltic and Finnic north-east brought the forced assimilation of numerous native peoples into European culture.[189]
+
+During the early High Middle Ages, Germany was ruled by the Ottonian dynasty, which struggled to control the powerful dukes ruling over territorial duchies tracing back to the Migration period. In 1024, they were replaced by the Salian dynasty, who famously clashed with the papacy under Emperor Henry IV (r. 1084–1105) over Church appointments as part of the Investiture Controversy.[190] His successors continued to struggle against the papacy as well as the German nobility. A period of instability followed the death of Emperor Henry V (r. 1111–25), who died without heirs, until Frederick I Barbarossa (r. 1155–90) took the imperial throne.[191] Although he ruled effectively, the basic problems remained, and his successors continued to struggle into the 13th century.[192] Barbarossa's grandson Frederick II (r. 1220–1250), who was also heir to the throne of Sicily through his mother, clashed repeatedly with the papacy. His court was famous for its scholars and he was often accused of heresy.[193] He and his successors faced many difficulties, including the invasion of the Mongols into Europe in the mid-13th century. Mongols first shattered the Kievan Rus' principalities and then invaded Eastern Europe in 1241, 1259, and 1287.[194]
+
+Under the Capetian dynasty the French monarchy slowly began to expand its authority over the nobility, growing out of the Île-de-France to exert control over more of the country in the 11th and 12th centuries.[195] They faced a powerful rival in the Dukes of Normandy, who in 1066 under William the Conqueror (duke 1035–1087), conquered England (r. 1066–87) and created a cross-channel empire that lasted, in various forms, throughout the rest of the Middle Ages.[196][197] Normans also settled in Sicily and southern Italy, when Robert Guiscard (d. 1085) landed there in 1059 and established a duchy that later became the Kingdom of Sicily.[198] Under the Angevin dynasty of Henry II (r. 1154–89) and his son Richard I (r. 1189–99), the kings of England ruled over England and large areas of France,[199][X] brought to the family by Henry II's marriage to Eleanor of Aquitaine (d. 1204), heiress to much of southern France.[201][Y] Richard's younger brother John (r. 1199–1216) lost Normandy and the rest of the northern French possessions in 1204 to the French King Philip II Augustus (r. 1180–1223). This led to dissension among the English nobility, while John's financial exactions to pay for his unsuccessful attempts to regain Normandy led in 1215 to Magna Carta, a charter that confirmed the rights and privileges of free men in England. Under Henry III (r. 1216–72), John's son, further concessions were made to the nobility, and royal power was diminished.[202] The French monarchy continued to make gains against the nobility during the late 12th and 13th centuries, bringing more territories within the kingdom under the king's personal rule and centralising the royal administration.[203] Under Louis IX (r. 1226–70), royal prestige rose to new heights as Louis served as a mediator for most of Europe.[204][Z]
+
+In Iberia, the Christian states, which had been confined to the north-western part of the peninsula, began to push back against the Islamic states in the south, a period known as the Reconquista.[206] By about 1150, the Christian north had coalesced into the five major kingdoms of León, Castile, Aragon, Navarre, and Portugal.[207] Southern Iberia remained under control of Islamic states, initially under the Caliphate of Córdoba, which broke up in 1031 into a shifting number of petty states known as taifas,[206] who fought with the Christians until the Almohad Caliphate re-established centralised rule over Southern Iberia in the 1170s.[208] Christian forces advanced again in the early 13th century, culminating in the capture of Seville in 1248.[209]
+
+In the 11th century, the Seljuk Turks took over much of the Middle East, occupying Persia during the 1040s, Armenia in the 1060s, and Jerusalem in 1070. In 1071, the Turkish army defeated the Byzantine army at the Battle of Manzikert and captured the Byzantine Emperor Romanus IV (r. 1068–71). The Turks were then free to invade Asia Minor, which dealt a dangerous blow to the Byzantine Empire by seizing a large part of its population and its economic heartland. Although the Byzantines regrouped and recovered somewhat, they never fully regained Asia Minor and were often on the defensive. The Turks also had difficulties, losing control of Jerusalem to the Fatimids of Egypt and suffering from a series of internal civil wars.[211] The Byzantines also faced a revived Bulgaria, which in the late 12th and 13th centuries spread throughout the Balkans.[212]
+
+The crusades were intended to seize Jerusalem from Muslim control. The First Crusade was proclaimed by Pope Urban II (pope 1088–99) at the Council of Clermont in 1095 in response to a request from the Byzantine Emperor Alexios I Komnenos (r. 1081–1118) for aid against further Muslim advances. Urban promised indulgence to anyone who took part. Tens of thousands of people from all levels of society mobilised across Europe and captured Jerusalem in 1099.[213] One feature of the crusades was the pogroms against local Jews that often took place as the crusaders left their countries for the East. These were especially brutal during the First Crusade,[79] when the Jewish communities in Cologne, Mainz, and Worms were destroyed, as well as other communities in cities between the rivers Seine and the Rhine.[214] Another outgrowth of the crusades was the foundation of a new type of monastic order, the military orders of the Templars and Hospitallers, which fused monastic life with military service.[215]
+
+The crusaders consolidated their conquests into crusader states. During the 12th and 13th centuries, there were a series of conflicts between them and the surrounding Islamic states. Appeals from the crusader states to the papacy led to further crusades,[213] such as the Third Crusade, called to try to regain Jerusalem, which had been captured by Saladin (d. 1193) in 1187.[216][AA] In 1203, the Fourth Crusade was diverted from the Holy Land to Constantinople, and captured the city in 1204, setting up a Latin Empire of Constantinople[218] and greatly weakening the Byzantine Empire. The Byzantines recaptured the city in 1261, but never regained their former strength.[219] By 1291 all the crusader states had been captured or forced from the mainland, although a titular Kingdom of Jerusalem survived on the island of Cyprus for several years afterwards.[220]
+
+Popes called for crusades to take place elsewhere besides the Holy Land: in Spain, southern France, and along the Baltic.[213] The Spanish crusades became fused with the Reconquista of Spain from the Muslims. Although the Templars and Hospitallers took part in the Spanish crusades, similar Spanish military religious orders were founded, most of which had become part of the two main orders of Calatrava and Santiago by the beginning of the 12th century.[221] Northern Europe also remained outside Christian influence until the 11th century or later, and became a crusading venue as part of the Northern Crusades of the 12th to 14th centuries. These crusades also spawned a military order, the Order of the Sword Brothers. Another order, the Teutonic Knights, although founded in the crusader states, focused much of its activity in the Baltic after 1225, and in 1309 moved its headquarters to Marienburg in Prussia.[222]
+
+During the 11th century, developments in philosophy and theology led to increased intellectual activity. There was debate between the realists and the nominalists over the concept of "universals". Philosophical discourse was stimulated by the rediscovery of Aristotle and his emphasis on empiricism and rationalism. Scholars such as Peter Abelard (d. 1142) and Peter Lombard (d. 1164) introduced Aristotelian logic into theology. In the late 11th and early 12th centuries cathedral schools spread throughout Western Europe, signalling the shift of learning from monasteries to cathedrals and towns.[223] Cathedral schools were in turn replaced by the universities established in major European cities.[224] Philosophy and theology fused in scholasticism, an attempt by 12th- and 13th-century scholars to reconcile authoritative texts, most notably Aristotle and the Bible. This movement tried to employ a systemic approach to truth and reason[225] and culminated in the thought of Thomas Aquinas (d. 1274), who wrote the Summa Theologica, or Summary of Theology.[226]
+
+Chivalry and the ethos of courtly love developed in royal and noble courts. This culture was expressed in the vernacular languages rather than Latin, and comprised poems, stories, legends, and popular songs spread by troubadours, or wandering minstrels. Often the stories were written down in the chansons de geste, or "songs of great deeds", such as The Song of Roland or The Song of Hildebrand.[227] Secular and religious histories were also produced.[228] Geoffrey of Monmouth (d. c. 1155) composed his Historia Regum Britanniae, a collection of stories and legends about Arthur.[229] Other works were more clearly history, such as Otto von Freising's (d. 1158) Gesta Friderici Imperatoris detailing the deeds of Emperor Frederick Barbarossa, or William of Malmesbury's (d. c. 1143) Gesta Regum on the kings of England.[228]
+
+Legal studies advanced during the 12th century. Both secular law and canon law, or ecclesiastical law, were studied in the High Middle Ages. Secular law, or Roman law, was advanced greatly by the discovery of the Corpus Juris Civilis in the 11th century, and by 1100 Roman law was being taught at Bologna. This led to the recording and standardisation of legal codes throughout Western Europe. Canon law was also studied, and around 1140 a monk named Gratian (fl. 12th century), a teacher at Bologna, wrote what became the standard text of canon law—the Decretum.[230]
+
+Among the results of the Greek and Islamic influence on this period in European history was the replacement of Roman numerals with the decimal positional number system and the invention of algebra, which allowed more advanced mathematics. Astronomy advanced following the translation of Ptolemy's Almagest from Greek into Latin in the late 12th century. Medicine was also studied, especially in southern Italy, where Islamic medicine influenced the school at Salerno.[231]
+
+In the 12th and 13th centuries, Europe experienced economic growth and innovations in methods of production. Major technological advances included the invention of the windmill, the first mechanical clocks, the manufacture of distilled spirits, and the use of the astrolabe.[233] Concave spectacles were invented around 1286 by an unknown Italian artisan, probably working in or near Pisa.[234]
+
+The development of a three-field rotation system for planting crops[161][AB] increased the usage of land from one half in use each year under the old two-field system to two-thirds under the new system, with a consequent increase in production.[235] The development of the heavy plough allowed heavier soils to be farmed more efficiently, aided by the spread of the horse collar, which led to the use of draught horses in place of oxen. Horses are faster than oxen and require less pasture, factors that aided the implementation of the three-field system.[236] Legumes – such as peas, beans, or lentils – were grown more widely as crops, in addition to the usual cereal crops of wheat, oats, barley, and rye.[237]
+
+The construction of cathedrals and castles advanced building technology, leading to the development of large stone buildings. Ancillary structures included new town halls, houses, bridges, and tithe barns.[238] Shipbuilding improved with the use of the rib and plank method rather than the old Roman system of mortise and tenon. Other improvements to ships included the use of lateen sails and the stern-post rudder, both of which increased the speed at which ships could be sailed.[239]
+
+In military affairs, the use of infantry with specialised roles increased. Along with the still-dominant heavy cavalry, armies often included mounted and infantry crossbowmen, as well as sappers and engineers.[240] Crossbows, which had been known in Late Antiquity, increased in use partly because of the increase in siege warfare in the 10th and 11th centuries.[156][AC] The increasing use of crossbows during the 12th and 13th centuries led to the use of closed-face helmets, heavy body armour, as well as horse armour.[242] Gunpowder was known in Europe by the mid-13th century with a recorded use in European warfare by the English against the Scots in 1304, although it was merely used as an explosive and not as a weapon. Cannon were being used for sieges in the 1320s, and hand-held guns were in use by the 1360s.[243]
+
+In the 10th century the establishment of churches and monasteries led to the development of stone architecture that elaborated vernacular Roman forms, from which the term "Romanesque" is derived. Where available, Roman brick and stone buildings were recycled for their materials. From the tentative beginnings known as the First Romanesque, the style flourished and spread across Europe in a remarkably homogeneous form. Just before 1000 there was a great wave of building stone churches all over Europe.[244] Romanesque buildings have massive stone walls, openings topped by semi-circular arches, small windows, and, particularly in France, arched stone vaults.[245] The large portal with coloured sculpture in high relief became a central feature of façades, especially in France, and the capitals of columns were often carved with narrative scenes of imaginative monsters and animals.[246] According to art historian C. R. Dodwell, "virtually all the churches in the West were decorated with wall-paintings", of which few survive.[247] Simultaneous with the development in church architecture, the distinctive European form of the castle was developed and became crucial to politics and warfare.[248]
+
+Romanesque art, especially metalwork, was at its most sophisticated in Mosan art, in which distinct artistic personalities including Nicholas of Verdun (d. 1205) become apparent, and an almost classical style is seen in works such as a font at Liège,[249] contrasting with the writhing animals of the exactly contemporary Gloucester Candlestick. Large illuminated bibles and psalters were the typical forms of luxury manuscripts, and wall-painting flourished in churches, often following a scheme with a Last Judgement on the west wall, a Christ in Majesty at the east end, and narrative biblical scenes down the nave, or in the best surviving example, at Saint-Savin-sur-Gartempe, on the barrel-vaulted roof.[250]
+
+From the early 12th century, French builders developed the Gothic style, marked by the use of rib vaults, pointed arches, flying buttresses, and large stained glass windows. It was used mainly in churches and cathedrals and continued in use until the 16th century in much of Europe. Classic examples of Gothic architecture include Chartres Cathedral and Reims Cathedral in France as well as Salisbury Cathedral in England.[251] Stained glass became a crucial element in the design of churches, which continued to use extensive wall-paintings, now almost all lost.[252]
+
+During this period the practice of manuscript illumination gradually passed from monasteries to lay workshops, so that according to Janetta Benton "by 1300 most monks bought their books in shops",[253] and the book of hours developed as a form of devotional book for lay-people. Metalwork continued to be the most prestigious form of art, with Limoges enamel a popular and relatively affordable option for objects such as reliquaries and crosses.[254] In Italy the innovations of Cimabue and Duccio, followed by the Trecento master Giotto (d. 1337), greatly increased the sophistication and status of panel painting and fresco.[255] Increasing prosperity during the 12th century resulted in greater production of secular art; many carved ivory objects such as gaming-pieces, combs, and small religious figures have survived.[256]
+
+Monastic reform became an important issue during the 11th century, as elites began to worry that monks were not adhering to the rules binding them to a strictly religious life. Cluny Abbey, founded in the Mâcon region of France in 909, was established as part of the Cluniac Reforms, a larger movement of monastic reform in response to this fear.[258] Cluny quickly established a reputation for austerity and rigour. It sought to maintain a high quality of spiritual life by placing itself under the protection of the papacy and by electing its own abbot without interference from laymen, thus maintaining economic and political independence from local lords.[259]
+
+Monastic reform inspired change in the secular Church. The ideals upon which it was based were brought to the papacy by Pope Leo IX (pope 1049–1054), and provided the ideology of clerical independence that led to the Investiture Controversy in the late 11th century. This involved Pope Gregory VII (pope 1073–85) and Emperor Henry IV, who initially clashed over episcopal appointments, a dispute that turned into a battle over the ideas of investiture, clerical marriage, and simony. The emperor saw the protection of the Church as one of his responsibilities as well as wanting to preserve the right to appoint his own choices as bishops within his lands, but the papacy insisted on the Church's independence from secular lords. These issues remained unresolved after the compromise of 1122 known as the Concordat of Worms. The dispute represents a significant stage in the creation of a papal monarchy separate from and equal to lay authorities. It also had the permanent consequence of empowering German princes at the expense of the German emperors.[258]
+
+The High Middle Ages was a period of great religious movements. Besides the Crusades and monastic reforms, people sought to participate in new forms of religious life. New monastic orders were founded, including the Carthusians and the Cistercians. The latter, in particular, expanded rapidly in their early years under the guidance of Bernard of Clairvaux (d. 1153). These new orders were formed in response to the feeling of the laity that Benedictine monasticism no longer met the needs of the laymen, who along with those wishing to enter the religious life wanted a return to the simpler hermetical monasticism of early Christianity, or to live an Apostolic life.[215] Religious pilgrimages were also encouraged. Old pilgrimage sites such as Rome, Jerusalem, and Compostela received increasing numbers of visitors, and new sites such as Monte Gargano and Bari rose to prominence.[260]
+
+In the 13th century mendicant orders—the Franciscans and the Dominicans—who swore vows of poverty and earned their living by begging, were approved by the papacy.[261] Religious groups such as the Waldensians and the Humiliati also attempted to return to the life of early Christianity in the middle 12th and early 13th centuries, another heretical movement condemned by the papacy. Others joined the Cathars, another movement condemned as heretical by the papacy. In 1209, a crusade was preached against the Cathars, the Albigensian Crusade, which in combination with the medieval Inquisition, eliminated them.[262]
+
+The first years of the 14th century were marked by famines, culminating in the Great Famine of 1315–17.[263] The causes of the Great Famine included the slow transition from the Medieval Warm Period to the Little Ice Age, which left the population vulnerable when bad weather caused crop failures.[264] The years 1313–14 and 1317–21 were excessively rainy throughout Europe, resulting in widespread crop failures.[265] The climate change—which resulted in a declining average annual temperature for Europe during the 14th century—was accompanied by an economic downturn.[266]
+
+These troubles were followed in 1347 by the Black Death, a pandemic that spread throughout Europe during the following three years.[267][AD] The death toll was probably about 35 million people in Europe, about one-third of the population. Towns were especially hard-hit because of their crowded conditions.[AE] Large areas of land were left sparsely inhabited, and in some places fields were left unworked. Wages rose as landlords sought to entice the reduced number of available workers to their fields. Further problems were lower rents and lower demand for food, both of which cut into agricultural income. Urban workers also felt that they had a right to greater earnings, and popular uprisings broke out across Europe.[270] Among the uprisings were the jacquerie in France, the Peasants' Revolt in England, and revolts in the cities of Florence in Italy and Ghent and Bruges in Flanders. The trauma of the plague led to an increased piety throughout Europe, manifested by the foundation of new charities, the self-mortification of the flagellants, and the scapegoating of Jews.[271] Conditions were further unsettled by the return of the plague throughout the rest of the 14th century; it continued to strike Europe periodically during the rest of the Middle Ages.[267]
+
+Society throughout Europe was disturbed by the dislocations caused by the Black Death. Lands that had been marginally productive were abandoned, as the survivors were able to acquire more fertile areas.[272] Although serfdom declined in Western Europe it became more common in Eastern Europe, as landlords imposed it on those of their tenants who had previously been free.[273] Most peasants in Western Europe managed to change the work they had previously owed to their landlords into cash rents.[274] The percentage of serfs amongst the peasantry declined from a high of 90 to closer to 50 percent by the end of the period.[170] Landlords also became more conscious of common interests with other landholders, and they joined together to extort privileges from their governments. Partly at the urging of landlords, governments attempted to legislate a return to the economic conditions that existed before the Black Death.[274] Non-clergy became increasingly literate, and urban populations began to imitate the nobility's interest in chivalry.[275]
+
+Jewish communities were expelled from England in 1290 and from France in 1306. Although some were allowed back into France, most were not, and many Jews emigrated eastwards, settling in Poland and Hungary.[276] The Jews were expelled from Spain in 1492, and dispersed to Turkey, France, Italy, and Holland.[79] The rise of banking in Italy during the 13th century continued throughout the 14th century, fuelled partly by the increasing warfare of the period and the needs of the papacy to move money between kingdoms. Many banking firms loaned money to royalty, at great risk, as some were bankrupted when kings defaulted on their loans.[277][AF]
+
+Strong, royalty-based nation states rose throughout Europe in the Late Middle Ages, particularly in England, France, and the Christian kingdoms of the Iberian Peninsula: Aragon, Castile, and Portugal. The long conflicts of the period strengthened royal control over their kingdoms and were extremely hard on the peasantry. Kings profited from warfare that extended royal legislation and increased the lands they directly controlled.[278] Paying for the wars required that methods of taxation become more effective and efficient, and the rate of taxation often increased.[279] The requirement to obtain the consent of taxpayers allowed representative bodies such as the English Parliament and the French Estates General to gain power and authority.[280]
+
+Throughout the 14th century, French kings sought to expand their influence at the expense of the territorial holdings of the nobility.[281] They ran into difficulties when attempting to confiscate the holdings of the English kings in southern France, leading to the Hundred Years' War,[282] waged from 1337 to 1453.[283] Early in the war the English under Edward III (r. 1327–77) and his son Edward, the Black Prince (d. 1376),[AG] won the battles of Crécy and Poitiers, captured the city of Calais, and won control of much of France.[AH] The resulting stresses almost caused the disintegration of the French kingdom during the early years of the war.[286] In the early 15th century, France again came close to dissolving, but in the late 1420s the military successes of Joan of Arc (d. 1431) led to the victory of the French and the capture of the last English possessions in southern France in 1453.[287] The price was high, as the population of France at the end of the Wars was likely half what it had been at the start of the conflict. Conversely, the Wars had a positive effect on English national identity, doing much to fuse the various local identities into a national English ideal. The conflict with France also helped create a national culture in England separate from French culture, which had previously been the dominant influence.[288] The dominance of the English longbow began during early stages of the Hundred Years' War,[289] and cannon appeared on the battlefield at Crécy in 1346.[243]
+
+In modern-day Germany, the Holy Roman Empire continued to rule, but the elective nature of the imperial crown meant there was no enduring dynasty around which a strong state could form.[290] Further east, the kingdoms of Poland, Hungary, and Bohemia grew powerful.[291] In Iberia, the Christian kingdoms continued to gain land from the Muslim kingdoms of the peninsula;[292] Portugal concentrated on expanding overseas during the 15th century, while the other kingdoms were riven by difficulties over royal succession and other concerns.[293][294] After losing the Hundred Years' War, England went on to suffer a long civil war known as the Wars of the Roses, which lasted into the 1490s[294] and only ended when Henry Tudor (r. 1485–1509 as Henry VII) became king and consolidated power with his victory over Richard III (r. 1483–85) at Bosworth in 1485.[295] In Scandinavia, Margaret I of Denmark (r. in Denmark 1387–1412) consolidated Norway, Denmark, and Sweden in the Union of Kalmar, which continued until 1523. The major power around the Baltic Sea was the Hanseatic League, a commercial confederation of city-states that traded from Western Europe to Russia.[296] Scotland emerged from English domination under Robert the Bruce (r. 1306–29), who secured papal recognition of his kingship in 1328.[297]
+
+Although the Palaeologi emperors recaptured Constantinople from the Western Europeans in 1261, they were never able to regain control of much of the former imperial lands. They usually controlled only a small section of the Balkan Peninsula near Constantinople, the city itself, and some coastal lands on the Black Sea and around the Aegean Sea. The former Byzantine lands in the Balkans were divided between the new Kingdom of Serbia, the Second Bulgarian Empire and the city-state of Venice. The power of the Byzantine emperors was threatened by a new Turkish tribe, the Ottomans, who established themselves in Anatolia in the 13th century and steadily expanded throughout the 14th century. The Ottomans expanded into Europe, reducing Bulgaria to a vassal state by 1366 and taking over Serbia after its defeat at the Battle of Kosovo in 1389. Western Europeans rallied to the plight of the Christians in the Balkans and declared a new crusade in 1396; a great army was sent to the Balkans, where it was defeated at the Battle of Nicopolis.[298] Constantinople was finally captured by the Ottomans in 1453.[299]
+
+During the tumultuous 14th century, disputes within the leadership of the Church led to the Avignon Papacy of 1309–76,[300] also called the "Babylonian Captivity of the Papacy" (a reference to the Babylonian captivity of the Jews),[301] and then to the Great Schism, lasting from 1378 to 1418, when there were two and later three rival popes, each supported by several states.[302] Ecclesiastical officials convened at the Council of Constance in 1414, and in the following year the council deposed one of the rival popes, leaving only two claimants. Further depositions followed, and in November 1417, the council elected Martin V (pope 1417–31) as pope.[303]
+
+Besides the schism, the Western Church was riven by theological controversies, some of which turned into heresies. John Wycliffe (d. 1384), an English theologian, was condemned as a heretic in 1415 for teaching that the laity should have access to the text of the Bible as well as for holding views on the Eucharist that were contrary to Church doctrine.[304] Wycliffe's teachings influenced two of the major heretical movements of the later Middle Ages: Lollardy in England and Hussitism in Bohemia.[305] The Bohemian movement initiated with the teaching of Jan Hus, who was burned at the stake in 1415, after being condemned as a heretic by the Council of Constance. The Hussite Church, although the target of a crusade, survived beyond the Middle Ages.[306] Other heresies were manufactured, such as the accusations against the Knights Templar that resulted in their suppression in 1312, and the division of their great wealth between the French King Philip IV (r. 1285–1314) and the Hospitallers.[307]
+
+The papacy further refined the practice in the Mass in the Late Middle Ages, holding that the clergy alone was allowed to partake of the wine in the Eucharist. This further distanced the secular laity from the clergy. The laity continued the practices of pilgrimages, veneration of relics, and belief in the power of the Devil. Mystics such as Meister Eckhart (d. 1327) and Thomas à Kempis (d. 1471) wrote works that taught the laity to focus on their inner spiritual life, which laid the groundwork for the Protestant Reformation. Besides mysticism, belief in witches and witchcraft became widespread, and by the late 15th century the Church had begun to lend credence to populist fears of witchcraft with its condemnation of witches in 1484, and the publication in 1486 of the Malleus Maleficarum, the most popular handbook for witch-hunters.[308]
+
+During the Later Middle Ages, theologians such as John Duns Scotus (d. 1308) and William of Ockham (d. c. 1348)[225] led a reaction against intellectualist scholasticism, objecting to the application of reason to faith. Their efforts undermined the prevailing Platonic idea of universals. Ockham's insistence that reason operates independently of faith allowed science to be separated from theology and philosophy.[309] Legal studies were marked by the steady advance of Roman law into areas of jurisprudence previously governed by customary law. The lone exception to this trend was in England, where the common law remained pre-eminent. Other countries codified their laws; legal codes were promulgated in Castile, Poland, and Lithuania.[310]
+
+Education remained mostly focused on the training of future clergy. The basic learning of the letters and numbers remained the province of the family or a village priest, but the secondary subjects of the trivium—grammar, rhetoric, logic—were studied in cathedral schools or in schools provided by cities. Commercial secondary schools spread, and some Italian towns had more than one such enterprise. Universities also spread throughout Europe in the 14th and 15th centuries. Lay literacy rates rose, but were still low; one estimate gave a literacy rate of 10 per cent of males and 1 per cent of females in 1500.[311]
+
+The publication of vernacular literature increased, with Dante (d. 1321), Petrarch (d. 1374) and Giovanni Boccaccio (d. 1375) in 14th-century Italy, Geoffrey Chaucer (d. 1400) and William Langland (d. c. 1386) in England, and François Villon (d. 1464) and Christine de Pizan (d. c. 1430) in France. Much literature remained religious in character, and although a great deal of it continued to be written in Latin, a new demand developed for saints' lives and other devotional tracts in the vernacular languages.[310] This was fed by the growth of the Devotio Moderna movement, most prominently in the formation of the Brethren of the Common Life, but also in the works of German mystics such as Meister Eckhart and Johannes Tauler (d. 1361).[312] Theatre also developed in the guise of miracle plays put on by the Church.[310] At the end of the period, the development of the printing press in about 1450 led to the establishment of publishing houses throughout Europe by 1500.[313]
+
+In the early 15th century, the countries of the Iberian Peninsula began to sponsor exploration beyond the boundaries of Europe. Prince Henry the Navigator of Portugal (d. 1460) sent expeditions that discovered the Canary Islands, the Azores, and Cape Verde during his lifetime. After his death, exploration continued; Bartolomeu Dias (d. 1500) went around the Cape of Good Hope in 1486, and Vasco da Gama (d. 1524) sailed around Africa to India in 1498.[314] The combined Spanish monarchies of Castile and Aragon sponsored the voyage of exploration by Christopher Columbus (d. 1506) in 1492 that discovered the Americas.[315] The English crown under Henry VII sponsored the voyage of John Cabot (d. 1498) in 1497, which landed on Cape Breton Island.[316]
+
+
+
+One of the major developments in the military sphere during the Late Middle Ages was the increased use of infantry and light cavalry.[317] The English also employed longbowmen, but other countries were unable to create similar forces with the same success.[318] Armour continued to advance, spurred by the increasing power of crossbows, and plate armour was developed to protect soldiers from crossbows as well as the hand-held guns that were developed.[319] Pole arms reached new prominence with the development of the Flemish and Swiss infantry armed with pikes and other long spears.[320]
+
+In agriculture, the increased usage of sheep with long-fibred wool allowed a stronger thread to be spun. In addition, the spinning wheel replaced the traditional distaff for spinning wool, tripling production.[321][AI] A less technological refinement that still greatly affected daily life was the use of buttons as closures for garments, which allowed for better fitting without having to lace clothing on the wearer.[323] Windmills were refined with the creation of the tower mill, allowing the upper part of the windmill to be spun around to face the direction from which the wind was blowing.[324] The blast furnace appeared around 1350 in Sweden, increasing the quantity of iron produced and improving its quality.[325] The first patent law in 1447 in Venice protected the rights of inventors to their inventions.[326]
+
+The Late Middle Ages in Europe as a whole correspond to the Trecento and Early Renaissance cultural periods in Italy. Northern Europe and Spain continued to use Gothic styles, which became increasingly elaborate in the 15th century, until almost the end of the period. International Gothic was a courtly style that reached much of Europe in the decades around 1400, producing masterpieces such as the Très Riches Heures du Duc de Berry.[327] All over Europe secular art continued to increase in quantity and quality, and in the 15th century the mercantile classes of Italy and Flanders became important patrons, commissioning small portraits of themselves in oils as well as a growing range of luxury items such as jewellery, ivory caskets, cassone chests, and maiolica pottery. These objects also included the Hispano-Moresque ware produced by mostly Mudéjar potters in Spain. Although royalty owned huge collections of plate, little survives except for the Royal Gold Cup.[328] Italian silk manufacture developed, so that Western churches and elites no longer needed to rely on imports from Byzantium or the Islamic world. In France and Flanders tapestry weaving of sets like The Lady and the Unicorn became a major luxury industry.[329]
+
+The large external sculptural schemes of Early Gothic churches gave way to more sculpture inside the building, as tombs became more elaborate and other features such as pulpits were sometimes lavishly carved, as in the Pulpit by Giovanni Pisano in Sant'Andrea. Painted or carved wooden relief altarpieces became common, especially as churches created many side-chapels. Early Netherlandish painting by artists such as Jan van Eyck (d. 1441) and Rogier van der Weyden (d. 1464) rivalled that of Italy, as did northern illuminated manuscripts, which in the 15th century began to be collected on a large scale by secular elites, who also commissioned secular books, especially histories. From about 1450 printed books rapidly became popular, though still expensive. There were around 30,000 different editions of incunabula, or works printed before 1500,[330] by which time illuminated manuscripts were commissioned only by royalty and a few others. Very small woodcuts, nearly all religious, were affordable even by peasants in parts of Northern Europe from the middle of the 15th century. More expensive engravings supplied a wealthier market with a variety of images.[331]
+
+The medieval period is frequently caricatured as a "time of ignorance and superstition" that placed "the word of religious authorities over personal experience and rational activity."[332] This is a legacy from both the Renaissance and Enlightenment when scholars favourably contrasted their intellectual cultures with those of the medieval period. Renaissance scholars saw the Middle Ages as a period of decline from the high culture and civilisation of the Classical world. Enlightenment scholars saw reason as superior to faith, and thus viewed the Middle Ages as a time of ignorance and superstition.[16]
+
+Others argue that reason was generally held in high regard during the Middle Ages. Science historian Edward Grant writes, "If revolutionary rational thoughts were expressed [in the 18th century], they were only made possible because of the long medieval tradition that established the use of reason as one of the most important of human activities".[333] Also, contrary to common belief, David Lindberg writes, "the late medieval scholar rarely experienced the coercive power of the Church and would have regarded himself as free (particularly in the natural sciences) to follow reason and observation wherever they led".[334]
+
+The caricature of the period is also reflected in some more specific notions. One misconception, first propagated in the 19th century[335] and still very common, is that all people in the Middle Ages believed that the Earth was flat.[335] This is untrue, as lecturers in the medieval universities commonly argued that evidence showed the Earth was a sphere.[336] Lindberg and Ronald Numbers, another scholar of the period, state that there "was scarcely a Christian scholar of the Middle Ages who did not acknowledge [Earth's] sphericity and even know its approximate circumference".[337] Other misconceptions such as "the Church prohibited autopsies and dissections during the Middle Ages", "the rise of Christianity killed off ancient science", or "the medieval Christian Church suppressed the growth of natural philosophy", are all cited by Numbers as examples of widely popular myths that still pass as historical truth, although they are not supported by historical research.[338]
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+The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Southern Europe and Anatolia, on the south by North Africa, and on the east by the Levant. Although the sea is sometimes considered a part of the Atlantic Ocean, it is usually referred to as a separate body of water. Geological evidence indicates that around 5.9 million years ago, the Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years during the Messinian salinity crisis before being refilled by the Zanclean flood about 5.3 million years ago.
+
+It covers an area of about 2,500,000 km2 (970,000 sq mi),[2] representing 0.7% of the global ocean surface, but its connection to the Atlantic via the Strait of Gibraltar—the narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates Spain in Europe from Morocco in Africa—is only 14 km (9 mi) wide. In oceanography, it is sometimes called the Eurafrican Mediterranean Sea, the European Mediterranean Sea or the African Mediterranean Sea to distinguish it from mediterranean seas elsewhere.[3][4]
+
+The Mediterranean Sea has an average depth of 1,500 m (4,900 ft) and the deepest recorded point is 5,267 m (17,280 ft) in the Calypso Deep in the Ionian Sea. It lies between latitudes 30° and 46° N and longitudes 6° W and 36° E. Its west–east length, from the Strait of Gibraltar to the Gulf of Iskenderun, on the southeastern coast of Turkey, is about 4,000 kilometres (2,500 mi).
+
+The sea was an important route for merchants and travellers of ancient times, facilitating trade and cultural exchange between peoples of the region. The history of the Mediterranean region is crucial to understanding the origins and development of many modern societies. The sea was controlled by the Roman Empire for centuries, during their nautical hegemony.
+
+The countries surrounding the Mediterranean in clockwise order are Spain, France, Monaco, Italy, Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Albania, Greece, Turkey, Syria, Lebanon, Israel, Egypt, Libya, Tunisia, Algeria, and Morocco; Malta and Cyprus are island countries in the sea. In addition, the Gaza Strip and the British Overseas Territories of Gibraltar and Akrotiri and Dhekelia have coastlines on the sea.
+
+The Ancient Egyptians called the Mediterranean Wadj-wr/Wadj-Wer/Wadj-Ur.
+
+The Ancient Greeks called the Mediterranean simply ἡ θάλασσα (hē thálassa; "the Sea") or sometimes ἡ μεγάλη θάλασσα (hē megálē thálassa; "the Great Sea"), ἡ ἡμέτερα θάλασσα (hē hēmétera thálassa; "Our Sea"), or ἡ θάλασσα ἡ καθ'ἡμᾶς (hē thálassa hē kath’hēmâs; "the sea around us").
+
+The Romans called it Mare Magnum ("Great Sea") or Mare Internum ("Internal Sea") and, starting with the Roman Empire, Mare Nostrum ("Our Sea"). The term Mare Mediterrāneum appears later: Solinus apparently used it in the 3rd century, but the earliest extant witness to it is in the 6th century, in Isidore of Seville.[5][6] It means 'in the middle of land, inland' in Latin, a compound of medius ("middle"), terra ("land, earth"), and -āneus ("having the nature of").
+
+The Latin word is a calque of Greek μεσόγειος (mesógeios; "inland"), from μέσος (mésos, "in the middle") and γήινος (gḗinos, "of the earth"), from γῆ (gê, "land, earth"). The original meaning may have been 'the sea in the middle of the earth', rather than 'the sea enclosed by land'.[7][8]
+
+Ancient Iranians called it the "Roman Sea", in Classic Persian texts was called Daryāy-e Rōm (دریای روم) which may be from Middle Persian form, Zrēh ī Hrōm (𐭦𐭫𐭩𐭤 𐭩 𐭤𐭫𐭥𐭬).[9]
+
+The Carthaginians called it the "Syrian Sea". In ancient Syrian texts, Phoenician epics and in the Hebrew Bible, it was primarily known as the "Great Sea", HaYam HaGadol, (Numbers; Book of Joshua; Ezekiel) or simply as "The Sea" (1 Kings).  However, it has also been called the "Hinder Sea" because of its location on the west coast of Greater Syria or the Holy Land (and therefore behind a person facing the east), which is sometimes translated as "Western Sea". Another name was the "Sea of the Philistines", (Book of Exodus), from the people inhabiting a large portion of its shores near the Israelites. In Modern Hebrew, it is called HaYam HaTikhon 'the Middle Sea'.[10] In Classic Persian texts was called Daryāy-e Šām (دریای شام) "The Western Sea" or "Syrian Sea".[11]
+
+In Modern Arabic, it is known as al-Baḥr [al-Abyaḍ] al-Mutawassiṭ (البحر [الأبيض] المتوسط) 'the [White] Middle Sea'. In Islamic and older Arabic literature, it was Baḥr al-Rūm(ī) (بحر الروم or بحر الرومي}) 'the Sea of the Romans' or 'the Roman Sea'. At first, that name referred to only the Eastern Mediterranean, but it was later extended to the whole Mediterranean. Other Arabic names were Baḥr al-šām(ī) (بحر الشام) ("the Sea of Syria") and Baḥr al-Maghrib (بحرالمغرب) ("the Sea of the West").[12][6]
+
+In Turkish, it is the Akdeniz 'the White Sea'; in Ottoman, ﺁق دكيز, which sometimes means only the Aegean Sea.[13] The origin of the name is not clear, as it is not known in earlier Greek, Byzantine or Islamic sources. It may be to contrast with the Black Sea.[12][10][14] In Persian, the name was translated as Baḥr-i Safīd, which was also used in later Ottoman Turkish. It is probably the origin of the colloquial Greek phrase Άσπρη Θάλασσα (Άspri Thálassa, lit. "White Sea").[12]
+
+Johann Knobloch claims that in classical antiquity, cultures in the Levant used colours to refer to the cardinal points: black referred to the north (explaining the name Black Sea), yellow or blue to east, red to south (e.g., the Red Sea), and white to west. This would explain the Greek Άspri Thálassa, the Bulgarian Byalo More, the Turkish Akdeniz, and the Arab nomenclature described above, lit. "White Sea".[15]
+
+Several ancient civilizations were located around the Mediterranean shores and were greatly influenced by their proximity to the sea. It provided routes for trade, colonization, and war, as well as food (from fishing and the gathering of other seafood) for numerous communities throughout the ages.[16]
+
+Due to the shared climate, geology, and access to the sea, cultures centered on the Mediterranean tended to have some extent of intertwined culture and history.
+
+Two of the most notable Mediterranean civilizations in classical antiquity were the Greek city states and the Phoenicians, both of which extensively colonized the coastlines of the Mediterranean. Later, when Augustus founded the Roman Empire, the Romans referred to the Mediterranean as Mare Nostrum ("Our Sea"). For the next 400 years, the Roman Empire completely controlled the Mediterranean Sea and virtually all its coastal regions from Gibraltar to the Levant.
+
+Darius I of Persia, who conquered Ancient Egypt, built a canal linking the Mediterranean to the Red Sea. Darius's canal was wide enough for two triremes to pass each other with oars extended, and required four days to traverse.[17]
+
+In 2019, the archaeological team of experts from Underwater Research Center of the Akdeniz University (UA) revealed a shipwreck dating back 3,600 years in the Mediterranean Sea in Turkey. 1.5 tons of copper ingots found in the ship was used to estimate its age. The Governor of Antalya Munir Karaloğlu described this valuable discovery as the "Göbeklitepe of the underwater world”. It has been confirmed that the shipwreck, dating back to 1600 BC, is older than the "Uluburun Shipwreck" dating back to 1400 BC.[18][19][20][21]
+
+The Western Roman Empire collapsed around 476 AD. Temporarily the east was again dominant as Roman power lived on in the Byzantine Empire formed in the 4th century from the eastern half of the Roman Empire. Another power arose in the 7th century, and with it the religion of Islam, which soon swept across from the east; at its greatest extent, the Arab Empire controlled 75% of the Mediterranean region and left a lasting footprint on its eastern and southern shores.
+
+The Arab invasions disrupted the trade relations between Western and Eastern Europe while disrupting trade routes with Eastern Asian Empires. This, however, had the indirect effect of promoting the trade across the Caspian Sea. The export of grains from Egypt was re-routed towards the Eastern world. Products from East Asian empires, like silk and spices, were carried from Egypt to ports like Venice and Constantinople by sailors and Jewish merchants. The Viking raids further disrupted the trade in western Europe and brought it to a halt. However, the Norsemen developed the trade from Norway to the White Sea, while also trading in luxury goods from Spain and the Mediterranean. The Byzantines in the mid-8th century retook control of the area around the north-eastern part of the Mediterranean. Venetian ships from the 9th century armed themselves to counter the harassment by Arabs while concentrating trade of Asian goods in Venice.[22]
+
+The Fatimids maintained trade relations with the Italian city-states like Amalfi and Genoa before the Crusades, according to the Cairo Geniza documents. A document dated 996 mentions Amalfian merchants living in Cairo. Another letter states that the Genoese had traded with Alexandria. The caliph al-Mustansir had allowed Amalfian merchants to reside in Jerusalem about 1060 in place of the Latin hospice.[23]
+
+The Crusades led to flourishing of trade between Europe and the outremer region.[24] Genoa, Venica and Pisa created colonies in regions controlled by the Crusaders and came to control the trade with the Orient. These colonies also allowed them to trade with the Eastern world. Though the fall of the Crusader states and attempts at banning of trade relations with Muslim states by the Popes temporarily disrupted the trade with the Orient, it however continued.[25]
+
+Europe started to revive, however, as more organized and centralized states began to form in the later Middle Ages after the Renaissance of the 12th century.
+
+Ottoman power based in Anatolia continued to grow, and in 1453 extinguished the Byzantine Empire with the Conquest of Constantinople. Ottomans gained control of much of the sea in the 16th century and maintained naval bases in southern France (1543–1544), Algeria and Tunisia. Barbarossa, the famous Ottoman captain is a symbol of this domination with the victory of the Battle of Preveza (1538). The Battle of Djerba (1560) marked the apex of Ottoman naval domination in the Mediterranean. As the naval prowess of the European powers increased, they confronted Ottoman expansion in the region when the Battle of Lepanto (1571) checked the power of the Ottoman Navy. This was the last naval battle to be fought primarily between galleys.
+
+The Barbary pirates of Northwest Africa preyed on Christian shipping and coastlines in the Western Mediterranean Sea.[26] According to Robert Davis, from the 16th to 19th centuries, pirates captured 1 million to 1.25 million Europeans as slaves.[27]
+
+The development of oceanic shipping began to affect the entire Mediterranean. Once, most trade between Western Europe and the East had passed through the region, but after the 1490s the development of a sea route to the Indian Ocean allowed the importation of Asian spices and other goods through the Atlantic ports of western Europe.[28][29][30]
+
+The sea remained strategically important. British mastery of Gibraltar ensured their influence in Africa and Southwest Asia. Wars included Naval warfare in the Mediterranean during World War I and Mediterranean theatre of World War II.
+
+In 2013, the Maltese president described the Mediterranean Sea as a "cemetery" due to the large number of migrants who drowned there after their boats capsized.[31] European Parliament president Martin Schulz said in 2014 that Europe's migration policy "turned the Mediterranean into a graveyard", referring to the number of drowned refugees in the region as a direct result of the policies.[32] An Azerbaijani official described the sea as "a burial ground ... where people die".[33]
+
+Following the 2013 Lampedusa migrant shipwreck, the Italian government decided to strengthen the national system for the patrolling of the Mediterranean Sea by authorising "Operation Mare Nostrum", a military and humanitarian mission in order to rescue the migrants and arrest the traffickers of immigrants. In 2015, more than one million migrants crossed the Mediterranean Sea into Europe.[34]
+
+Italy was particularly affected by the European migrant crisis. Since 2013, over 700,000 migrants have landed in Italy,[35] mainly sub-Saharan Africans.[36]
+
+The Mediterranean Sea connects:
+
+The 163 km (101 mi) long artificial Suez Canal in the southeast connects the Mediterranean Sea to the Red Sea.[10]
+
+Large islands in the Mediterranean include:
+
+The typical Mediterranean climate has hot, humid, and dry summers and mild, rainy winters. Crops of the region include olives, grapes, oranges, tangerines, and cork.
+
+The Mediterranean Sea includes 14 marginal sea:[37][circular reference][38][circular reference][39][circular reference][40][circular reference][41][circular reference]
+
+The International Hydrographic Organization defines the limits of the Mediterranean Sea as follows:[42] Stretching from the Strait of Gibraltar in the west to the entrances to the Dardanelles and the Suez Canal in the east, the Mediterranean Sea is bounded by the coasts of Europe, Africa, and Asia and is divided into two deep basins:
+
+The following countries have a coastline on the Mediterranean Sea:
+
+Several other territories also border the Mediterranean Sea (from west to east):
+
+Major cities (municipalities), with populations larger than 200,000 people, bordering the Mediterranean Sea include:
+
+The International Hydrographic Organization (IHO) divides the Mediterranean into a number of smaller waterbodies, each with their own designation (from west to east):[42]
+
+Some other seas whose names have been in common use from the ancient times, or in the present:
+
+Many of these smaller seas feature in local myth and folklore and derive their names from such associations.
+
+In addition to the seas, a number of gulfs and straits are recognised:
+
+Much of the Mediterranean coast enjoys a hot-summer Mediterranean climate. However, most of its southeastern coast has a hot desert climate, and much of Spain's eastern (Mediterranean) coast has a cold semi-arid climate. Although they are rare, tropical cyclones occasionally form in the Mediterranean Sea, typically in September–November.
+
+Being nearly landlocked affects conditions in the Mediterranean Sea: for instance, tides are very limited as a result of the narrow connection with the Atlantic Ocean. The Mediterranean is characterised and immediately recognised by its deep blue colour.
+
+Evaporation greatly exceeds precipitation and river runoff in the Mediterranean, a fact that is central to the water circulation within the basin.[58] Evaporation is especially high in its eastern half, causing the water level to decrease and salinity to increase eastward.[59] The average salinity in the basin is 38 PSU at 5 m depth.[60] 
+The temperature of the water in the deepest part of the Mediterranean Sea is 13.2 °C (55.8 °F).[60]
+
+Water circulation in the Mediterranean can be described from the surface waters entering from the Atlantic through the Strait of Gibraltar. These cool and relatively low-salinity waters circulate eastwards along the North African coasts. A part of these surface waters does not pass the Strait of Sicily, but deviates towards Corsica before exiting the Mediterranean. The surface waters entering the eastern Mediterranean basin circulate along the Libyan and Israelian coasts. Upon reaching the Levantine Sea, the surface waters having experienced warming and saltening from their initial Atlantic state, are now more dense and sink to form the Levantine Intermediate Waters (LIW). Most of the water found anywhere between 50 and 600 m deep in the Mediterranean originates from the LIW.[61] LIW are formed along the coasts of Turkey and circulate westwards along the Greek and South Italian coasts. LIW are the only waters passing the Sicily Strait westwards. After the Strait of Sicily, the LIW waters circulate along the Italian, French and Spanish coasts before exiting the Mediterranean through the depths of the Strait of Gibraltar. Deep water in the Mediterranean originates from three main areas: the Adriatic Sea, from which most of the deep water in the eastern Mediterranean originates, the Aegean Sea, and the Gulf of Lion. Deep water formation in the Mediterranean is triggered by strong winter convection fueled by intense cold winds like the Bora. When new deep water is formed, the older waters mix with the overlaying intermediate waters and eventually exit the Mediterranean. The residence time of water in the Mediterranean is approximately 100 years, making the Mediterranean especially sensitive to climate change.[62]
+
+Being a semi-enclosed basin, the Mediterranean experiences transitory events that can affect the water circulation on short time scales. In the mid 1990s, the Aegean Sea became the main area for deep water formation in the eastern Mediterranean after particularly cold winter conditions. This transitory switch in the origin of deep waters in the eastern Mediterranean was termed Eastern Mediterranean Transient (EMT) and had major consequences on water circulation of the Mediterranean.[63][64][65]
+
+Another example of a transient event affecting the Mediterranean circulation is the periodic inversion of the North Ionian Gyre, which is an anticyclonic ocean gyre observed in the northern part of the Ionian Sea, off the Greek coast. The transition from anticyclonic to cyclonic rotation of this gyre changes the origin of the waters fueling it; when the circulation is anticyclonic (most common), the waters of the gyre originate from the Adriatic Sea. When the circulation is cyclonic, the waters originate from the Levantine Sea. These waters have different physical and chemical characteristics, and the periodic inversion of the North Ionian Gyre (called Bimodal Oscillating System or BiOS) changes the Mediterranean circulation and biogeochemistry around the Adriatic and Levantine regions.[66]
+
+Because of the short residence time of waters, the Mediterranean Sea is considered a hot-spot for climate change effects.[67] Deep water temperatures have increased by 0.12 °C (0.22 °F) between 1959 and 1989.[68] According to climate projections, the Mediterranean Sea could become warmer. The decrease in precipitation over the region could lead to more evaporation ultimately increasing the Mediterranean Sea salinity.[67][69] Because of the changes in temperature and salinity, the Mediterranean Sea may become more stratified by the end of the 21st century, with notable consequences on water circulation and biogeochemistry.
+
+In spite of its great biodiversity, concentrations of chlorophyll and nutrients in the Mediterranean Sea are very low, making it one of the most oligotrophic ocean regions in the world. The Mediterranean Sea is commonly referred to as an LNLC (Low-Nutrient, Low-Chlorophyll) area. The Mediterranean Sea fits the definition of a desert as it has low precipitation and its nutrient contents are low, making it difficult for plants and animals to develop.
+
+There are steep gradients in nutrient concentrations, chlorophyll concentrations and primary productivity in the Mediterranean. Nutrient concentrations in the western part of the basin are about double the concentrations in the eastern basin. The Alboran Sea, close to the Strait of Gibraltar, has a daily primary productivity of about 0.25 g C (grams of carbon) m−2 day−1 whereas the eastern basin has an average daily productivity of 0.16 g C m−2 day−1.[70] For this reason, the eastern part of the Mediterranean Sea is termed "ultraoligotrophic". The productive areas of the Mediterranean Sea are few and small. High (i.e. more than 0.5 grams of Chlorophyll a per cubic meter) productivity occurs in coastal areas, close to the river mouths which are the primary suppliers of dissolved nutrients. The Gulf of Lion has a relatively high productivity because it is an area of high vertical mixing, bringing nutrients to the surface waters that can be used by phytoplankton to produce Chlorophyll a.[71]
+
+Primary productivity in the Mediterranean is also marked by an intense seasonal variability. In winter, the strong winds and precipitation[Contradicts statement above that precipitation is low] over the basin generate vertical mixing, bringing nutrients from the deep waters to the surface, where phytoplankton can convert it into biomass.[72] However, in winter, light may be the limiting factor for primary productivity. Between March and April, spring offers the ideal trade-off between light intensity and nutrient concentrations in surface for a spring bloom to occur. In summer, high atmospheric temperatures lead to the warming of the surface waters. The resulting density difference virtually isolates the surface waters from the rest of the water column and nutrient exchanges are limited. As a consequence, primary productivity is very low between June and October.[73][71]
+
+Oceanographic expeditions uncovered a characteristic feature of the Mediterranean Sea biogeochemistry: most of the chlorophyll production does not occur on the surface, but in sub-surface waters between 80 and 200 meters deep.[74] Another key characteristic of the Mediterranean is its high nitrogen-to-phosphorus ratio (N:P). Redfield demonstrated that most of the world's oceans have an average N:P ratio around 16. However, the Mediterranean Sea has an average N:P between 24 and 29, which translates a widespread phosphorus limitation.[clarification needed][75][76][77][78]
+
+Because of its low productivity, plankton assemblages in the Mediterranean Sea are dominated by small organisms such as picophytoplankton and bacteria.[79][80]
+
+The geologic history of the Mediterranean Sea is complex. Underlain by oceanic crust, the sea basin was once thought to be a tectonic remnant of the ancient Tethys Ocean; it is now known to be a structurally younger basin, called the Neotethys, which was first formed by the convergence of the African and Eurasian plates during the Late Triassic and Early Jurassic. Because it is a near-landlocked body of water in a normally dry climate, the Mediterranean is subject to intensive evaporation and the precipitation of evaporites. The Messinian salinity crisis started about six million years ago (mya) when the Mediterranean became landlocked, and then essentially dried up. There are salt deposits accumulated on the bottom of the basin of more than a million cubic kilometres—in some places more than three kilometres thick.[81][82]
+
+Scientists estimate that the sea was last filled about 5.3 million years ago (mya) in less than two years by the Zanclean flood. Water poured in from the Atlantic Ocean through a newly breached gateway now called the Strait of Gibraltar at an estimated rate of about three orders of magnitude (one thousand times) larger than the current flow of the Amazon River.[83]
+
+The Mediterranean Sea has an average depth of 1,500 m (4,900 ft) and the deepest recorded point is 5,267 m (17,280 ft) in the Calypso Deep in the Ionian Sea. The coastline extends for 46,000 km (29,000 mi). A shallow submarine ridge (the Strait of Sicily) between the island of Sicily and the coast of Tunisia divides the sea in two main subregions: the Western Mediterranean, with an area of about 850,000 km2 (330,000 mi2); and the Eastern Mediterranean, of about 1.65 million km2 (640,000 mi2). Coastal areas have submarine karst springs or vruljas, which discharge pressurised groundwater into the water from below the surface; the discharge water is usually fresh, and sometimes may be thermal.[84][85]
+
+The Mediterranean basin and sea system was established by the ancient African-Arabian continent colliding with the Eurasian continent. As Africa-Arabia drifted northward, it closed over the ancient Tethys Ocean which had earlier separated the two supercontinents Laurasia and Gondwana.
+At about that time in the middle Jurassic period (roughly 170 million years ago[dubious  – discuss]) a much smaller sea basin, dubbed the Neotethys, was formed shortly before the Tethys Ocean closed at its western (Arabian) end. The broad line of collisions pushed up a very long system of mountains from the Pyrenees in Spain to the Zagros Mountains in Iran in an episode of mountain-building tectonics known as the Alpine orogeny. The Neotethys grew larger during the episodes of collisions (and associated foldings and subductions) that occurred during the Oligocene and Miocene epochs (34 to 5.33 mya); see animation: Africa-Arabia colliding with Eurasia. Accordingly, the Mediterranean basin consists of several stretched tectonic plates in subduction which are the foundation of the eastern part of the Mediterranean Sea. Various zones of subduction contain the highest oceanic ridges, east of the Ionian Sea and south of the Aegean. The Central Indian Ridge runs east of the Mediterranean Sea south-east across the in-between[clarification needed] of Africa and the Arabian Peninsula into the Indian Ocean.
+
+During Mesozoic and Cenozoic times, as the northwest corner of Africa converged on Iberia, it lifted the Betic-Rif mountain belts across southern Iberia and northwest Africa. There the development of the intramontane Betic and Rif basins created two roughly-parallel marine gateways between the Atlantic Ocean and the Mediterranean Sea. Dubbed the Betic and Rifian corridors, they gradually closed during the middle and late Miocene: perhaps several times.[86] In the late Miocene the closure of the Betic Corridor triggered the so-called "Messinian salinity crisis" (MSC), when the Mediterranean almost entirely dried out. The start of the MSC was recently estimated astronomically at 5.96 mya, and it persisted for some 630,000 years until about 5.3 mya;[87] see Animation: Messinian salinity crisis, at right.
+
+After the initial drawdown[clarification needed] and re-flooding, there followed more episodes—the total number is debated—of sea drawdowns and re-floodings for the duration of the MSC. It ended when the Atlantic Ocean last re-flooded the basin—creating the Strait of Gibraltar and causing the Zanclean flood—at the end of the Miocene (5.33 mya). Some research has suggested that a desiccation-flooding-desiccation cycle may have repeated several times, which could explain several events of large amounts of salt deposition.[88][89] Recent studies, however, show that repeated desiccation and re-flooding is unlikely from a geodynamic point of view.[90][91]
+
+The present-day Atlantic gateway, the Strait of Gibraltar, originated in the early Pliocene via the Zanclean Flood. As mentioned, there were two earlier gateways: the Betic Corridor across southern Spain and the Rifian Corridor across northern Morocco. The Betic closed about 6 mya, causing the Messinian salinity crisis (MSC); the Rifian or possibly both gateways closed during the earlier Tortonian times, causing a "Tortonian salinity crisis" (from 11.6 to 7.2 mya), long before the MSC and lasting much longer. Both "crises" resulted in broad connections between the mainlands of Africa and Europe, which allowed migrations of flora and fauna—especially large mammals including primates—between the two continents. The Vallesian crisis indicates a typical extinction and replacement of mammal species in Europe during Tortonian times following climatic upheaval and overland migrations of new species:[92] see Animation: Messinian salinity crisis (and mammal migrations), at right.
+
+The almost complete enclosure of the Mediterranean basin has enabled the oceanic gateways to dominate seawater circulation and the environmental evolution of the sea and basin. Circulation patterns are also affected by several other factors—including climate, bathymetry, and water chemistry and temperature—which are interactive and can induce precipitation of evaporites. Deposits of evaporites accumulated earlier in the nearby Carpathian foredeep during the Middle Miocene, and the adjacent Red Sea Basin (during the Late Miocene), and in the whole Mediterranean basin (during the MSC and the Messinian age). Many diatomites are found underneath the evaporite deposits, suggesting a connection between their[clarification needed] formations.
+
+Today, evaporation of surface seawater (output) is more than the supply (input) of fresh water by precipitation and coastal drainage systems, causing the salinity of the Mediterranean to be much higher than that of the Atlantic—so much so that the saltier Mediterranean waters sink below the waters incoming from the Atlantic, causing a two-layer flow across the Strait of Gibraltar: that is, an outflow submarine current of warm saline Mediterranean water, counterbalanced by an inflow surface current of less saline cold oceanic water from the Atlantic. In the 1920s, Herman Sörgel proposed the building of a hydroelectric dam (the Atlantropa project) across the Straits, using the inflow current to provide a large amount of hydroelectric energy. The underlying energy grid was also intended to support a political union between Europe and, at least, the Maghreb part of Africa (compare Eurafrika for the later impact and Desertec for a later project with some parallels in the planned grid).[93]
+
+The end of the Miocene also marked a change in the climate of the Mediterranean basin. Fossil evidence from that period reveals that the larger basin had a humid subtropical climate with rainfall in the summer supporting laurel forests. The shift to a "Mediterranean climate" occurred largely within the last three million years (the late Pliocene epoch) as summer rainfall decreased. The subtropical laurel forests retreated; and even as they persisted on the islands of Macaronesia off the Atlantic coast of Iberia and North Africa, the present Mediterranean vegetation evolved, dominated by coniferous trees and sclerophyllous trees and shrubs with small, hard, waxy leaves that prevent moisture loss in the dry summers. Much of these forests and shrublands have been altered beyond recognition by thousands of years of human habitation. There are now very few relatively intact natural areas in what was once a heavily wooded region.
+
+Because of its latitude and its land-locked position, the Mediterranean is especially sensitive to astronomically induced climatic variations, which are well documented in its sedimentary record. Since the Mediterranean is subject to the deposition of eolian dust from the Sahara during dry periods, whereas riverine detrital input prevails during wet ones, the Mediterranean marine sapropel-bearing sequences provide high-resolution climatic information. These data have been employed in reconstructing astronomically calibrated time scales for the last 9 Ma of the Earth's history, helping to constrain the time of past geomagnetic reversals.[94] Furthermore, the exceptional accuracy of these paleoclimatic records has improved our knowledge of the Earth's orbital variations in the past.
+
+Unlike the vast multidirectional ocean currents in open oceans within their respective oceanic zones; biodiversity in the Mediterranean Sea is that of a stable one due to the subtle but strong locked nature of currents which affects favorably, even the smallest macroscopic type of volcanic life form. The stable marine ecosystem of the Mediterranean Sea and sea temperature provides a nourishing environment for life in the deep sea to flourish while assuring a balanced aquatic ecosystem excluded from any external deep oceanic factors. It is estimated that there are more than 17,000 marine species in the Mediterranean Sea with generally higher marine biodiversity in coastal areas, continental shelves, and decreases with depth.[95]
+
+As a result of the drying of the sea during the Messinian salinity crisis,[96] the marine biota of the Mediterranean are derived primarily from the Atlantic Ocean. The North Atlantic is considerably colder and more nutrient-rich than the Mediterranean, and the marine life of the Mediterranean has had to adapt to its differing conditions in the five million years since the basin was reflooded.
+
+The Alboran Sea is a transition zone between the two seas, containing a mix of Mediterranean and Atlantic species. The Alboran Sea has the largest population of bottlenose dolphins in the Western Mediterranean, is home to the last population of harbour porpoises in the Mediterranean, and is the most important feeding grounds for loggerhead sea turtles in Europe. The Alboran Sea also hosts important commercial fisheries, including sardines and swordfish. The Mediterranean monk seals live in the Aegean Sea in Greece. In 2003, the World Wildlife Fund raised concerns about the widespread drift net fishing endangering populations of dolphins, turtles, and other marine animals such as the spiny squat lobster.
+
+There was a resident population of killer whale in the Mediterranean until the 1980s, when they went extinct, probably due to long term PCB exposure. There are still annual sightings of killer whale vagrants.[97]
+
+For 4,000 years, human activity has transformed most parts of Mediterranean Europe, and the "humanisation of the landscape" overlapped with the appearance of the present Mediterranean climate.[98] The image of a simplistic, environmental determinist notion of a Mediterranean paradise on Earth in antiquity, which was destroyed by later civilisations, dates back to at least the 18th century and was for centuries fashionable in archaeological and historical circles. Based on a broad variety of methods, e.g. historical documents, analysis of trade relations, floodplain sediments, pollen, tree-ring and further archaeometric analyses and population studies, Alfred Thomas Grove's and Oliver Rackham's work on "The Nature of Mediterranean Europe" challenges this common wisdom of a Mediterranean Europe as a "Lost Eden", a formerly fertile and forested region, that had been progressively degraded and desertified by human mismanagement.[98] The belief stems more from the failure of the recent landscape to measure up to the imaginary past of the classics as idealised by artists, poets and scientists of the early modern Enlightenment.[98]
+
+The historical evolution of climate, vegetation and landscape in southern Europe from prehistoric times to the present is much more complex and underwent various changes. For example, some of the deforestation had already taken place before the Roman age. While in the Roman age large enterprises such as the latifundia took effective care of forests and agriculture, the largest depopulation effects came with the end of the empire. Some[who?] assume that the major deforestation took place in modern times—the later usage patterns were also quite different e.g. in southern and northern Italy. Also, the climate has usually been unstable and there is evidence of various ancient and modern "Little Ice Ages",[99] and plant cover accommodated to various extremes and became resilient to various patterns of human activity.[98]
+
+Human activity was therefore not the cause of climate change but followed it.[98] The wide ecological diversity typical of Mediterranean Europe is predominantly based on human behavior, as it is and has been closely related human usage patterns.[98] The diversity range[clarification needed] was enhanced by the widespread exchange and interaction of the longstanding and highly diverse local agriculture, intense transport and trade relations, and the interaction with settlements, pasture and other land use. The greatest human-induced changes, however, came after World War II, in line with the "1950s syndrome"[100] as rural populations throughout the region abandoned traditional subsistence economies. Grove and Rackham suggest that the locals left the traditional agricultural patterns and instead became scenery-setting agents[clarification needed] for tourism. This resulted in more uniform, large-scale formations[of what?].[98] Among further current important threats to Mediterranean landscapes are overdevelopment of coastal areas, abandonment of mountains and, as mentioned, the loss of variety via the reduction of traditional agricultural occupations.[98]
+
+The region has a variety of geological hazards which have closely interacted with human activity and land use patterns. Among others, in the eastern Mediterranean, the Thera eruption, dated to the 17th or 16th century BC, caused a large tsunami that some experts hypothesise devastated the Minoan civilisation on the nearby island of Crete, further leading some to believe that this may have been the catastrophe that inspired the Atlantis legend.[101] Mount Vesuvius is the only active volcano on the European mainland, while others, Mount Etna and Stromboli, are on neighbouring islands. The region around Vesuvius including the Phlegraean Fields Caldera west of Naples are quite active[102] and constitute the most densely populated volcanic region in the world where an eruptive event may occur within decades.[103]
+
+Vesuvius itself is regarded as quite dangerous due to a tendency towards explosive (Plinian) eruptions.[104] It is best known for its eruption in AD 79 that led to the burying and destruction of the Roman cities of Pompeii and Herculaneum.
+
+The large experience[clarification needed] of member states and regional authorities has led to exchange[of what?] on the international level with cooperation of NGOs, states, regional and municipality authorities and private persons.[105] The Greek–Turkish earthquake diplomacy is a quite positive example of natural hazards leading to improved relations between traditional rivals in the region after earthquakes in İzmir and Athens in 1999. The European Union Solidarity Fund (EUSF) was set up to respond to major natural disasters and express European solidarity to disaster-stricken regions within all of Europe.[106] The largest amount of funding requests in the EU relates to forest fires, followed by floods and earthquakes. Forest fires, whether man made or natural, are a frequent and dangerous hazard in the Mediterranean region.[105] Tsunamis are also an often underestimated hazard in the region. For example, the 1908 Messina earthquake and tsunami took more than 123,000 lives in Sicily and Calabria and was among the most deadly natural disasters in modern Europe.
+
+The opening of the Suez Canal in 1869 created the first salt-water passage between the Mediterranean and the Red Sea. The Red Sea is higher than the Eastern Mediterranean, so the canal functions as a tidal strait that pours Red Sea water into the Mediterranean. The Bitter Lakes, which are hyper-saline natural lakes that form part of the canal, blocked the migration of Red Sea species into the Mediterranean for many decades, but as the salinity of the lakes gradually equalised with that of the Red Sea, the barrier to migration was removed, and plants and animals from the Red Sea have begun to colonise the Eastern Mediterranean. The Red Sea is generally saltier and more nutrient-poor than the Atlantic, so the Red Sea species have advantages over Atlantic species in the salty and nutrient-poor Eastern Mediterranean. Accordingly, Red Sea species invade the Mediterranean biota, and not vice versa; this phenomenon is known as the Lessepsian migration (after Ferdinand de Lesseps, the French engineer) or Erythrean ("red") invasion. The construction of the Aswan High Dam across the Nile River in the 1960s reduced the inflow of freshwater and nutrient-rich silt from the Nile into the Eastern Mediterranean, making conditions there even more like the Red Sea and worsening the impact of the invasive species.
+
+Invasive species have become a major component of the Mediterranean ecosystem and have serious impacts on the Mediterranean ecology, endangering many local and endemic Mediterranean species. A first look at some groups of exotic species shows that more than 70% of the non-indigenous decapods and about 63% of the exotic fishes occurring in the Mediterranean are of Indo-Pacific origin,[107] introduced into the Mediterranean through the Suez Canal. This makes the Canal the first pathway of arrival of alien species into the Mediterranean. The impacts of some Lessepsian species have proven to be considerable, mainly in the Levantine basin of the Mediterranean, where they are replacing native species and becoming a familiar sight.
+
+According to the International Union for Conservation of Nature definition, as well as Convention on Biological Diversity (CBD) and Ramsar Convention terminologies, they are alien species, as they are non-native (non-indigenous) to the Mediterranean Sea, and they are outside their normal area of distribution which is the Indo-Pacific region. When these species succeed in establishing populations in the Mediterranean Sea, compete with and begin to replace native species they are "Alien Invasive Species", as they are an agent of change and a threat to the native biodiversity. In the context of CBD, "introduction" refers to the movement by human agency, indirect or direct, of an alien species outside of its natural range (past or present). The Suez Canal, being an artificial (man made) canal, is a human agency. Lessepsian migrants are therefore "introduced" species (indirect, and unintentional). Whatever wording is chosen, they represent a threat to the native Mediterranean biodiversity, because they are non-indigenous to this sea. In recent years, the Egyptian government's announcement of its intentions to deepen and widen the canal have raised concerns from marine biologists, fearing that such an act will only worsen the invasion of Red Sea species into the Mediterranean, and lead to even more species passing through the canal.[108]
+
+In recent decades, the arrival of exotic species from the tropical Atlantic has become noticeable. Whether this reflects an expansion of the natural area of these species that now enter the Mediterranean through the Gibraltar strait, because of a warming trend of the water caused by global warming; or an extension of the maritime traffic; or is simply the result of a more intense scientific investigation, is still an open question. While not as intense as the "Lessepsian" movement, the process may be of scientific interest and may therefore[non sequitur] warrant increased levels of monitoring.[citation needed]
+
+By 2100 the overall level of the Mediterranean could rise between 3 to 61 cm (1.2 to 24.0 in) as a result of the effects of climate change.[109] This could have adverse effects on populations across the Mediterranean:
+
+Coastal ecosystems also appear to be threatened by sea level rise, especially enclosed seas such as the Baltic, the Mediterranean and the Black Sea. These seas have only small and primarily east–west movement corridors, which may restrict northward displacement of organisms in these areas.[113] Sea level rise for the next century (2100) could be between 30 cm (12 in) and 100 cm (39 in) and temperature shifts of a mere 0.05–0.1 °C in the deep sea are sufficient to induce significant changes in species richness and functional diversity.[114]
+
+Pollution in this region has been extremely high in recent years.[when?] The United Nations Environment Programme has estimated that 650,000,000 t (720,000,000 short tons) of sewage, 129,000 t (142,000 short tons) of mineral oil, 60,000 t (66,000 short tons) of mercury, 3,800 t (4,200 short tons) of lead and 36,000 t (40,000 short tons) of phosphates are dumped into the Mediterranean each year.[115] The Barcelona Convention aims to 'reduce pollution in the Mediterranean Sea and protect and improve the marine environment in the area, thereby contributing to its sustainable development.'[116]
+Many marine species have been almost wiped out because of the sea's pollution. One of them is the Mediterranean monk seal which is considered to be among the world's most endangered marine mammals.[117]
+
+The Mediterranean is also plagued by marine debris. A 1994 study of the seabed using trawl nets around the coasts of Spain, France and Italy reported a particularly high mean concentration of debris; an average of 1,935 items per km2. Plastic debris accounted for 76%, of which 94% was plastic bags.[118]
+
+Some of the world's busiest shipping routes are in the Mediterranean Sea. It is estimated that approximately 220,000 merchant vessels of more than 100 tonnes cross the Mediterranean Sea each year—about one third of the world's total merchant shipping. These ships often carry hazardous cargo, which if lost would result in severe damage to the marine environment.
+
+The discharge of chemical tank washings and oily wastes also represent a significant source of marine pollution. The Mediterranean Sea constitutes 0.7% of the global water surface and yet receives 17% of global marine oil pollution. It is estimated that every year between 100,000 t (98,000 long tons) and 150,000 t (150,000 long tons) of crude oil are deliberately released into the sea from shipping activities.
+
+Approximately 370,000,000 t (360,000,000 long tons) of oil are transported annually in the Mediterranean Sea (more than 20% of the world total), with around 250–300 oil tankers crossing the sea every day. Accidental oil spills happen frequently with an average of 10 spills per year. A major oil spill could occur at any time in any part of the Mediterranean.[114]
+
+Tourism is one of the most important sources of income for many Mediterranean countries, despite the man-made geopolitical conflicts[clarification needed] in the region. The countries have tried to extinguish rising man-made chaotic zones[clarification needed] that might affect the region's economies and societies in neighboring coastal countries, and shipping routes. Naval and rescue components in the Mediterranean Sea are considered to be among the best[citation needed] due to the rapid cooperation between various naval fleets. Unlike the vast open oceans, the sea's closed position facilitates effective naval and rescue missions[citation needed], considered the safest[citation needed] and regardless of[clarification needed] any man-made or natural disaster.
+
+Tourism is a source of income for small coastal communities, including islands, independent of urban centers. However, tourism has also played major role in the degradation of the coastal and marine environment. Rapid development has been encouraged by Mediterranean governments to support the large numbers of tourists visiting the region; but this has caused serious disturbance to marine habitats by erosion and pollution in many places along the Mediterranean coasts.
+
+Tourism often concentrates in areas of high natural wealth[clarification needed], causing a serious threat to the habitats of endangered species such as sea turtles and monk seals. Reductions in natural wealth may reduce the incentive for tourists to visit.[114]
+
+Fish stock levels in the Mediterranean Sea are alarmingly low. The European Environment Agency says that more than 65% of all fish stocks in the region are outside safe biological limits and the United Nations Food and Agriculture Organisation, that some of the most important fisheries—such as albacore and bluefin tuna, hake, marlin, swordfish, red mullet and sea bream—are threatened.[date missing]
+
+There are clear indications that catch size and quality have declined, often dramatically, and in many areas larger and longer-lived species have disappeared entirely from commercial catches.
+
+Large open water fish like tuna have been a shared fisheries resource for thousands of years but the stocks are now dangerously low. In 1999, Greenpeace published a report revealing that the amount of bluefin tuna in the Mediterranean had decreased by over 80% in the previous 20 years and government scientists warn that without immediate action the stock will collapse.
+
+Beach of Hammamet, Tunisia
+
+The beach of la Courtade in the Îles d'Hyères, France
+
+Sardinia's south coast, Italy
+
+Pretty Bay, Malta
+
+Panoramic view of Piran, Slovenia
+
+Panoramic view of Cavtat, Croatia
+
+View of Neum, Bosnia and Herzegovina
+
+A view of Sveti Stefan, Montenegro
+
+Ksamil Islands, Albania
+
+Navagio, Greece
+
+Marmaris, Turquoise Coast, Turkey
+
+Paphos, Cyprus
+
+Burj Islam Beach, Latakia, Syria
+
+A view of Raouché off the coast of Beirut, Lebanon
+
+A view of Haifa, Israel
+
+Coast of Alexandria, view From Bibliotheca Alexandrina, Egypt
+
+Old city of Ibiza Town, Spain
+
+Les Aiguades near Béjaïa, Algeria
+
+El Jebha, a port town in Morocco
+
+Europa Point, Gibraltar
+
+Panoramic view of La Condamine, Monaco
+
+Sunset at the Deir al-Balah beach, Gaza Strip

en/3757.html.txt

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+
+
+The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Southern Europe and Anatolia, on the south by North Africa, and on the east by the Levant. Although the sea is sometimes considered a part of the Atlantic Ocean, it is usually referred to as a separate body of water. Geological evidence indicates that around 5.9 million years ago, the Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years during the Messinian salinity crisis before being refilled by the Zanclean flood about 5.3 million years ago.
+
+It covers an area of about 2,500,000 km2 (970,000 sq mi),[2] representing 0.7% of the global ocean surface, but its connection to the Atlantic via the Strait of Gibraltar—the narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates Spain in Europe from Morocco in Africa—is only 14 km (9 mi) wide. In oceanography, it is sometimes called the Eurafrican Mediterranean Sea, the European Mediterranean Sea or the African Mediterranean Sea to distinguish it from mediterranean seas elsewhere.[3][4]
+
+The Mediterranean Sea has an average depth of 1,500 m (4,900 ft) and the deepest recorded point is 5,267 m (17,280 ft) in the Calypso Deep in the Ionian Sea. It lies between latitudes 30° and 46° N and longitudes 6° W and 36° E. Its west–east length, from the Strait of Gibraltar to the Gulf of Iskenderun, on the southeastern coast of Turkey, is about 4,000 kilometres (2,500 mi).
+
+The sea was an important route for merchants and travellers of ancient times, facilitating trade and cultural exchange between peoples of the region. The history of the Mediterranean region is crucial to understanding the origins and development of many modern societies. The sea was controlled by the Roman Empire for centuries, during their nautical hegemony.
+
+The countries surrounding the Mediterranean in clockwise order are Spain, France, Monaco, Italy, Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Albania, Greece, Turkey, Syria, Lebanon, Israel, Egypt, Libya, Tunisia, Algeria, and Morocco; Malta and Cyprus are island countries in the sea. In addition, the Gaza Strip and the British Overseas Territories of Gibraltar and Akrotiri and Dhekelia have coastlines on the sea.
+
+The Ancient Egyptians called the Mediterranean Wadj-wr/Wadj-Wer/Wadj-Ur.
+
+The Ancient Greeks called the Mediterranean simply ἡ θάλασσα (hē thálassa; "the Sea") or sometimes ἡ μεγάλη θάλασσα (hē megálē thálassa; "the Great Sea"), ἡ ἡμέτερα θάλασσα (hē hēmétera thálassa; "Our Sea"), or ἡ θάλασσα ἡ καθ'ἡμᾶς (hē thálassa hē kath’hēmâs; "the sea around us").
+
+The Romans called it Mare Magnum ("Great Sea") or Mare Internum ("Internal Sea") and, starting with the Roman Empire, Mare Nostrum ("Our Sea"). The term Mare Mediterrāneum appears later: Solinus apparently used it in the 3rd century, but the earliest extant witness to it is in the 6th century, in Isidore of Seville.[5][6] It means 'in the middle of land, inland' in Latin, a compound of medius ("middle"), terra ("land, earth"), and -āneus ("having the nature of").
+
+The Latin word is a calque of Greek μεσόγειος (mesógeios; "inland"), from μέσος (mésos, "in the middle") and γήινος (gḗinos, "of the earth"), from γῆ (gê, "land, earth"). The original meaning may have been 'the sea in the middle of the earth', rather than 'the sea enclosed by land'.[7][8]
+
+Ancient Iranians called it the "Roman Sea", in Classic Persian texts was called Daryāy-e Rōm (دریای روم) which may be from Middle Persian form, Zrēh ī Hrōm (𐭦𐭫𐭩𐭤 𐭩 𐭤𐭫𐭥𐭬).[9]
+
+The Carthaginians called it the "Syrian Sea". In ancient Syrian texts, Phoenician epics and in the Hebrew Bible, it was primarily known as the "Great Sea", HaYam HaGadol, (Numbers; Book of Joshua; Ezekiel) or simply as "The Sea" (1 Kings).  However, it has also been called the "Hinder Sea" because of its location on the west coast of Greater Syria or the Holy Land (and therefore behind a person facing the east), which is sometimes translated as "Western Sea". Another name was the "Sea of the Philistines", (Book of Exodus), from the people inhabiting a large portion of its shores near the Israelites. In Modern Hebrew, it is called HaYam HaTikhon 'the Middle Sea'.[10] In Classic Persian texts was called Daryāy-e Šām (دریای شام) "The Western Sea" or "Syrian Sea".[11]
+
+In Modern Arabic, it is known as al-Baḥr [al-Abyaḍ] al-Mutawassiṭ (البحر [الأبيض] المتوسط) 'the [White] Middle Sea'. In Islamic and older Arabic literature, it was Baḥr al-Rūm(ī) (بحر الروم or بحر الرومي}) 'the Sea of the Romans' or 'the Roman Sea'. At first, that name referred to only the Eastern Mediterranean, but it was later extended to the whole Mediterranean. Other Arabic names were Baḥr al-šām(ī) (بحر الشام) ("the Sea of Syria") and Baḥr al-Maghrib (بحرالمغرب) ("the Sea of the West").[12][6]
+
+In Turkish, it is the Akdeniz 'the White Sea'; in Ottoman, ﺁق دكيز, which sometimes means only the Aegean Sea.[13] The origin of the name is not clear, as it is not known in earlier Greek, Byzantine or Islamic sources. It may be to contrast with the Black Sea.[12][10][14] In Persian, the name was translated as Baḥr-i Safīd, which was also used in later Ottoman Turkish. It is probably the origin of the colloquial Greek phrase Άσπρη Θάλασσα (Άspri Thálassa, lit. "White Sea").[12]
+
+Johann Knobloch claims that in classical antiquity, cultures in the Levant used colours to refer to the cardinal points: black referred to the north (explaining the name Black Sea), yellow or blue to east, red to south (e.g., the Red Sea), and white to west. This would explain the Greek Άspri Thálassa, the Bulgarian Byalo More, the Turkish Akdeniz, and the Arab nomenclature described above, lit. "White Sea".[15]
+
+Several ancient civilizations were located around the Mediterranean shores and were greatly influenced by their proximity to the sea. It provided routes for trade, colonization, and war, as well as food (from fishing and the gathering of other seafood) for numerous communities throughout the ages.[16]
+
+Due to the shared climate, geology, and access to the sea, cultures centered on the Mediterranean tended to have some extent of intertwined culture and history.
+
+Two of the most notable Mediterranean civilizations in classical antiquity were the Greek city states and the Phoenicians, both of which extensively colonized the coastlines of the Mediterranean. Later, when Augustus founded the Roman Empire, the Romans referred to the Mediterranean as Mare Nostrum ("Our Sea"). For the next 400 years, the Roman Empire completely controlled the Mediterranean Sea and virtually all its coastal regions from Gibraltar to the Levant.
+
+Darius I of Persia, who conquered Ancient Egypt, built a canal linking the Mediterranean to the Red Sea. Darius's canal was wide enough for two triremes to pass each other with oars extended, and required four days to traverse.[17]
+
+In 2019, the archaeological team of experts from Underwater Research Center of the Akdeniz University (UA) revealed a shipwreck dating back 3,600 years in the Mediterranean Sea in Turkey. 1.5 tons of copper ingots found in the ship was used to estimate its age. The Governor of Antalya Munir Karaloğlu described this valuable discovery as the "Göbeklitepe of the underwater world”. It has been confirmed that the shipwreck, dating back to 1600 BC, is older than the "Uluburun Shipwreck" dating back to 1400 BC.[18][19][20][21]
+
+The Western Roman Empire collapsed around 476 AD. Temporarily the east was again dominant as Roman power lived on in the Byzantine Empire formed in the 4th century from the eastern half of the Roman Empire. Another power arose in the 7th century, and with it the religion of Islam, which soon swept across from the east; at its greatest extent, the Arab Empire controlled 75% of the Mediterranean region and left a lasting footprint on its eastern and southern shores.
+
+The Arab invasions disrupted the trade relations between Western and Eastern Europe while disrupting trade routes with Eastern Asian Empires. This, however, had the indirect effect of promoting the trade across the Caspian Sea. The export of grains from Egypt was re-routed towards the Eastern world. Products from East Asian empires, like silk and spices, were carried from Egypt to ports like Venice and Constantinople by sailors and Jewish merchants. The Viking raids further disrupted the trade in western Europe and brought it to a halt. However, the Norsemen developed the trade from Norway to the White Sea, while also trading in luxury goods from Spain and the Mediterranean. The Byzantines in the mid-8th century retook control of the area around the north-eastern part of the Mediterranean. Venetian ships from the 9th century armed themselves to counter the harassment by Arabs while concentrating trade of Asian goods in Venice.[22]
+
+The Fatimids maintained trade relations with the Italian city-states like Amalfi and Genoa before the Crusades, according to the Cairo Geniza documents. A document dated 996 mentions Amalfian merchants living in Cairo. Another letter states that the Genoese had traded with Alexandria. The caliph al-Mustansir had allowed Amalfian merchants to reside in Jerusalem about 1060 in place of the Latin hospice.[23]
+
+The Crusades led to flourishing of trade between Europe and the outremer region.[24] Genoa, Venica and Pisa created colonies in regions controlled by the Crusaders and came to control the trade with the Orient. These colonies also allowed them to trade with the Eastern world. Though the fall of the Crusader states and attempts at banning of trade relations with Muslim states by the Popes temporarily disrupted the trade with the Orient, it however continued.[25]
+
+Europe started to revive, however, as more organized and centralized states began to form in the later Middle Ages after the Renaissance of the 12th century.
+
+Ottoman power based in Anatolia continued to grow, and in 1453 extinguished the Byzantine Empire with the Conquest of Constantinople. Ottomans gained control of much of the sea in the 16th century and maintained naval bases in southern France (1543–1544), Algeria and Tunisia. Barbarossa, the famous Ottoman captain is a symbol of this domination with the victory of the Battle of Preveza (1538). The Battle of Djerba (1560) marked the apex of Ottoman naval domination in the Mediterranean. As the naval prowess of the European powers increased, they confronted Ottoman expansion in the region when the Battle of Lepanto (1571) checked the power of the Ottoman Navy. This was the last naval battle to be fought primarily between galleys.
+
+The Barbary pirates of Northwest Africa preyed on Christian shipping and coastlines in the Western Mediterranean Sea.[26] According to Robert Davis, from the 16th to 19th centuries, pirates captured 1 million to 1.25 million Europeans as slaves.[27]
+
+The development of oceanic shipping began to affect the entire Mediterranean. Once, most trade between Western Europe and the East had passed through the region, but after the 1490s the development of a sea route to the Indian Ocean allowed the importation of Asian spices and other goods through the Atlantic ports of western Europe.[28][29][30]
+
+The sea remained strategically important. British mastery of Gibraltar ensured their influence in Africa and Southwest Asia. Wars included Naval warfare in the Mediterranean during World War I and Mediterranean theatre of World War II.
+
+In 2013, the Maltese president described the Mediterranean Sea as a "cemetery" due to the large number of migrants who drowned there after their boats capsized.[31] European Parliament president Martin Schulz said in 2014 that Europe's migration policy "turned the Mediterranean into a graveyard", referring to the number of drowned refugees in the region as a direct result of the policies.[32] An Azerbaijani official described the sea as "a burial ground ... where people die".[33]
+
+Following the 2013 Lampedusa migrant shipwreck, the Italian government decided to strengthen the national system for the patrolling of the Mediterranean Sea by authorising "Operation Mare Nostrum", a military and humanitarian mission in order to rescue the migrants and arrest the traffickers of immigrants. In 2015, more than one million migrants crossed the Mediterranean Sea into Europe.[34]
+
+Italy was particularly affected by the European migrant crisis. Since 2013, over 700,000 migrants have landed in Italy,[35] mainly sub-Saharan Africans.[36]
+
+The Mediterranean Sea connects:
+
+The 163 km (101 mi) long artificial Suez Canal in the southeast connects the Mediterranean Sea to the Red Sea.[10]
+
+Large islands in the Mediterranean include:
+
+The typical Mediterranean climate has hot, humid, and dry summers and mild, rainy winters. Crops of the region include olives, grapes, oranges, tangerines, and cork.
+
+The Mediterranean Sea includes 14 marginal sea:[37][circular reference][38][circular reference][39][circular reference][40][circular reference][41][circular reference]
+
+The International Hydrographic Organization defines the limits of the Mediterranean Sea as follows:[42] Stretching from the Strait of Gibraltar in the west to the entrances to the Dardanelles and the Suez Canal in the east, the Mediterranean Sea is bounded by the coasts of Europe, Africa, and Asia and is divided into two deep basins:
+
+The following countries have a coastline on the Mediterranean Sea:
+
+Several other territories also border the Mediterranean Sea (from west to east):
+
+Major cities (municipalities), with populations larger than 200,000 people, bordering the Mediterranean Sea include:
+
+The International Hydrographic Organization (IHO) divides the Mediterranean into a number of smaller waterbodies, each with their own designation (from west to east):[42]
+
+Some other seas whose names have been in common use from the ancient times, or in the present:
+
+Many of these smaller seas feature in local myth and folklore and derive their names from such associations.
+
+In addition to the seas, a number of gulfs and straits are recognised:
+
+Much of the Mediterranean coast enjoys a hot-summer Mediterranean climate. However, most of its southeastern coast has a hot desert climate, and much of Spain's eastern (Mediterranean) coast has a cold semi-arid climate. Although they are rare, tropical cyclones occasionally form in the Mediterranean Sea, typically in September–November.
+
+Being nearly landlocked affects conditions in the Mediterranean Sea: for instance, tides are very limited as a result of the narrow connection with the Atlantic Ocean. The Mediterranean is characterised and immediately recognised by its deep blue colour.
+
+Evaporation greatly exceeds precipitation and river runoff in the Mediterranean, a fact that is central to the water circulation within the basin.[58] Evaporation is especially high in its eastern half, causing the water level to decrease and salinity to increase eastward.[59] The average salinity in the basin is 38 PSU at 5 m depth.[60] 
+The temperature of the water in the deepest part of the Mediterranean Sea is 13.2 °C (55.8 °F).[60]
+
+Water circulation in the Mediterranean can be described from the surface waters entering from the Atlantic through the Strait of Gibraltar. These cool and relatively low-salinity waters circulate eastwards along the North African coasts. A part of these surface waters does not pass the Strait of Sicily, but deviates towards Corsica before exiting the Mediterranean. The surface waters entering the eastern Mediterranean basin circulate along the Libyan and Israelian coasts. Upon reaching the Levantine Sea, the surface waters having experienced warming and saltening from their initial Atlantic state, are now more dense and sink to form the Levantine Intermediate Waters (LIW). Most of the water found anywhere between 50 and 600 m deep in the Mediterranean originates from the LIW.[61] LIW are formed along the coasts of Turkey and circulate westwards along the Greek and South Italian coasts. LIW are the only waters passing the Sicily Strait westwards. After the Strait of Sicily, the LIW waters circulate along the Italian, French and Spanish coasts before exiting the Mediterranean through the depths of the Strait of Gibraltar. Deep water in the Mediterranean originates from three main areas: the Adriatic Sea, from which most of the deep water in the eastern Mediterranean originates, the Aegean Sea, and the Gulf of Lion. Deep water formation in the Mediterranean is triggered by strong winter convection fueled by intense cold winds like the Bora. When new deep water is formed, the older waters mix with the overlaying intermediate waters and eventually exit the Mediterranean. The residence time of water in the Mediterranean is approximately 100 years, making the Mediterranean especially sensitive to climate change.[62]
+
+Being a semi-enclosed basin, the Mediterranean experiences transitory events that can affect the water circulation on short time scales. In the mid 1990s, the Aegean Sea became the main area for deep water formation in the eastern Mediterranean after particularly cold winter conditions. This transitory switch in the origin of deep waters in the eastern Mediterranean was termed Eastern Mediterranean Transient (EMT) and had major consequences on water circulation of the Mediterranean.[63][64][65]
+
+Another example of a transient event affecting the Mediterranean circulation is the periodic inversion of the North Ionian Gyre, which is an anticyclonic ocean gyre observed in the northern part of the Ionian Sea, off the Greek coast. The transition from anticyclonic to cyclonic rotation of this gyre changes the origin of the waters fueling it; when the circulation is anticyclonic (most common), the waters of the gyre originate from the Adriatic Sea. When the circulation is cyclonic, the waters originate from the Levantine Sea. These waters have different physical and chemical characteristics, and the periodic inversion of the North Ionian Gyre (called Bimodal Oscillating System or BiOS) changes the Mediterranean circulation and biogeochemistry around the Adriatic and Levantine regions.[66]
+
+Because of the short residence time of waters, the Mediterranean Sea is considered a hot-spot for climate change effects.[67] Deep water temperatures have increased by 0.12 °C (0.22 °F) between 1959 and 1989.[68] According to climate projections, the Mediterranean Sea could become warmer. The decrease in precipitation over the region could lead to more evaporation ultimately increasing the Mediterranean Sea salinity.[67][69] Because of the changes in temperature and salinity, the Mediterranean Sea may become more stratified by the end of the 21st century, with notable consequences on water circulation and biogeochemistry.
+
+In spite of its great biodiversity, concentrations of chlorophyll and nutrients in the Mediterranean Sea are very low, making it one of the most oligotrophic ocean regions in the world. The Mediterranean Sea is commonly referred to as an LNLC (Low-Nutrient, Low-Chlorophyll) area. The Mediterranean Sea fits the definition of a desert as it has low precipitation and its nutrient contents are low, making it difficult for plants and animals to develop.
+
+There are steep gradients in nutrient concentrations, chlorophyll concentrations and primary productivity in the Mediterranean. Nutrient concentrations in the western part of the basin are about double the concentrations in the eastern basin. The Alboran Sea, close to the Strait of Gibraltar, has a daily primary productivity of about 0.25 g C (grams of carbon) m−2 day−1 whereas the eastern basin has an average daily productivity of 0.16 g C m−2 day−1.[70] For this reason, the eastern part of the Mediterranean Sea is termed "ultraoligotrophic". The productive areas of the Mediterranean Sea are few and small. High (i.e. more than 0.5 grams of Chlorophyll a per cubic meter) productivity occurs in coastal areas, close to the river mouths which are the primary suppliers of dissolved nutrients. The Gulf of Lion has a relatively high productivity because it is an area of high vertical mixing, bringing nutrients to the surface waters that can be used by phytoplankton to produce Chlorophyll a.[71]
+
+Primary productivity in the Mediterranean is also marked by an intense seasonal variability. In winter, the strong winds and precipitation[Contradicts statement above that precipitation is low] over the basin generate vertical mixing, bringing nutrients from the deep waters to the surface, where phytoplankton can convert it into biomass.[72] However, in winter, light may be the limiting factor for primary productivity. Between March and April, spring offers the ideal trade-off between light intensity and nutrient concentrations in surface for a spring bloom to occur. In summer, high atmospheric temperatures lead to the warming of the surface waters. The resulting density difference virtually isolates the surface waters from the rest of the water column and nutrient exchanges are limited. As a consequence, primary productivity is very low between June and October.[73][71]
+
+Oceanographic expeditions uncovered a characteristic feature of the Mediterranean Sea biogeochemistry: most of the chlorophyll production does not occur on the surface, but in sub-surface waters between 80 and 200 meters deep.[74] Another key characteristic of the Mediterranean is its high nitrogen-to-phosphorus ratio (N:P). Redfield demonstrated that most of the world's oceans have an average N:P ratio around 16. However, the Mediterranean Sea has an average N:P between 24 and 29, which translates a widespread phosphorus limitation.[clarification needed][75][76][77][78]
+
+Because of its low productivity, plankton assemblages in the Mediterranean Sea are dominated by small organisms such as picophytoplankton and bacteria.[79][80]
+
+The geologic history of the Mediterranean Sea is complex. Underlain by oceanic crust, the sea basin was once thought to be a tectonic remnant of the ancient Tethys Ocean; it is now known to be a structurally younger basin, called the Neotethys, which was first formed by the convergence of the African and Eurasian plates during the Late Triassic and Early Jurassic. Because it is a near-landlocked body of water in a normally dry climate, the Mediterranean is subject to intensive evaporation and the precipitation of evaporites. The Messinian salinity crisis started about six million years ago (mya) when the Mediterranean became landlocked, and then essentially dried up. There are salt deposits accumulated on the bottom of the basin of more than a million cubic kilometres—in some places more than three kilometres thick.[81][82]
+
+Scientists estimate that the sea was last filled about 5.3 million years ago (mya) in less than two years by the Zanclean flood. Water poured in from the Atlantic Ocean through a newly breached gateway now called the Strait of Gibraltar at an estimated rate of about three orders of magnitude (one thousand times) larger than the current flow of the Amazon River.[83]
+
+The Mediterranean Sea has an average depth of 1,500 m (4,900 ft) and the deepest recorded point is 5,267 m (17,280 ft) in the Calypso Deep in the Ionian Sea. The coastline extends for 46,000 km (29,000 mi). A shallow submarine ridge (the Strait of Sicily) between the island of Sicily and the coast of Tunisia divides the sea in two main subregions: the Western Mediterranean, with an area of about 850,000 km2 (330,000 mi2); and the Eastern Mediterranean, of about 1.65 million km2 (640,000 mi2). Coastal areas have submarine karst springs or vruljas, which discharge pressurised groundwater into the water from below the surface; the discharge water is usually fresh, and sometimes may be thermal.[84][85]
+
+The Mediterranean basin and sea system was established by the ancient African-Arabian continent colliding with the Eurasian continent. As Africa-Arabia drifted northward, it closed over the ancient Tethys Ocean which had earlier separated the two supercontinents Laurasia and Gondwana.
+At about that time in the middle Jurassic period (roughly 170 million years ago[dubious  – discuss]) a much smaller sea basin, dubbed the Neotethys, was formed shortly before the Tethys Ocean closed at its western (Arabian) end. The broad line of collisions pushed up a very long system of mountains from the Pyrenees in Spain to the Zagros Mountains in Iran in an episode of mountain-building tectonics known as the Alpine orogeny. The Neotethys grew larger during the episodes of collisions (and associated foldings and subductions) that occurred during the Oligocene and Miocene epochs (34 to 5.33 mya); see animation: Africa-Arabia colliding with Eurasia. Accordingly, the Mediterranean basin consists of several stretched tectonic plates in subduction which are the foundation of the eastern part of the Mediterranean Sea. Various zones of subduction contain the highest oceanic ridges, east of the Ionian Sea and south of the Aegean. The Central Indian Ridge runs east of the Mediterranean Sea south-east across the in-between[clarification needed] of Africa and the Arabian Peninsula into the Indian Ocean.
+
+During Mesozoic and Cenozoic times, as the northwest corner of Africa converged on Iberia, it lifted the Betic-Rif mountain belts across southern Iberia and northwest Africa. There the development of the intramontane Betic and Rif basins created two roughly-parallel marine gateways between the Atlantic Ocean and the Mediterranean Sea. Dubbed the Betic and Rifian corridors, they gradually closed during the middle and late Miocene: perhaps several times.[86] In the late Miocene the closure of the Betic Corridor triggered the so-called "Messinian salinity crisis" (MSC), when the Mediterranean almost entirely dried out. The start of the MSC was recently estimated astronomically at 5.96 mya, and it persisted for some 630,000 years until about 5.3 mya;[87] see Animation: Messinian salinity crisis, at right.
+
+After the initial drawdown[clarification needed] and re-flooding, there followed more episodes—the total number is debated—of sea drawdowns and re-floodings for the duration of the MSC. It ended when the Atlantic Ocean last re-flooded the basin—creating the Strait of Gibraltar and causing the Zanclean flood—at the end of the Miocene (5.33 mya). Some research has suggested that a desiccation-flooding-desiccation cycle may have repeated several times, which could explain several events of large amounts of salt deposition.[88][89] Recent studies, however, show that repeated desiccation and re-flooding is unlikely from a geodynamic point of view.[90][91]
+
+The present-day Atlantic gateway, the Strait of Gibraltar, originated in the early Pliocene via the Zanclean Flood. As mentioned, there were two earlier gateways: the Betic Corridor across southern Spain and the Rifian Corridor across northern Morocco. The Betic closed about 6 mya, causing the Messinian salinity crisis (MSC); the Rifian or possibly both gateways closed during the earlier Tortonian times, causing a "Tortonian salinity crisis" (from 11.6 to 7.2 mya), long before the MSC and lasting much longer. Both "crises" resulted in broad connections between the mainlands of Africa and Europe, which allowed migrations of flora and fauna—especially large mammals including primates—between the two continents. The Vallesian crisis indicates a typical extinction and replacement of mammal species in Europe during Tortonian times following climatic upheaval and overland migrations of new species:[92] see Animation: Messinian salinity crisis (and mammal migrations), at right.
+
+The almost complete enclosure of the Mediterranean basin has enabled the oceanic gateways to dominate seawater circulation and the environmental evolution of the sea and basin. Circulation patterns are also affected by several other factors—including climate, bathymetry, and water chemistry and temperature—which are interactive and can induce precipitation of evaporites. Deposits of evaporites accumulated earlier in the nearby Carpathian foredeep during the Middle Miocene, and the adjacent Red Sea Basin (during the Late Miocene), and in the whole Mediterranean basin (during the MSC and the Messinian age). Many diatomites are found underneath the evaporite deposits, suggesting a connection between their[clarification needed] formations.
+
+Today, evaporation of surface seawater (output) is more than the supply (input) of fresh water by precipitation and coastal drainage systems, causing the salinity of the Mediterranean to be much higher than that of the Atlantic—so much so that the saltier Mediterranean waters sink below the waters incoming from the Atlantic, causing a two-layer flow across the Strait of Gibraltar: that is, an outflow submarine current of warm saline Mediterranean water, counterbalanced by an inflow surface current of less saline cold oceanic water from the Atlantic. In the 1920s, Herman Sörgel proposed the building of a hydroelectric dam (the Atlantropa project) across the Straits, using the inflow current to provide a large amount of hydroelectric energy. The underlying energy grid was also intended to support a political union between Europe and, at least, the Maghreb part of Africa (compare Eurafrika for the later impact and Desertec for a later project with some parallels in the planned grid).[93]
+
+The end of the Miocene also marked a change in the climate of the Mediterranean basin. Fossil evidence from that period reveals that the larger basin had a humid subtropical climate with rainfall in the summer supporting laurel forests. The shift to a "Mediterranean climate" occurred largely within the last three million years (the late Pliocene epoch) as summer rainfall decreased. The subtropical laurel forests retreated; and even as they persisted on the islands of Macaronesia off the Atlantic coast of Iberia and North Africa, the present Mediterranean vegetation evolved, dominated by coniferous trees and sclerophyllous trees and shrubs with small, hard, waxy leaves that prevent moisture loss in the dry summers. Much of these forests and shrublands have been altered beyond recognition by thousands of years of human habitation. There are now very few relatively intact natural areas in what was once a heavily wooded region.
+
+Because of its latitude and its land-locked position, the Mediterranean is especially sensitive to astronomically induced climatic variations, which are well documented in its sedimentary record. Since the Mediterranean is subject to the deposition of eolian dust from the Sahara during dry periods, whereas riverine detrital input prevails during wet ones, the Mediterranean marine sapropel-bearing sequences provide high-resolution climatic information. These data have been employed in reconstructing astronomically calibrated time scales for the last 9 Ma of the Earth's history, helping to constrain the time of past geomagnetic reversals.[94] Furthermore, the exceptional accuracy of these paleoclimatic records has improved our knowledge of the Earth's orbital variations in the past.
+
+Unlike the vast multidirectional ocean currents in open oceans within their respective oceanic zones; biodiversity in the Mediterranean Sea is that of a stable one due to the subtle but strong locked nature of currents which affects favorably, even the smallest macroscopic type of volcanic life form. The stable marine ecosystem of the Mediterranean Sea and sea temperature provides a nourishing environment for life in the deep sea to flourish while assuring a balanced aquatic ecosystem excluded from any external deep oceanic factors. It is estimated that there are more than 17,000 marine species in the Mediterranean Sea with generally higher marine biodiversity in coastal areas, continental shelves, and decreases with depth.[95]
+
+As a result of the drying of the sea during the Messinian salinity crisis,[96] the marine biota of the Mediterranean are derived primarily from the Atlantic Ocean. The North Atlantic is considerably colder and more nutrient-rich than the Mediterranean, and the marine life of the Mediterranean has had to adapt to its differing conditions in the five million years since the basin was reflooded.
+
+The Alboran Sea is a transition zone between the two seas, containing a mix of Mediterranean and Atlantic species. The Alboran Sea has the largest population of bottlenose dolphins in the Western Mediterranean, is home to the last population of harbour porpoises in the Mediterranean, and is the most important feeding grounds for loggerhead sea turtles in Europe. The Alboran Sea also hosts important commercial fisheries, including sardines and swordfish. The Mediterranean monk seals live in the Aegean Sea in Greece. In 2003, the World Wildlife Fund raised concerns about the widespread drift net fishing endangering populations of dolphins, turtles, and other marine animals such as the spiny squat lobster.
+
+There was a resident population of killer whale in the Mediterranean until the 1980s, when they went extinct, probably due to long term PCB exposure. There are still annual sightings of killer whale vagrants.[97]
+
+For 4,000 years, human activity has transformed most parts of Mediterranean Europe, and the "humanisation of the landscape" overlapped with the appearance of the present Mediterranean climate.[98] The image of a simplistic, environmental determinist notion of a Mediterranean paradise on Earth in antiquity, which was destroyed by later civilisations, dates back to at least the 18th century and was for centuries fashionable in archaeological and historical circles. Based on a broad variety of methods, e.g. historical documents, analysis of trade relations, floodplain sediments, pollen, tree-ring and further archaeometric analyses and population studies, Alfred Thomas Grove's and Oliver Rackham's work on "The Nature of Mediterranean Europe" challenges this common wisdom of a Mediterranean Europe as a "Lost Eden", a formerly fertile and forested region, that had been progressively degraded and desertified by human mismanagement.[98] The belief stems more from the failure of the recent landscape to measure up to the imaginary past of the classics as idealised by artists, poets and scientists of the early modern Enlightenment.[98]
+
+The historical evolution of climate, vegetation and landscape in southern Europe from prehistoric times to the present is much more complex and underwent various changes. For example, some of the deforestation had already taken place before the Roman age. While in the Roman age large enterprises such as the latifundia took effective care of forests and agriculture, the largest depopulation effects came with the end of the empire. Some[who?] assume that the major deforestation took place in modern times—the later usage patterns were also quite different e.g. in southern and northern Italy. Also, the climate has usually been unstable and there is evidence of various ancient and modern "Little Ice Ages",[99] and plant cover accommodated to various extremes and became resilient to various patterns of human activity.[98]
+
+Human activity was therefore not the cause of climate change but followed it.[98] The wide ecological diversity typical of Mediterranean Europe is predominantly based on human behavior, as it is and has been closely related human usage patterns.[98] The diversity range[clarification needed] was enhanced by the widespread exchange and interaction of the longstanding and highly diverse local agriculture, intense transport and trade relations, and the interaction with settlements, pasture and other land use. The greatest human-induced changes, however, came after World War II, in line with the "1950s syndrome"[100] as rural populations throughout the region abandoned traditional subsistence economies. Grove and Rackham suggest that the locals left the traditional agricultural patterns and instead became scenery-setting agents[clarification needed] for tourism. This resulted in more uniform, large-scale formations[of what?].[98] Among further current important threats to Mediterranean landscapes are overdevelopment of coastal areas, abandonment of mountains and, as mentioned, the loss of variety via the reduction of traditional agricultural occupations.[98]
+
+The region has a variety of geological hazards which have closely interacted with human activity and land use patterns. Among others, in the eastern Mediterranean, the Thera eruption, dated to the 17th or 16th century BC, caused a large tsunami that some experts hypothesise devastated the Minoan civilisation on the nearby island of Crete, further leading some to believe that this may have been the catastrophe that inspired the Atlantis legend.[101] Mount Vesuvius is the only active volcano on the European mainland, while others, Mount Etna and Stromboli, are on neighbouring islands. The region around Vesuvius including the Phlegraean Fields Caldera west of Naples are quite active[102] and constitute the most densely populated volcanic region in the world where an eruptive event may occur within decades.[103]
+
+Vesuvius itself is regarded as quite dangerous due to a tendency towards explosive (Plinian) eruptions.[104] It is best known for its eruption in AD 79 that led to the burying and destruction of the Roman cities of Pompeii and Herculaneum.
+
+The large experience[clarification needed] of member states and regional authorities has led to exchange[of what?] on the international level with cooperation of NGOs, states, regional and municipality authorities and private persons.[105] The Greek–Turkish earthquake diplomacy is a quite positive example of natural hazards leading to improved relations between traditional rivals in the region after earthquakes in İzmir and Athens in 1999. The European Union Solidarity Fund (EUSF) was set up to respond to major natural disasters and express European solidarity to disaster-stricken regions within all of Europe.[106] The largest amount of funding requests in the EU relates to forest fires, followed by floods and earthquakes. Forest fires, whether man made or natural, are a frequent and dangerous hazard in the Mediterranean region.[105] Tsunamis are also an often underestimated hazard in the region. For example, the 1908 Messina earthquake and tsunami took more than 123,000 lives in Sicily and Calabria and was among the most deadly natural disasters in modern Europe.
+
+The opening of the Suez Canal in 1869 created the first salt-water passage between the Mediterranean and the Red Sea. The Red Sea is higher than the Eastern Mediterranean, so the canal functions as a tidal strait that pours Red Sea water into the Mediterranean. The Bitter Lakes, which are hyper-saline natural lakes that form part of the canal, blocked the migration of Red Sea species into the Mediterranean for many decades, but as the salinity of the lakes gradually equalised with that of the Red Sea, the barrier to migration was removed, and plants and animals from the Red Sea have begun to colonise the Eastern Mediterranean. The Red Sea is generally saltier and more nutrient-poor than the Atlantic, so the Red Sea species have advantages over Atlantic species in the salty and nutrient-poor Eastern Mediterranean. Accordingly, Red Sea species invade the Mediterranean biota, and not vice versa; this phenomenon is known as the Lessepsian migration (after Ferdinand de Lesseps, the French engineer) or Erythrean ("red") invasion. The construction of the Aswan High Dam across the Nile River in the 1960s reduced the inflow of freshwater and nutrient-rich silt from the Nile into the Eastern Mediterranean, making conditions there even more like the Red Sea and worsening the impact of the invasive species.
+
+Invasive species have become a major component of the Mediterranean ecosystem and have serious impacts on the Mediterranean ecology, endangering many local and endemic Mediterranean species. A first look at some groups of exotic species shows that more than 70% of the non-indigenous decapods and about 63% of the exotic fishes occurring in the Mediterranean are of Indo-Pacific origin,[107] introduced into the Mediterranean through the Suez Canal. This makes the Canal the first pathway of arrival of alien species into the Mediterranean. The impacts of some Lessepsian species have proven to be considerable, mainly in the Levantine basin of the Mediterranean, where they are replacing native species and becoming a familiar sight.
+
+According to the International Union for Conservation of Nature definition, as well as Convention on Biological Diversity (CBD) and Ramsar Convention terminologies, they are alien species, as they are non-native (non-indigenous) to the Mediterranean Sea, and they are outside their normal area of distribution which is the Indo-Pacific region. When these species succeed in establishing populations in the Mediterranean Sea, compete with and begin to replace native species they are "Alien Invasive Species", as they are an agent of change and a threat to the native biodiversity. In the context of CBD, "introduction" refers to the movement by human agency, indirect or direct, of an alien species outside of its natural range (past or present). The Suez Canal, being an artificial (man made) canal, is a human agency. Lessepsian migrants are therefore "introduced" species (indirect, and unintentional). Whatever wording is chosen, they represent a threat to the native Mediterranean biodiversity, because they are non-indigenous to this sea. In recent years, the Egyptian government's announcement of its intentions to deepen and widen the canal have raised concerns from marine biologists, fearing that such an act will only worsen the invasion of Red Sea species into the Mediterranean, and lead to even more species passing through the canal.[108]
+
+In recent decades, the arrival of exotic species from the tropical Atlantic has become noticeable. Whether this reflects an expansion of the natural area of these species that now enter the Mediterranean through the Gibraltar strait, because of a warming trend of the water caused by global warming; or an extension of the maritime traffic; or is simply the result of a more intense scientific investigation, is still an open question. While not as intense as the "Lessepsian" movement, the process may be of scientific interest and may therefore[non sequitur] warrant increased levels of monitoring.[citation needed]
+
+By 2100 the overall level of the Mediterranean could rise between 3 to 61 cm (1.2 to 24.0 in) as a result of the effects of climate change.[109] This could have adverse effects on populations across the Mediterranean:
+
+Coastal ecosystems also appear to be threatened by sea level rise, especially enclosed seas such as the Baltic, the Mediterranean and the Black Sea. These seas have only small and primarily east–west movement corridors, which may restrict northward displacement of organisms in these areas.[113] Sea level rise for the next century (2100) could be between 30 cm (12 in) and 100 cm (39 in) and temperature shifts of a mere 0.05–0.1 °C in the deep sea are sufficient to induce significant changes in species richness and functional diversity.[114]
+
+Pollution in this region has been extremely high in recent years.[when?] The United Nations Environment Programme has estimated that 650,000,000 t (720,000,000 short tons) of sewage, 129,000 t (142,000 short tons) of mineral oil, 60,000 t (66,000 short tons) of mercury, 3,800 t (4,200 short tons) of lead and 36,000 t (40,000 short tons) of phosphates are dumped into the Mediterranean each year.[115] The Barcelona Convention aims to 'reduce pollution in the Mediterranean Sea and protect and improve the marine environment in the area, thereby contributing to its sustainable development.'[116]
+Many marine species have been almost wiped out because of the sea's pollution. One of them is the Mediterranean monk seal which is considered to be among the world's most endangered marine mammals.[117]
+
+The Mediterranean is also plagued by marine debris. A 1994 study of the seabed using trawl nets around the coasts of Spain, France and Italy reported a particularly high mean concentration of debris; an average of 1,935 items per km2. Plastic debris accounted for 76%, of which 94% was plastic bags.[118]
+
+Some of the world's busiest shipping routes are in the Mediterranean Sea. It is estimated that approximately 220,000 merchant vessels of more than 100 tonnes cross the Mediterranean Sea each year—about one third of the world's total merchant shipping. These ships often carry hazardous cargo, which if lost would result in severe damage to the marine environment.
+
+The discharge of chemical tank washings and oily wastes also represent a significant source of marine pollution. The Mediterranean Sea constitutes 0.7% of the global water surface and yet receives 17% of global marine oil pollution. It is estimated that every year between 100,000 t (98,000 long tons) and 150,000 t (150,000 long tons) of crude oil are deliberately released into the sea from shipping activities.
+
+Approximately 370,000,000 t (360,000,000 long tons) of oil are transported annually in the Mediterranean Sea (more than 20% of the world total), with around 250–300 oil tankers crossing the sea every day. Accidental oil spills happen frequently with an average of 10 spills per year. A major oil spill could occur at any time in any part of the Mediterranean.[114]
+
+Tourism is one of the most important sources of income for many Mediterranean countries, despite the man-made geopolitical conflicts[clarification needed] in the region. The countries have tried to extinguish rising man-made chaotic zones[clarification needed] that might affect the region's economies and societies in neighboring coastal countries, and shipping routes. Naval and rescue components in the Mediterranean Sea are considered to be among the best[citation needed] due to the rapid cooperation between various naval fleets. Unlike the vast open oceans, the sea's closed position facilitates effective naval and rescue missions[citation needed], considered the safest[citation needed] and regardless of[clarification needed] any man-made or natural disaster.
+
+Tourism is a source of income for small coastal communities, including islands, independent of urban centers. However, tourism has also played major role in the degradation of the coastal and marine environment. Rapid development has been encouraged by Mediterranean governments to support the large numbers of tourists visiting the region; but this has caused serious disturbance to marine habitats by erosion and pollution in many places along the Mediterranean coasts.
+
+Tourism often concentrates in areas of high natural wealth[clarification needed], causing a serious threat to the habitats of endangered species such as sea turtles and monk seals. Reductions in natural wealth may reduce the incentive for tourists to visit.[114]
+
+Fish stock levels in the Mediterranean Sea are alarmingly low. The European Environment Agency says that more than 65% of all fish stocks in the region are outside safe biological limits and the United Nations Food and Agriculture Organisation, that some of the most important fisheries—such as albacore and bluefin tuna, hake, marlin, swordfish, red mullet and sea bream—are threatened.[date missing]
+
+There are clear indications that catch size and quality have declined, often dramatically, and in many areas larger and longer-lived species have disappeared entirely from commercial catches.
+
+Large open water fish like tuna have been a shared fisheries resource for thousands of years but the stocks are now dangerously low. In 1999, Greenpeace published a report revealing that the amount of bluefin tuna in the Mediterranean had decreased by over 80% in the previous 20 years and government scientists warn that without immediate action the stock will collapse.
+
+Beach of Hammamet, Tunisia
+
+The beach of la Courtade in the Îles d'Hyères, France
+
+Sardinia's south coast, Italy
+
+Pretty Bay, Malta
+
+Panoramic view of Piran, Slovenia
+
+Panoramic view of Cavtat, Croatia
+
+View of Neum, Bosnia and Herzegovina
+
+A view of Sveti Stefan, Montenegro
+
+Ksamil Islands, Albania
+
+Navagio, Greece
+
+Marmaris, Turquoise Coast, Turkey
+
+Paphos, Cyprus
+
+Burj Islam Beach, Latakia, Syria
+
+A view of Raouché off the coast of Beirut, Lebanon
+
+A view of Haifa, Israel
+
+Coast of Alexandria, view From Bibliotheca Alexandrina, Egypt
+
+Old city of Ibiza Town, Spain
+
+Les Aiguades near Béjaïa, Algeria
+
+El Jebha, a port town in Morocco
+
+Europa Point, Gibraltar
+
+Panoramic view of La Condamine, Monaco
+
+Sunset at the Deir al-Balah beach, Gaza Strip

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+In Greek mythology, Medusa (/mɪˈdjuːzə, -sə/; Μέδουσα "guardian, protectress")[1] also called Gorgo, was one of the three  monstrous Gorgons, generally described as winged human females with living venomous snakes in place of hair. Those who gazed into her eyes would turn to stone. Most sources describe her as the daughter of Phorcys and Ceto,[2] although the author Hyginus makes her the daughter of Gorgon and Ceto.[3] According to Hesiod and Aeschylus, she lived and died on an island named Sarpedon, somewhere near Cisthene. The 2nd-century BC novelist Dionysios Skytobrachion puts her somewhere in Libya, where Herodotus had said the Berbers originated her myth, as part of their religion.
+
+Medusa was raped by Poseidon then beheaded by the hero Perseus, who thereafter used her head, which retained its ability to turn onlookers to stone, as a weapon[4] until he gave it to the goddess Athena to place on her shield. In classical antiquity the image of the head of Medusa appeared in the evil-averting device known as the Gorgoneion.
+
+The three Gorgon sisters—Medusa, Stheno, and Euryale—were all children of the ancient marine deities Phorcys (or "Phorkys") and his sister Ceto (or "Keto"), chthonic monsters from an archaic world.  Their genealogy is shared with other sisters, the Graeae, as in Aeschylus's Prometheus Bound, which places both trinities of sisters far off "on Kisthene's dreadful plain":
+
+Near them their sisters three, the Gorgons, winged
+With snakes for hair—hatred of mortal man—
+
+While ancient Greek vase-painters and relief carvers imagined Medusa and her sisters as having monstrous form, sculptors and vase-painters of the fifth century began to envisage her as being beautiful as well as terrifying. In an ode written in 490 BC Pindar already speaks of "fair-cheeked Medusa".[5]
+
+In a late version of the Medusa myth, related by the Roman poet Ovid (Metamorphoses 4.770), Medusa was originally a ravishingly beautiful maiden, "the jealous aspiration of many suitors," but because Poseidon raped Medusa in Athena's temple, Athena transformed Medusa's beautiful hair to serpents and made her face so terrible to behold that the mere sight of it would turn onlookers to stone.[6] In Ovid's telling, Perseus describes Medusa's punishment by Minerva (Athena) as just and well earned.
+
+In most versions of the story, she was beheaded by the hero Perseus, who was sent to fetch her head by King Polydectes of Seriphus because Polydectes wanted to marry Perseus's mother. The gods were well aware of this, and Perseus received help. He received a mirrored shield from Athena, gold, winged sandals from Hermes, a sword from Hephaestus and Hades's helm of invisibility. Since Medusa was the only one of the three Gorgons who was mortal, Perseus was able to slay her while looking at the reflection from the mirrored shield he received from Athena. During that time, Medusa was pregnant by Poseidon. When Perseus beheaded her, Pegasus, a winged horse, and Chrysaor, a giant wielding a golden sword, sprang from her body.[7]
+
+Jane Ellen Harrison argues that "her potency only begins when her head is severed, and that potency resides in the head; she is in a word a mask with a body later appended... the basis of the Gorgoneion is a cultus object, a ritual mask misunderstood."[8]
+
+In the Odyssey xi, Homer does not specifically mention the Gorgon Medusa:
+
+Lest for my daring Persephone the dread,
+From Hades should send up an awful monster's grisly head.
+
+Harrison's translation states "the Gorgon was made out of the terror, not the terror out of the Gorgon."[8]
+
+According to Ovid, in northwest Africa, Perseus flew past the Titan Atlas, who stood holding the sky aloft, and transformed him into stone when he tried to attack him.[9] In a similar manner, the corals of the Red Sea were said to have been formed of Medusa's blood spilled onto seaweed when Perseus laid down the petrifying head beside the shore during his short stay in Ethiopia where he saved and wed his future wife, the lovely princess Andromeda who was the most beautiful woman in the world at that time. Furthermore, the poisonous vipers of the Sahara, in the Argonautica 4.1515, Ovid's Metamorphoses 4.770 and Lucan's Pharsalia 9.820, were said to have grown from spilt drops of her blood. The blood of Medusa also spawned the Amphisbaena (a horned dragon-like creature with a snake-headed tail).
+
+Perseus then flew to Seriphos, where his mother was being forced into marriage with the king, Polydectes, who was turned into stone by the head. Then Perseus gave the Gorgon's head to Athena, who placed it on her shield, the Aegis.[10]
+
+Some classical references refer to three Gorgons; Harrison considered that the tripling of Medusa into a trio of sisters was a secondary feature in the myth:
+
+The triple form is not primitive, it is merely an instance of a general tendency... which makes of each woman goddess a trinity, which has given us the Horae, the Charites, the Semnai, and a host of other triple groups. It is immediately obvious that the Gorgons are not really three but one + two. The two unslain sisters are mere appendages due to custom; the real Gorgon is Medusa.[8]
+
+A number of early classics scholars interpreted the myth of Medusa as a quasi-historical – "based on or reconstructed from an event, custom, style, etc., in the past",[11] or "sublimated" memory of an actual invasion.[12][13]
+
+According to Joseph Campbell:
+
+The legend of Perseus beheading Medusa means, specifically, that "the Hellenes overran the goddess's chief shrines" and "stripped her priestesses of their Gorgon masks", the latter being apotropaic faces worn to frighten away the profane.
+That is to say, there occurred in the early thirteenth century B.C. an actual historic rupture, a sort of sociological trauma, which has been registered in this myth, much as what Freud terms the latent content of a neurosis is registered in the manifest content of a dream: registered yet hidden, registered in the unconscious yet unknown or misconstrued by the conscious mind.[14]
+
+In 1940, Sigmund Freud's "Das Medusenhaupt (Medusa's Head)" was published posthumously. In Freud's interpretation: "To decapitate = to castrate. The terror of Medusa is thus a terror of castration that is linked to the sight of something. Numerous analyses have made us familiar with the occasion for this: it occurs when a boy, who has hitherto been unwilling to believe the threat of castration, catches sight of the female genitals, probably those of an adult, surrounded by hair, and essentially those of his mother."[15] In this perspective the "ravishingly beautiful" Medusa (see above) is the mother remembered in innocence; before the mythic truth of castration dawns on the subject. Classic Medusa, in contrast, is an Oedipal/libidinous symptom. Looking at forbidden mother (in her hair-covered genitals, so to speak) stiffens the subject in illicit desire and freezes him in terror of the Father's retribution. There are no recorded instances of Medusa turning a woman to stone.
+
+Archetypal literary criticism continues to find psychoanalysis useful. Beth Seelig analyzes Medusa's punishment from the aspect of the crime of having been raped rather than having willingly consented in Athena's temple as an outcome of the goddess' unresolved conflicts with her own father, Zeus.[16]
+
+In the 20th century, feminists reassessed Medusa's appearances in literature and in modern culture, including the use of Medusa as a logo by fashion company Versace.[17][18][19][20] The name "Medusa" itself is often used in ways not directly connected to the mythological figure but to suggest the gorgon's abilities or to connote malevolence; despite her origins as a beauty, the name in common usage "came to mean monster."[21] The book Female Rage: Unlocking Its Secrets, Claiming Its Power by Mary Valentis and Anne Devane notes that "When we asked women what female rage looks like to them, it was always Medusa, the snaky-haired monster of myth, who came to mind ... In one interview after another we were told that Medusa is 'the most horrific woman in the world' ... [though] none of the women we interviewed could remember the details of the myth."[22]
+
+Medusa's visage has since been adopted by many women as a symbol of female rage; one of the first publications to express this idea was a feminist journal called Women: A Journal of Liberation in their issue one, volume six for 1978. The cover featured the image of the Gorgon Medusa by Froggi Lupton, which the editors on the inside cover explained "can be a map to guide us through our terrors, through the depths of our anger into the sources of our power as women."[22]
+
+In issue three, Fall 1986 for the magazine Woman of Power an article called Gorgons: A Face for Contemporary Women's Rage, appeared, written by Emily Erwin Culpepper, who wrote that "The Amazon Gorgon face is female fury personified. The Gorgon/Medusa image has been rapidly adopted by large numbers of feminists who recognize her as one face of our own rage."[22] Griselda Pollock analyses the passage from horrorism to compassion in the figure of the Medusa through Adriana Cavarero's philosophy and Bracha Ettinger's art and Matrixial theory.[23]
+
+Elana Dykewomon's 1976 collection of lesbian stories and poems, They Will Know Me by My Teeth, features a drawing of a Gorgon on its cover. Its purpose was to act as a guardian for female power, keeping the book solely in the hands of women. Stephen Wilk, author of Medusa: Solving the Mystery of the Gorgon, questioned Medusa's enduring status among the feminist movement. He believes that one reason for her longevity may be her role as a protector, fearsome and enraged. "Only the Gorgon has the savage, threatening appearance to serve as an immediately recognized symbol of rage and a protector of women's secrets," wrote Wilk.[24]
+
+Even in contemporary pop culture, Medusa has become largely synonymous with feminine rage. Through many of her iterations, Medusa pushes back against a story that seeks to place the male, Perseus, at its center, blameless and heroic. Author Sibylle Baumbach described Medusa as a “multimodal image of intoxication, petrifaction, and luring attractiveness," citing her seductive contemporary representation, as well as her dimensionality, as the reason for her longevity.[25] Elizabeth Johnston's November 2016 Atlantic essay called Medusa the original 'Nasty Woman.' Johnston goes on to say that as Medusa has been repeatedly compared to Clinton during the 2016 presidential election, she proves her merit as an icon, finding relevance even in modern politics. "Medusa has since haunted Western imagination, materializing whenever male authority feels threatened by female agency," writes Johnston.[26] Beyond that, Medusa's story is, Johnston argues, a rape narrative. A story of victim blaming, one that she says sounds all too familiar in a current American context.
+
+Medusa is widely known as a monstrous creature with snakes in her hair whose gaze turns men to stone. Through the lens of theology, film, art, and feminist literature, my students and I map how her meaning has shifted over time and across cultures. In so doing, we unravel a familiar narrative thread: In Western culture, strong women have historically been imagined as threats requiring male conquest and control, and Medusa herself has long been the go-to figure for those seeking to demonize female authority.
+
+The Medusa story has also been interpreted in contemporary art as a classic case of rape-victim blaming, by the Goddess Athena.  Inspired by the #metoo movement, contemporary figurative artist Judy Takács returns Medusa's beauty along with a hashtag stigmata in her portrait, #Me(dusa)too.[27]
+
+Feminist theorist Hélène Cixous famously tackled the myth in her essay "The Laugh of the Medusa." She argues that men's retelling of the narrative turned Medusa into a monster because they feared female desire. "The Laugh of the Medusa" is largely a call to arms, urging women to reclaim their identity through writing as she rejects the patriarchal society of Western culture. Cixous calls writing "an act which will not only 'realize' the decensored relation of woman to her sexuality, to her womanly being, giving her access to her native strength; it will give her back her goods, her pleasures, her organs, her immense bodily territories which have been kept under seal." She claims "we must kill the false woman who is preventing the live one from breathing. Inscribe the breath of the whole woman."[28]  Cixous wants to destroy the phallogocentric system, and to empower women's bodies and language.[29] "You only have to look at the Medusa straight on to see her," writes Cixous. "And she's not deadly. She's beautiful and she's laughing."[30]
+
+Medusa has sometimes appeared as representing notions of scientific determinism and nihilism, especially in contrast with romantic idealism.[31][32] In this interpretation of Medusa, attempts to avoid looking into her eyes represent avoiding the ostensibly depressing reality that the universe is meaningless. Jack London uses Medusa in this way in his novel The Mutiny of the Elsinore:[33]
+
+I cannot help remembering a remark of De Casseres. It was over the wine in Mouquin's. Said he: "The profoundest instinct in man is to war against the truth; that is, against the Real. He shuns facts from his infancy. His life is a perpetual evasion. Miracle, chimera and to-morrow keep him alive. He lives on fiction and myth. It is the Lie that makes him free. Animals alone are given the privilege of lifting the veil of Isis; men dare not. The animal, awake, has no fictional escape from the Real because he has no imagination. Man, awake, is compelled to seek a perpetual escape into Hope, Belief, Fable, Art, God, Socialism, Immortality, Alcohol, Love. From Medusa-Truth he makes an appeal to Maya-Lie."
+
+Medusa has been depicted in several works of art, including:
+
+Medusa remained a common theme in art in the nineteenth century, when her myth was retold in Thomas Bulfinch's Mythology. Edward Burne-Jones' Perseus Cycle of paintings and a drawing by Aubrey Beardsley gave way to the twentieth century works of Paul Klee, John Singer Sargent, Pablo Picasso, Pierre et Gilles, and Auguste Rodin's bronze sculpture The Gates of Hell.[34]
+
+The most influential depiction of Medusa in film is arguably the stop motion animation created by Ray Harryhausen for Clash of the Titans (1981). As well has having snakes for hair, she was given a serpent-like body and rattlesnake-like tail. The model was one Harryhausen’s most complex and in 2020 it was voted third favourite among his many creations.
+
+The head of Medusa is featured on some regional symbols. One example is that of the flag and emblem of Sicily, together with the three legged trinacria. The inclusion of Medusa in the center implies the protection of the goddess Athena, who wore the Gorgon's likeness on her aegis, as said above. Another example is the coat of arms of Dohalice village in the Czech Republic.
+
+Municipal coat of arms of Dohalice village, Hradec Králové District, Czech Republic
+
+Flag of Sicily
+
+Ceremonial French military uniform belt of World War I
+
+Medusa is honored in the following scientific names:[35]
+
+The petrifying image of Medusa makes an instantly recognizable feature in popular culture. Medusa has been featured in several works of fiction, including video games, movies, cartoons and books. In particular, the designer Versace's symbol is reflected through the Medusa-head symbol. It was chosen because she represents beauty, art, and philosophy.[37]
+
+The motive of the Medusa has also had an appearance in some of the modern songs. One of the most notable examples is the song 'Medusa' by the American thrash metal band Anthrax, which describes this demonic creature and is the ninth track on their second studio album Spreading the Disease.

en/3759.html.txt

@@ -0,0 +1,82 @@
+In Greek mythology, Medusa (/mɪˈdjuːzə, -sə/; Μέδουσα "guardian, protectress")[1] also called Gorgo, was one of the three  monstrous Gorgons, generally described as winged human females with living venomous snakes in place of hair. Those who gazed into her eyes would turn to stone. Most sources describe her as the daughter of Phorcys and Ceto,[2] although the author Hyginus makes her the daughter of Gorgon and Ceto.[3] According to Hesiod and Aeschylus, she lived and died on an island named Sarpedon, somewhere near Cisthene. The 2nd-century BC novelist Dionysios Skytobrachion puts her somewhere in Libya, where Herodotus had said the Berbers originated her myth, as part of their religion.
+
+Medusa was raped by Poseidon then beheaded by the hero Perseus, who thereafter used her head, which retained its ability to turn onlookers to stone, as a weapon[4] until he gave it to the goddess Athena to place on her shield. In classical antiquity the image of the head of Medusa appeared in the evil-averting device known as the Gorgoneion.
+
+The three Gorgon sisters—Medusa, Stheno, and Euryale—were all children of the ancient marine deities Phorcys (or "Phorkys") and his sister Ceto (or "Keto"), chthonic monsters from an archaic world.  Their genealogy is shared with other sisters, the Graeae, as in Aeschylus's Prometheus Bound, which places both trinities of sisters far off "on Kisthene's dreadful plain":
+
+Near them their sisters three, the Gorgons, winged
+With snakes for hair—hatred of mortal man—
+
+While ancient Greek vase-painters and relief carvers imagined Medusa and her sisters as having monstrous form, sculptors and vase-painters of the fifth century began to envisage her as being beautiful as well as terrifying. In an ode written in 490 BC Pindar already speaks of "fair-cheeked Medusa".[5]
+
+In a late version of the Medusa myth, related by the Roman poet Ovid (Metamorphoses 4.770), Medusa was originally a ravishingly beautiful maiden, "the jealous aspiration of many suitors," but because Poseidon raped Medusa in Athena's temple, Athena transformed Medusa's beautiful hair to serpents and made her face so terrible to behold that the mere sight of it would turn onlookers to stone.[6] In Ovid's telling, Perseus describes Medusa's punishment by Minerva (Athena) as just and well earned.
+
+In most versions of the story, she was beheaded by the hero Perseus, who was sent to fetch her head by King Polydectes of Seriphus because Polydectes wanted to marry Perseus's mother. The gods were well aware of this, and Perseus received help. He received a mirrored shield from Athena, gold, winged sandals from Hermes, a sword from Hephaestus and Hades's helm of invisibility. Since Medusa was the only one of the three Gorgons who was mortal, Perseus was able to slay her while looking at the reflection from the mirrored shield he received from Athena. During that time, Medusa was pregnant by Poseidon. When Perseus beheaded her, Pegasus, a winged horse, and Chrysaor, a giant wielding a golden sword, sprang from her body.[7]
+
+Jane Ellen Harrison argues that "her potency only begins when her head is severed, and that potency resides in the head; she is in a word a mask with a body later appended... the basis of the Gorgoneion is a cultus object, a ritual mask misunderstood."[8]
+
+In the Odyssey xi, Homer does not specifically mention the Gorgon Medusa:
+
+Lest for my daring Persephone the dread,
+From Hades should send up an awful monster's grisly head.
+
+Harrison's translation states "the Gorgon was made out of the terror, not the terror out of the Gorgon."[8]
+
+According to Ovid, in northwest Africa, Perseus flew past the Titan Atlas, who stood holding the sky aloft, and transformed him into stone when he tried to attack him.[9] In a similar manner, the corals of the Red Sea were said to have been formed of Medusa's blood spilled onto seaweed when Perseus laid down the petrifying head beside the shore during his short stay in Ethiopia where he saved and wed his future wife, the lovely princess Andromeda who was the most beautiful woman in the world at that time. Furthermore, the poisonous vipers of the Sahara, in the Argonautica 4.1515, Ovid's Metamorphoses 4.770 and Lucan's Pharsalia 9.820, were said to have grown from spilt drops of her blood. The blood of Medusa also spawned the Amphisbaena (a horned dragon-like creature with a snake-headed tail).
+
+Perseus then flew to Seriphos, where his mother was being forced into marriage with the king, Polydectes, who was turned into stone by the head. Then Perseus gave the Gorgon's head to Athena, who placed it on her shield, the Aegis.[10]
+
+Some classical references refer to three Gorgons; Harrison considered that the tripling of Medusa into a trio of sisters was a secondary feature in the myth:
+
+The triple form is not primitive, it is merely an instance of a general tendency... which makes of each woman goddess a trinity, which has given us the Horae, the Charites, the Semnai, and a host of other triple groups. It is immediately obvious that the Gorgons are not really three but one + two. The two unslain sisters are mere appendages due to custom; the real Gorgon is Medusa.[8]
+
+A number of early classics scholars interpreted the myth of Medusa as a quasi-historical – "based on or reconstructed from an event, custom, style, etc., in the past",[11] or "sublimated" memory of an actual invasion.[12][13]
+
+According to Joseph Campbell:
+
+The legend of Perseus beheading Medusa means, specifically, that "the Hellenes overran the goddess's chief shrines" and "stripped her priestesses of their Gorgon masks", the latter being apotropaic faces worn to frighten away the profane.
+That is to say, there occurred in the early thirteenth century B.C. an actual historic rupture, a sort of sociological trauma, which has been registered in this myth, much as what Freud terms the latent content of a neurosis is registered in the manifest content of a dream: registered yet hidden, registered in the unconscious yet unknown or misconstrued by the conscious mind.[14]
+
+In 1940, Sigmund Freud's "Das Medusenhaupt (Medusa's Head)" was published posthumously. In Freud's interpretation: "To decapitate = to castrate. The terror of Medusa is thus a terror of castration that is linked to the sight of something. Numerous analyses have made us familiar with the occasion for this: it occurs when a boy, who has hitherto been unwilling to believe the threat of castration, catches sight of the female genitals, probably those of an adult, surrounded by hair, and essentially those of his mother."[15] In this perspective the "ravishingly beautiful" Medusa (see above) is the mother remembered in innocence; before the mythic truth of castration dawns on the subject. Classic Medusa, in contrast, is an Oedipal/libidinous symptom. Looking at forbidden mother (in her hair-covered genitals, so to speak) stiffens the subject in illicit desire and freezes him in terror of the Father's retribution. There are no recorded instances of Medusa turning a woman to stone.
+
+Archetypal literary criticism continues to find psychoanalysis useful. Beth Seelig analyzes Medusa's punishment from the aspect of the crime of having been raped rather than having willingly consented in Athena's temple as an outcome of the goddess' unresolved conflicts with her own father, Zeus.[16]
+
+In the 20th century, feminists reassessed Medusa's appearances in literature and in modern culture, including the use of Medusa as a logo by fashion company Versace.[17][18][19][20] The name "Medusa" itself is often used in ways not directly connected to the mythological figure but to suggest the gorgon's abilities or to connote malevolence; despite her origins as a beauty, the name in common usage "came to mean monster."[21] The book Female Rage: Unlocking Its Secrets, Claiming Its Power by Mary Valentis and Anne Devane notes that "When we asked women what female rage looks like to them, it was always Medusa, the snaky-haired monster of myth, who came to mind ... In one interview after another we were told that Medusa is 'the most horrific woman in the world' ... [though] none of the women we interviewed could remember the details of the myth."[22]
+
+Medusa's visage has since been adopted by many women as a symbol of female rage; one of the first publications to express this idea was a feminist journal called Women: A Journal of Liberation in their issue one, volume six for 1978. The cover featured the image of the Gorgon Medusa by Froggi Lupton, which the editors on the inside cover explained "can be a map to guide us through our terrors, through the depths of our anger into the sources of our power as women."[22]
+
+In issue three, Fall 1986 for the magazine Woman of Power an article called Gorgons: A Face for Contemporary Women's Rage, appeared, written by Emily Erwin Culpepper, who wrote that "The Amazon Gorgon face is female fury personified. The Gorgon/Medusa image has been rapidly adopted by large numbers of feminists who recognize her as one face of our own rage."[22] Griselda Pollock analyses the passage from horrorism to compassion in the figure of the Medusa through Adriana Cavarero's philosophy and Bracha Ettinger's art and Matrixial theory.[23]
+
+Elana Dykewomon's 1976 collection of lesbian stories and poems, They Will Know Me by My Teeth, features a drawing of a Gorgon on its cover. Its purpose was to act as a guardian for female power, keeping the book solely in the hands of women. Stephen Wilk, author of Medusa: Solving the Mystery of the Gorgon, questioned Medusa's enduring status among the feminist movement. He believes that one reason for her longevity may be her role as a protector, fearsome and enraged. "Only the Gorgon has the savage, threatening appearance to serve as an immediately recognized symbol of rage and a protector of women's secrets," wrote Wilk.[24]
+
+Even in contemporary pop culture, Medusa has become largely synonymous with feminine rage. Through many of her iterations, Medusa pushes back against a story that seeks to place the male, Perseus, at its center, blameless and heroic. Author Sibylle Baumbach described Medusa as a “multimodal image of intoxication, petrifaction, and luring attractiveness," citing her seductive contemporary representation, as well as her dimensionality, as the reason for her longevity.[25] Elizabeth Johnston's November 2016 Atlantic essay called Medusa the original 'Nasty Woman.' Johnston goes on to say that as Medusa has been repeatedly compared to Clinton during the 2016 presidential election, she proves her merit as an icon, finding relevance even in modern politics. "Medusa has since haunted Western imagination, materializing whenever male authority feels threatened by female agency," writes Johnston.[26] Beyond that, Medusa's story is, Johnston argues, a rape narrative. A story of victim blaming, one that she says sounds all too familiar in a current American context.
+
+Medusa is widely known as a monstrous creature with snakes in her hair whose gaze turns men to stone. Through the lens of theology, film, art, and feminist literature, my students and I map how her meaning has shifted over time and across cultures. In so doing, we unravel a familiar narrative thread: In Western culture, strong women have historically been imagined as threats requiring male conquest and control, and Medusa herself has long been the go-to figure for those seeking to demonize female authority.
+
+The Medusa story has also been interpreted in contemporary art as a classic case of rape-victim blaming, by the Goddess Athena.  Inspired by the #metoo movement, contemporary figurative artist Judy Takács returns Medusa's beauty along with a hashtag stigmata in her portrait, #Me(dusa)too.[27]
+
+Feminist theorist Hélène Cixous famously tackled the myth in her essay "The Laugh of the Medusa." She argues that men's retelling of the narrative turned Medusa into a monster because they feared female desire. "The Laugh of the Medusa" is largely a call to arms, urging women to reclaim their identity through writing as she rejects the patriarchal society of Western culture. Cixous calls writing "an act which will not only 'realize' the decensored relation of woman to her sexuality, to her womanly being, giving her access to her native strength; it will give her back her goods, her pleasures, her organs, her immense bodily territories which have been kept under seal." She claims "we must kill the false woman who is preventing the live one from breathing. Inscribe the breath of the whole woman."[28]  Cixous wants to destroy the phallogocentric system, and to empower women's bodies and language.[29] "You only have to look at the Medusa straight on to see her," writes Cixous. "And she's not deadly. She's beautiful and she's laughing."[30]
+
+Medusa has sometimes appeared as representing notions of scientific determinism and nihilism, especially in contrast with romantic idealism.[31][32] In this interpretation of Medusa, attempts to avoid looking into her eyes represent avoiding the ostensibly depressing reality that the universe is meaningless. Jack London uses Medusa in this way in his novel The Mutiny of the Elsinore:[33]
+
+I cannot help remembering a remark of De Casseres. It was over the wine in Mouquin's. Said he: "The profoundest instinct in man is to war against the truth; that is, against the Real. He shuns facts from his infancy. His life is a perpetual evasion. Miracle, chimera and to-morrow keep him alive. He lives on fiction and myth. It is the Lie that makes him free. Animals alone are given the privilege of lifting the veil of Isis; men dare not. The animal, awake, has no fictional escape from the Real because he has no imagination. Man, awake, is compelled to seek a perpetual escape into Hope, Belief, Fable, Art, God, Socialism, Immortality, Alcohol, Love. From Medusa-Truth he makes an appeal to Maya-Lie."
+
+Medusa has been depicted in several works of art, including:
+
+Medusa remained a common theme in art in the nineteenth century, when her myth was retold in Thomas Bulfinch's Mythology. Edward Burne-Jones' Perseus Cycle of paintings and a drawing by Aubrey Beardsley gave way to the twentieth century works of Paul Klee, John Singer Sargent, Pablo Picasso, Pierre et Gilles, and Auguste Rodin's bronze sculpture The Gates of Hell.[34]
+
+The most influential depiction of Medusa in film is arguably the stop motion animation created by Ray Harryhausen for Clash of the Titans (1981). As well has having snakes for hair, she was given a serpent-like body and rattlesnake-like tail. The model was one Harryhausen’s most complex and in 2020 it was voted third favourite among his many creations.
+
+The head of Medusa is featured on some regional symbols. One example is that of the flag and emblem of Sicily, together with the three legged trinacria. The inclusion of Medusa in the center implies the protection of the goddess Athena, who wore the Gorgon's likeness on her aegis, as said above. Another example is the coat of arms of Dohalice village in the Czech Republic.
+
+Municipal coat of arms of Dohalice village, Hradec Králové District, Czech Republic
+
+Flag of Sicily
+
+Ceremonial French military uniform belt of World War I
+
+Medusa is honored in the following scientific names:[35]
+
+The petrifying image of Medusa makes an instantly recognizable feature in popular culture. Medusa has been featured in several works of fiction, including video games, movies, cartoons and books. In particular, the designer Versace's symbol is reflected through the Medusa-head symbol. It was chosen because she represents beauty, art, and philosophy.[37]
+
+The motive of the Medusa has also had an appearance in some of the modern songs. One of the most notable examples is the song 'Medusa' by the American thrash metal band Anthrax, which describes this demonic creature and is the ninth track on their second studio album Spreading the Disease.

en/376.html.txt

@@ -0,0 +1,102 @@
+
+
+Cardinal Armand Jean du Plessis, Duke of Richelieu (French pronunciation: ​[aʁmɑ̃ ʒɑ̃ dy plɛsi]; 9 September 1585 – 4 December 1642), commonly referred to as Cardinal Richelieu (UK: /ˈrɪʃəljɜː, ˈriːʃ-/,[1][2][3] US: /ˈrɪʃəl(j)uː, ˈriːʃ-/;[3][4][5] French: Cardinal de Richelieu [kaʁdinal d(ə) ʁiʃ(ə)ljø] (listen)), was a French clergyman and statesman. He was consecrated as a bishop in 1607 and was appointed Foreign Secretary in 1616. Richelieu soon rose in both the Catholic Church and the French government, becoming a cardinal in 1622, and King Louis XIII's chief minister in 1624. He remained in office until his death in 1642; he was succeeded by Cardinal Mazarin, whose career he had fostered.
+
+Cardinal de Richelieu was often known by the title of the king's "Chief Minister" or "First Minister". He sought to consolidate royal power and crush domestic factions. By restraining the power of the nobility, he transformed France into a strong, centralized state. His chief foreign policy objective was to check the power of the Austro-Spanish Habsburg dynasty and to ensure French dominance in the Thirty Years' War that engulfed Europe. Although he was a cardinal, he did not hesitate to make alliances with Protestant rulers in an attempt to achieve his goals. While a powerful political figure, events like the Day of the Dupes (Jour des Dupes) show that in fact he very much depended on the king's confidence to keep this power.
+
+As alumnus of the University of Paris and headmaster of the College of Sorbonne, he renovated and extended the institution. Richelieu was also famous for his patronage of the arts; most notably, he founded the Académie française, the learned society responsible for matters pertaining to the French language. Richelieu is also known by the sobriquet l'Éminence rouge ("the Red Eminence"), from the red shade of a cardinal's clerical dress and the style "eminence" as a cardinal. As an advocate for Samuel de Champlain and of the retention of New France, he founded the Compagnie des Cent-Associés and saw the Treaty of Saint-Germain-en-Laye return Quebec City to French rule under Champlain, after the settlement had been taken by the Kirkes in 1629. The city would prove to be at the heart of Francophone culture in North America.
+
+Richelieu has been depicted in popular fiction frequently, most notably as the lead villain in Alexandre Dumas's 1844 novel The Three Musketeers and its numerous film adaptations.
+
+Born in Paris, Armand du Plessis was the fourth of five children and the last of three sons: he was delicate from childhood, and suffered frequent bouts of ill-health throughout his life. His family was somewhat prominent, belonging to the lesser nobility of Poitou:[6] his father, François du Plessis, seigneur de Richelieu, was a soldier and courtier who served as the Grand Provost of France,[7] and his mother, Susanne de La Porte, was the daughter of a famous jurist.[8] When he was five years old, his father died fighting in the French Wars of Religion,[9] leaving the family in debt; with the aid of royal grants, however, the family was able to avoid financial difficulties. At the age of nine, young Richelieu was sent to the College of Navarre in Paris to study philosophy.[10] Thereafter, he began to train for a military career.[11] His private life seems to have been typical of a young officer of the era: in 1605, aged twenty, he was treated by Théodore de Mayerne for pneumonia.[12]
+
+Henry III had rewarded Richelieu's father for his participation in the Wars of Religion by granting his family the bishopric of Luçon.[13] The family appropriated most of the revenues of the bishopric for private use; they were, however, challenged by clergymen who desired the funds for ecclesiastical purposes. To protect the important source of revenue, Richelieu's mother proposed to make her second son, Alphonse, the bishop of Luçon.[14] Alphonse, who had no desire to become a bishop, became instead a Carthusian monk.[15] Thus, it became necessary that the younger Richelieu join the clergy. He had strong academic interests and threw himself into studying for his new post.[citation needed]
+
+In 1606 Henry IV nominated Richelieu to become Bishop of Luçon.[14] As Richelieu had not yet reached the canonical minimum age, it was necessary that he journey to Rome for a special dispensation from Pope Paul V. This secured, Richelieu was consecrated bishop in April 1607. Soon after he returned to his diocese in 1608, Richelieu was heralded as a reformer.[16] He became the first bishop in France to implement the institutional reforms prescribed by the Council of Trent between 1545 and 1563.[17]
+
+At about this time, Richelieu became a friend of François Leclerc du Tremblay (better known as "Père Joseph" or "Father Joseph"), a Capuchin friar, who would later become a close confidant. Because of his closeness to Richelieu, and the grey colour of his robes, Father Joseph was also nicknamed L'éminence grise ("the Grey Eminence"). Later, Richelieu often used him as an agent during diplomatic negotiations.[18]
+
+In 1614, the clergymen of Poitou asked Richelieu to be one of their representatives to the Estates-General.[19] There, he was a vigorous advocate of the Church, arguing that it should be exempt from taxes and that bishops should have more political power. He was the most prominent clergyman to support the adoption of the decrees of the Council of Trent throughout France;[20] the Third Estate (commoners) was his chief opponent in this endeavour. At the end of the assembly, the First Estate (the clergy) chose him to deliver the address enumerating its petitions and decisions.[21] Soon after the dissolution of the Estates-General, Richelieu entered the service of King Louis XIII's wife, Anne of Austria, as her almoner.[22]
+
+Richelieu advanced politically by faithfully serving the Queen-Mother's favourite, Concino Concini, the most powerful minister in the kingdom.[23] In 1616, Richelieu was made Secretary of State, and was given responsibility for foreign affairs.[21] Like Concini, the Bishop was one of the closest advisors of Louis XIII's mother, Marie de Médicis. The Queen had become Regent of France when the nine-year-old Louis ascended the throne; although her son reached the legal age of majority in 1614, she remained the effective ruler of the realm.[24] However, her policies, and those of Concini, proved unpopular with many in France. As a result, both Marie and Concini became the targets of intrigues at court; their most powerful enemy was Charles de Luynes.[25] In April 1617, in a plot arranged by Luynes, Louis XIII ordered that Concini be arrested, and killed should he resist; Concini was consequently assassinated, and Marie de Médicis overthrown.[26] His patron having died, Richelieu also lost power; he was dismissed as Secretary of State, and was removed from the court.[26] In 1618, the King, still suspicious of the Bishop of Luçon, banished him to Avignon. There, Richelieu spent most of his time writing; he composed a catechism entitled L'Instruction du chrétien.[27]
+
+In 1619, Marie de Médicis escaped from her confinement in the Château de Blois, becoming the titular leader of an aristocratic rebellion. The King and the duc de Luynes recalled Richelieu, believing that he would be able to reason with the Queen. Richelieu was successful in this endeavour, mediating between her and her son.[28] Complex negotiations bore fruit when the Treaty of Angoulême was ratified; Marie de Médicis was given complete freedom, but would remain at peace with the King. The Queen-Mother was also restored to the royal council.[citation needed]
+
+After the death of the King's favourite, the duc de Luynes, in 1621, Richelieu rose to power quickly. The year after, the King nominated Richelieu for a cardinalate, which Pope Gregory XV accordingly granted in September 1622.[29] Crises in France, including a rebellion of the Huguenots, rendered Richelieu a nearly indispensable advisor to the King. After he was appointed to the royal council of ministers on 29 April 1624,[30] he intrigued against the chief minister, Charles, duc de La Vieuville.[28] On 12 August of the same year, La Vieuville was arrested on charges of corruption, and Cardinal Richelieu took his place as the King's principal minister the following day, although the Cardinal de la Rochefoucauld nominally remained president of the council (Richelieu was officially appointed president in November 1629).[31]
+
+Cardinal Richelieu's policy involved two primary goals: centralization of power in France[32] and opposition to the Habsburg dynasty (which ruled in both Austria and Spain).[33] Shortly after he became Louis' principal minister, he was faced with a crisis in Valtellina, a valley in Lombardy (northern Italy). To counter Spanish designs on the territory, Richelieu supported the Protestant Swiss canton of Grisons, which also claimed the strategically important valley. The Cardinal deployed troops to Valtellina, from which the Pope's garrisons were driven out.[34] Richelieu's early decision to support a Protestant canton against the Pope was a foretaste of the purely diplomatic power politics he would espouse in his foreign policy.
+
+To further consolidate power in France, Richelieu sought to suppress the influence of the feudal nobility. In 1626, he abolished the position of Constable of France and ordered all fortified castles razed, excepting only those needed to defend against invaders.[35] Thus he stripped the princes, dukes, and lesser aristocrats of important defences that could have been used against the King's armies during rebellions. As a result, Richelieu was hated by most of the nobility.
+
+Another obstacle to the centralization of power was religious division in France. The Huguenots, one of the largest political and religious factions in the country, controlled a significant military force, and were in rebellion.[36] Moreover, the King of England, Charles I, declared war on France in an attempt to aid the Huguenot faction. In 1627, Richelieu ordered the army to besiege the Huguenot stronghold of La Rochelle; the Cardinal personally commanded the besieging troops.[37] English troops under the Duke of Buckingham led an expedition to help the citizens of La Rochelle, but failed abysmally. The city, however, remained firm for over a year before capitulating in 1628.
+
+Although the Huguenots suffered a major defeat at La Rochelle, they continued to fight, led by Henri, duc de Rohan. Protestant forces, however, were defeated in 1629; Rohan submitted to the terms of the Peace of Alais.[38] As a result, religious toleration for Protestants, which had first been granted by the Edict of Nantes in 1598, was permitted to continue, but the Cardinal abolished their political rights and protections.[38] Rohan was not executed (as were leaders of rebellions later in Richelieu's tenure); in fact, he later became a commanding officer in the French army.
+
+Habsburg Spain exploited the French conflict with the Huguenots to extend its influence in northern Italy. It funded the Huguenot rebels to keep the French army occupied, meanwhile expanding its Italian dominions. Richelieu, however, responded aggressively; after La Rochelle capitulated, he personally led the French army to northern Italy to restrain Spain. On 26 November 1629, he was created duc de Richelieu and a Peer of France.
+In the next year, Richelieu's position was seriously threatened by his former patron, Marie de Médicis. Marie believed that the Cardinal had robbed her of her political influence; thus, she demanded that her son dismiss the chief minister.[39] Louis XIII was not, at first, averse to such a course of action, as he personally disliked Richelieu.[21] Despite this, the persuasive statesman was able to secure the king as an ally against his own mother. On 11 November 1630, Marie de Médicis and the King's brother, Gaston, duc d'Orléans, secured the King's agreement for the dismissal. Richelieu, however, was aware of the plan, and quickly convinced the King to repent.[40] This day, known as the Day of the Dupes, was the only one on which Louis XIII took a step toward dismissing his minister. Thereafter, the King was unwavering in his political support for him.
+
+Meanwhile, Marie de Médicis was exiled to Compiègne. Both Marie and the duc d'Orléans continued to conspire against Richelieu, but their schemes came to nothing. The nobility also remained powerless. The only important rising was that of Henri, duc de Montmorency in 1632; Richelieu, ruthless in suppressing opposition, ordered the duke's execution. In 1634, the Cardinal had one of his outspoken critics, Urbain Grandier, burned at the stake in the Loudun affair. These and other harsh measures were orchestrated by Richelieu to intimidate his enemies. He also ensured his political security by establishing a large network of spies in France as well as in other European countries.
+
+Henri Motte's depiction of Cardinal Richelieu at the Siege of La Rochelle.
+
+Letter of Cardinal Richelieu to Claude de Razilly asking him to do everything in his power to relieve Ré Island in the Siege of Saint-Martin-de-Ré, July 1627.
+
+On the "Day of the Dupes" in 1630, it appeared that Marie de Médicis had secured Richelieu's dismissal. Richelieu, however, survived the scheme, and Marie was exiled as a result.
+
+Before Richelieu's ascent to power, most of Europe had become enmeshed in the Thirty Years' War (1618–1648). France was not openly at war with the Habsburgs, who ruled Spain and the Holy Roman Empire, so subsidies and aid were provided secretly to their adversaries.[41] He considered the Dutch Republic as one of France's most important allies, for it bordered directly with the Spanish Netherlands and was right in the middle of the Eighty Years' War with Spain at that time. Luckily for him, Richelieu was a bon français, just like the king, who had already decided to subsidize the Dutch to fight against the Spanish via the Treaty of Compiègne in June 1624, prior to Richelieu's appointment to First Minister in August.[42] That same year, a military expedition, secretly financed by France and commanded by Marquis de Coeuvres, started an action with the intention of liberating the Valtelline from Spanish occupation. In 1625, Richelieu also sent money to Ernst von Mansfeld, a famous mercenary general operating in Germany in English service. However, in May 1626, when war costs had almost ruined France, king and cardinal made peace with Spain via the Treaty of Monçon.[43] This peace quickly broke down after tensions due to the War of the Mantuan Succession.[44]
+
+In 1629, Emperor Ferdinand II subjugated many of his Protestant opponents in Germany. Richelieu, alarmed by Ferdinand's growing influence, incited Sweden to intervene, providing money.[45] In the meantime, France and Spain remained hostile due to Spain's ambitions in northern Italy. At that time northern Italy was a major strategic region in Europe's balance of power, serving as a link between the Habsburgs in the Empire and in Spain. Had the imperial armies dominated this region, France would have been threatened by Habsburg encirclement. Spain was meanwhile seeking papal approval for a universal monarchy. When in 1630 French diplomats in Regensburg agreed to make peace with Spain, Richelieu refused to support them. The agreement would have prohibited French interference in Germany. Therefore, Richelieu advised Louis XIII to refuse to ratify the treaty. In 1631, he allied France to Sweden, who had just invaded the empire, in the Treaty of Bärwalde.[45]
+
+Military expenses placed a considerable strain on royal revenues. In response, Richelieu raised the gabelle (salt tax) and the taille (land tax).[46] The taille was enforced to provide funds to raise armies and wage war. The clergy, nobility, and high bourgeoisie were either exempt or could easily avoid payment, so the burden fell on the poorest segment of the nation. To collect taxes more efficiently, and to keep corruption to a minimum, Richelieu bypassed local tax officials, replacing them with intendants (officials in the direct service of the Crown).[47] Richelieu's financial scheme, however, caused unrest among the peasants; there were several uprisings in 1636 to 1639.[48] Richelieu crushed the revolts violently, and dealt with the rebels harshly.[49]
+
+Because he openly aligned France with Protestant powers, Richelieu was denounced by many as a traitor to the Roman Catholic Church. Military action, at first, was disastrous for the French, with many victories going to Spain and the Empire.[50] Neither side, however, could obtain a decisive advantage, and the conflict lingered on after Richelieu's death. Richelieu was instrumental in redirecting the Thirty Years' War from the conflict of Protestantism versus Catholicism to that of nationalism versus Habsburg hegemony.[51] In this conflict France effectively drained the already overstretched resources of the Habsburg empire and drove it inexorably towards bankruptcy.[52] The defeat of Habsburg forces at the Battle of Lens in 1648, coupled with their failure to prevent a French invasion of Catalonia, effectively spelled the end for Habsburg domination of the continent, and for the personal career of Spanish prime minister Olivares.[52] Indeed, in the subsequent years it would be France, under the leadership of Louis XIV, who would attempt to fill the vacuum left by the Habsburgs in the Spanish Netherlands and supplant Spain as the dominant European power.[citation needed]
+
+When Richelieu came to power, New France, where the French had a foothold since Jacques Cartier, had no more than 100 permanent European inhabitants.[53] Richelieu encouraged Louis XIII to colonize the Americas by the foundation of the Compagnie de la Nouvelle France in imitation of the Dutch West India Company. Unlike the other colonial powers, France encouraged a peaceful coexistence in New France between Natives and Colonists and sought the integration of Indians into colonial society.[54][55] Samuel de Champlain, governor of New France at the time of Richelieu, saw intermarriage between French and Indians as a solution to increase population in its colony.[56] Under the guidance of Richelieu, Louis XIII issued the Ordonnance of 1627 by which the Indians, converted to Catholicism, were considered as "natural Frenchmen":
+
+The descendants of the French who are accustomed to this country [New France], together with all the Indians who will be brought to the knowledge of the faith and will profess it, shall be deemed and renowned natural Frenchmen, and as such may come to live in France when they want, and acquire, donate, and succeed and accept donations and legacies, just as true French subjects, without being required to take letters of declaration of naturalization.[57]
+
+The 1666 census of New France, conducted some 20 years after the death of Cardinal Richelieu, showed a population of 3,215 habitants in New France, many more than there had been only a few decades earlier, but also a great difference in the number of men (2,034) and women (1,181).[58]
+
+Towards the end of his life, Richelieu alienated many people, including Pope Urban VIII. Richelieu was displeased by the Pope's refusal to name him the papal legate in France;[59] in turn, the Pope did not approve of the administration of the French church, or of French foreign policy. However, the conflict was largely healed when the Pope granted a cardinalate to Jules Mazarin, one of Richelieu's foremost political allies, in 1641. Despite troubled relations with the Roman Catholic Church, Richelieu did not support the complete repudiation of papal authority in France, as was advocated by the Gallicanists.[60]
+
+As he neared death, Richelieu faced a plot that threatened to remove him from power. The cardinal had introduced a young man named Henri Coiffier de Ruzé, marquis de Cinq-Mars to Louis XIII's court.[61] The Cardinal had been a friend of Cinq-Mars' father.[61] More importantly, Richelieu hoped that Cinq-Mars would become Louis' favourite, so that he could indirectly exercise greater influence over the monarch's decisions. Cinq-Mars had become the royal favourite by 1639, but, contrary to Cardinal Richelieu's belief, he was not easy to control. The young marquis realized that Richelieu would not permit him to gain political power.[62] In 1641, he participated in the comte de Soissons' failed conspiracy against Richelieu, but was not discovered.[63] Then, the following year, he schemed with leading nobles (including the King's brother, the duc d'Orléans) to raise a rebellion; he also signed a secret agreement with the King of Spain, who promised to aid the rebels.[64] Richelieu's spy service, however, discovered the plot, and the Cardinal received a copy of the treaty.[65] Cinq-Mars was promptly arrested and executed; although Louis approved the use of capital punishment, he grew more distant from Richelieu as a result.[citation needed]
+
+However, Richelieu was now dying. For many years he had suffered from recurrent fevers (possibly malaria), strangury, intestinal tuberculosis with fistula, and migraine. Now his right arm was suppurating with tubercular osteitis, and he coughed blood (after his death, his lungs were found to have extensive cavities and caseous necrosis). His doctors continued to bleed him frequently, further weakening him.[66] As he felt his death approaching, he named Mazarin, one of his most faithful followers, to succeed him as chief minister to the King.[67]
+
+Richelieu died on 4 December 1642, aged 57. His body was embalmed and interred at the church of the Sorbonne. During the French Revolution, the corpse was removed from its tomb, and the mummified front of his head, having been removed and replaced during the original embalming process, was stolen. It ended up in the possession of Nicholas Armez of Brittany by 1796, and he occasionally exhibited the well-preserved face. His nephew, Louis-Philippe Armez, inherited it and also occasionally exhibited it and lent it out for study. In 1866, Napoleon III persuaded Armez to return the face to the government for re-interment with the rest of Richelieu's body. An investigation of subsidence of the church floor enabled the head to be photographed in 1895.[68][69]
+
+Richelieu was a famous patron of the arts. An author of various religious and political works (most notably his Political Testament), he sent his agents abroad[70] in search of books and manuscripts for his unrivaled library, which he specified in his will – leaving it to his great-nephew fully funded – should serve not merely his family but to be open at fixed hours to scholars. The manuscripts alone numbered some 900, bound as codices in red Morocco with the cardinal's arms. The library was transferred to the Sorbonne in 1660.[71] He funded the literary careers of many writers. He was a lover of the theatre, which was not considered a respectable art form during that era; a private theatre was a feature of the Palais-Cardinal. Among the individuals he patronized was the famous playwright Pierre Corneille.[72] Richelieu was also the founder and patron of the Académie française, the pre-eminent French literary society.[73] The institution had previously been in informal existence; in 1635, however, Cardinal Richelieu obtained official letters patent for the body. The Académie française includes forty members, promotes French literature, and remains the official authority on the French language. Richelieu served as the Académie's protector. Since 1672, that role has been fulfilled by the French head of state.[citation needed]
+
+In 1622, Richelieu was elected the proviseur or principal of the Sorbonne.[74] He presided over the renovation of the college's buildings and over the construction of its famous chapel, where he is now entombed. As he was Bishop of Luçon, his statue stands outside the Luçon cathedral.[citation needed]
+
+Richelieu oversaw the construction of his own palace in Paris, the Palais-Cardinal.[75] The palace, renamed the Palais Royal after Richelieu's death, now houses the French Constitutional Council, the Ministry of Culture, and the Conseil d'État. The Galerie de l'avant-cour had ceiling paintings by the Cardinal's chief portraitist, Philippe de Champaigne, celebrating the major events of the Cardinal's career; the Galerie des hommes illustres had twenty-six historicizing portraits of great men, larger than life, from Abbot Suger to Louis XIII; some were by Simon Vouet, others were careful copies by Philippe de Champaigne from known portraits;[76] with them were busts of Roman emperors. Another series of portraits of authors complemented the library.  The architect of the Palais-Cardinal, Jacques Lemercier, also received a commission to build a château and a surrounding town in Indre-et-Loire; the project culminated in the construction of the Château Richelieu and the town of Richelieu. To the château, he added one of the largest art collections in Europe and the largest collection of ancient Roman sculpture in France. The heavily resurfaced and restored Richelieu Bacchus continued to be admired by neoclassical artists.[77] Among his 300 paintings by moderns, most notably, he owned Leonardo's Virgin and Child with Saint Anne, The Family of the Virgin by Andrea del Sarto, the two famous Bacchanales of Nicolas Poussin, as well as paintings by Veronese and Titian, and Diana at the Bath by Rubens, for which he was so glad to pay the artist's heirs 3,000 écus, that he made a gift to Rubens' widow of a diamond-encrusted watch. His marble portrait bust by Bernini was not considered a good likeness and was banished to a passageway.[78]
+
+The fittings of his chapel in the Palais-Cardinal, for which Simon Vouet executed the paintings, were of solid gold – crucifix, chalice, paten, ciborium, candlesticks – set with 180 rubies and 9,000 diamonds.[79] His taste also ran to massive silver, small bronzes and works of vertu, enamels and rock crystal mounted in gold, Chinese porcelains, tapestries and Persian carpets, cabinets from Italy, and Antwerp and the heart-shaped diamond bought from Alphonse Lopez that he willed to the king.  When the Palais-Cardinal was complete, he donated it to the Crown, in 1636. With the Queen in residence, the paintings of the Grand Cabinet were transferred to Fontainebleau and replaced by copies, and the interiors were subjected to much rearrangement.[citation needed]
+
+Michelangelo's two Slaves were among the rich appointments of the château Richelieu, where there were the Nativity triptych by Dürer, and paintings by Mantegna, Lorenzo Costa and Perugino, lifted from the Gonzaga collection at Mantua by French military forces in 1630, as well as numerous antiquities.[citation needed]
+
+Richelieu's tenure was a crucial period of reform for France. Earlier, the nation's political structure was largely feudal, with powerful nobles and a wide variety of laws in different regions.[81] Parts of the nobility periodically conspired against the King, raised private armies, and allied themselves with foreign powers. This system gave way to centralized power under Richelieu.[82] Local and even religious interests were subordinated to those of the whole nation, and of the embodiment of the nation – the King. Equally critical for France was Richelieu's foreign policy, which helped restrain Habsburg influence in Europe. Richelieu did not survive to the end of the Thirty Years' War. However, the conflict ended in 1648, with France emerging in a far better position than any other power, and the Holy Roman Empire entering a period of decline.[citation needed]
+
+Richelieu's successes were extremely important to Louis XIII's successor, King Louis XIV. He continued Richelieu's work of creating an absolute monarchy; in the same vein as the Cardinal, he enacted policies that further suppressed the once-mighty aristocracy, and utterly destroyed all remnants of Huguenot political power with the Edict of Fontainebleau. Moreover, Louis took advantage of his nation's success during the Thirty Years' War to establish French hegemony in continental Europe. Thus, Richelieu's policies were the requisite prelude to Louis XIV becoming the most powerful monarch, and France the most powerful nation, in all of Europe during the late seventeenth century.[citation needed]
+
+Richelieu is also notable for the authoritarian measures he employed to maintain power. He censored the press,[83] established a large network of internal spies, forbade the discussion of political matters in public assemblies such as the Parlement de Paris (a court of justice), and had those who dared to conspire against him prosecuted and executed. The Canadian historian and philosopher John Ralston Saul has referred to Richelieu as the "father of the modern nation-state, modern centralised power [and] the modern secret service."[citation needed]
+
+Richelieu's motives are the focus of much debate among historians: some see him as a patriotic supporter of the monarchy, while others view him as a power-hungry cynic. The latter image gained further currency due to Alexandre Dumas' The Three Musketeers, which depicts Richelieu as a self-serving and ruthless de facto ruler of France.[citation needed]
+
+Despite such arguments, Richelieu remains an honoured personality in France. He has given his name to a battleship and a battleship class.
+
+His legacy is also important for the world at large; his ideas of a strong nation-state and aggressive foreign policy helped create the modern system of international politics. The notions of national sovereignty and international law can be traced, at least in part, to Richelieu's policies and theories, especially as enunciated in the Treaty of Westphalia that ended the Thirty Years' War.[citation needed]
+
+A less renowned aspect of his legacy is his involvement with Samuel de Champlain and the fledgling colony along the St. Lawrence River. The retention and promotion of Canada under Richelieu allowed it – and through the settlement's strategic location, the St. Lawrence-Great Lakes gateway into the North American interior – to develop into a French empire in North America, parts of which eventually became modern Canada and Louisiana.[citation needed]
+
+As of April 2013, the Internet Movie Database listed 94 films and television programs in which Cardinal Richelieu is a character. Richelieu is one of the clergymen most frequently portrayed in film, notably in the many versions of Alexandre Dumas's The Three Musketeers. He is usually portrayed as a sinister character, but the 1950 Cyrano de Bergerac shows Richelieu (played by Edgar Barrier in a scene not from Rostand's original verse drama) as compassionate to Cyrano's financial plight, and playfully having enjoyed the duel at the theatre. Actors who have portrayed Cardinal Richelieu on film and television include Nigel De Brulier, George Arliss, Miles Mander, Vincent Price, Charlton Heston, Tcheky Karyo, Stephen Rea, Tim Curry, Christoph Waltz and Peter Capaldi.
+
+The 1839 play Richelieu; Or the Conspiracy, by Edward Bulwer-Lytton, portrayed Richelieu uttering the now famous line, "The pen is mightier than the sword." The play was adapted into the 1935 film Cardinal Richelieu.[citation needed]
+
+In the 1969 episode "How to Recognise Different Types of Trees from Quite a Long Way Away" from Monty Python's Flying Circus there is the sketch "Court Scene with Cardinal Richelieu" in which Michael Palin in Richelieu's likeness is seen to be doing wildly absurd acts.[84]
+
+In the 1632/Ring of Fire series by Eric Flint, he is one of the primary antagonists to the nascent United States of Europe.
+
+Many sites and landmarks were named to honor Cardinal Richelieu. They include:[85]
+
+There is also an ornate style of lace, Richelieu lace, named in honor of the cardinal.[86]

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+Megalodon (Carcharocles megalodon), meaning "big tooth", is an extinct species of shark that lived approximately 23 to 3.6 million years ago (mya), during the Early Miocene to the Pliocene.[6] It was formerly thought to be a member of the family Lamnidae and a close relative of the great white shark (Carcharodon carcharias). However, it is now classified into the extinct family Otodontidae, which diverged from the great white shark during the Early Cretaceous. Its genus placement is still debated, authors placing it in either Carcharocles, Megaselachus, Otodus, or Procarcharodon. This is because transitional fossils have been found showing that Megalodon is the final chronospecies of a lineage of giant sharks originally of the genus Otodus which evolved during the Paleocene.
+
+While regarded as one of the largest and most powerful predators to have ever lived, megalodon is known from fragmentary remains, and its appearance and maximum size are uncertain. Scientists differ on whether it would have more closely resembled a stockier version of the great white shark, the basking shark (Cetorhinus maximus) or the sand tiger shark (Carcharias taurus). Most estimates of megalodon's size extrapolate from teeth; with maximum length estimates up to 18 meters (59 ft) and average length estimates of 10.5 meters (34 ft). Estimates suggest their large jaws could exert a bite force of up to 110,000 to 180,000 newtons (25,000 to 40,000 lbf).[7] Their teeth were thick and robust, built for grabbing prey and breaking bone.
+
+Megalodon probably had a major impact on the structure of marine communities. The fossil record indicates that it had a cosmopolitan distribution. It probably targeted large prey, such as whales, seals and sea turtles. Juveniles inhabited warm coastal waters and fed on fish and small whales. Unlike the great white, which attacks prey from the soft underside, megalodon probably used its strong jaws to break through the chest cavity and puncture the heart and lungs of its prey.
+
+The animal faced competition from whale-eating cetaceans, such as Livyatan and other macroraptorial sperm whales and possibly smaller ancestral killer whales. As the shark preferred warmer waters, it is thought that oceanic cooling associated with the onset of the ice ages, coupled with the lowering of sea levels and resulting loss of suitable nursery areas, may have also contributed to its decline. A reduction in the diversity of baleen whales and a shift in their distribution toward polar regions may have reduced megalodon's primary food source. A 2019 study reviewed newer evidence suggesting that competition from the modern great white shark may have also contributed to the extinction of megalodon, coupled with range fragmentation resulting in a gradual, asynchronous extinction as a result of cooling oceans around 3.6–4 million years ago, far earlier than previously assumed.[8] The extinction of the shark appeared to affect other animals; for example, the size of baleen whales increased significantly after the shark had disappeared.
+
+According to Renaissance accounts, gigantic triangular fossil teeth often found embedded in rocky formations were once believed to be the petrified tongues, or glossopetrae, of dragons and snakes. This interpretation was corrected in 1667 by Danish naturalist Nicolas Steno, who recognized them as shark teeth, and famously produced a depiction of a shark's head bearing such teeth. He described his findings in the book The Head of a Shark Dissected, which also contained an illustration of a megalodon tooth.[9][10][11]
+
+Swiss naturalist Louis Agassiz gave this shark its initial scientific name, Carcharodon megalodon, in his 1843 work Recherches sur les poissons fossiles, based on tooth remains.[1][12] English paleontologist Edward Charlesworth in his 1837 paper used the name Carcharias megalodon, while citing Agassiz as the author, indicating that Agassiz described the species prior to 1843. English paleontologist Charles Davies Sherborn in 1928 listed an 1835 series of articles by Agassiz as the first scientific description of the shark.[13] The specific name megalodon translates to "big tooth", from Ancient Greek: μέγας, romanized: (mégas), lit. 'big, mighty' and ὀδούς (odoús), "tooth".[14][15] The teeth of megalodon are morphologically similar to those of the great white shark (Carcharodon carcharias), and on the basis of this observation, Agassiz assigned megalodon to the genus Carcharodon.[12] Though “megalodon” is an informal name for the shark, it is also often informally dubbed the "giant white shark",[16] the "megatooth shark", the "big tooth shark", or "Meg".[17]:4
+
+There was one apparent description of the shark in 1881 classifying it as Selache manzonii.[18]
+
+Otodus obliquus
+
+Carcharocles megalodon
+
+Isurus hastalis
+
+Carcharodon carcharias
+
+While the earliest megalodon remains have been reported from the Late Oligocene, around 28 million years ago (mya),[20][21] there is disagreement as to when it appeared, with dates ranging to as young as 16 mya.[22] It has been thought that megalodon became extinct around the end of the Pliocene, about 2.6 mya;[22][23] claims of Pleistocene megalodon teeth, younger than 2.6 million years old, are considered unreliable.[23] A more recent assessment moves the extinction date back to earlier in the Pliocene, 3.6 mya.[8]
+
+Megalodon is now considered to be a member of the family Otodontidae, genus Carcharocles, as opposed to its previous classification into Lamnidae, genus Carcharodon.[22][23][24][25] Megalodon's classification into Carcharodon was due to dental similarity with the great white shark, but most authors currently believe that this is due to convergent evolution. In this model, the great white shark is more closely related to the extinct broad-toothed mako (Isurus hastalis) than to megalodon, as evidenced by more similar dentition in those two sharks; megalodon teeth have much finer serrations than great white shark teeth. The great white shark is more closely related to the mako shark (Isurus spp.), with a common ancestor around 4 mya.[12][19] Proponents of the former model, wherein megalodon and the great white shark are more closely related, argue that the differences between their dentition are minute and obscure.[26]:23–25
+
+The genus Carcharocles currently contains four species: C. auriculatus, C. angustidens, C. chubutensis, and C. megalodon.[17]:30–31  The evolution of this lineage is characterized by the increase of serrations, the widening of the crown, the development of a more triangular shape, and the disappearance of the lateral cusps.[17]:28–31[27] The evolution in tooth morphology reflects a shift in predation tactics from a tearing-grasping bite to a cutting bite, likely reflecting a shift in prey choice from fish to cetaceans.[28] Lateral cusplets were finally lost in a gradual process that took roughly 12 million years during the transition between C. chubutensis and C. megalodon.[28] The genus was proposed by D. S. Jordan and H. Hannibal in 1923 to contain C. auriculatus. In the 1980s, megalodon was assigned to Carcharocles.[12][17]:30 Before this, in 1960, the genus Procarcharodon was erected by French ichthyologist Edgard Casier, which included those four sharks and was considered separate from the great white shark. It is now considered a junior synonym of Carcharocles.[17]:30 The genus Palaeocarcharodon was erected alongside Procarcharodon to represent the beginning of the lineage, and, in the model wherein megalodon and the great white shark are closely related, their last common ancestor. It is believed to be an evolutionary dead-end and unrelated to the Carcharocles sharks by authors who reject that model.[26]:70
+
+Another model of the evolution of this genus, also proposed by Casier in 1960, is that the direct ancestor of the Carcharocles is the shark Otodus obliquus, which lived from the Paleocene through the Miocene epochs, 60 mya to 13 mya.[19][27] The genus Otodus is ultimately derived from Cretolamna, a shark from the Cretaceous period.[24][29] In this model, O. obliquus evolved into O. aksuaticus, which evolved into C. auriculatus, and then into C. angustidens, and then into C. chubutensis, and then finally into C. megalodon.
+
+Another model of the evolution of Carcharocles, proposed in 2001 by paleontologist Michael Benton, is that the three other species are actually a single species of shark that gradually changed over time between the Paleocene and the Pliocene, making it a chronospecies.[17]:17[21][30] Some authors suggest that C. auriculatus, C. angustidens, and C. chubutensis should be classified as a single species in the genus Otodus, leaving C. megalodon the sole member of Carcharocles.[21][31]
+
+The genus Carcharocles may be invalid, and the shark may actually belong in the genus Otodus, making it Otodus megalodon.[4] A 1974 study on Paleogene sharks by Henri Cappetta erected the subgenus Megaselachus, classifying the shark as Otodus (Megaselachus) megalodon, along with O. (M.) chubutensis. A 2006 review of Chondrichthyes elevated Megaselachus to genus, and classified the sharks as Megaselachus megalodon and M. chubutensis.[4] The discovery of fossils assigned to the genus Megalolamna in 2016 led to a re-evaluation of Otodus, which concluded that it is paraphyletic, that is, it consists of a last common ancestor but it does not include all of its descendants. The inclusion of the Carcharocles sharks in Otodus would make it monophyletic, with the sister clade being Megalolamna.[24]
+
+One interpretation on how megalodon appeared was that it was a robust-looking shark, and may have had a similar build to the great white shark. The jaws may have been blunter and wider than the great white, and the fins would have also been similar in shape, though thicker due to its size. It may have had a pig-eyed appearance, in that it had small, deep-set eyes.[26]:64–65
+
+Another interpretation is that megalodon bore a similarity to the whale shark (Rhincodon typus) or the basking shark (Cetorhinus maximus). The tail fin would have been crescent-shaped, the anal fin and second dorsal fin would have been small, and there would have been a caudal keel present on either side of the tail fin (on the caudal peduncle). This build is common in other large aquatic animals, such as whales, tuna, and other sharks, in order to reduce drag while swimming. The head shape can vary between species as most of the drag-reducing adaptations are toward the tail-end of the animal.[17]:35–36
+
+Since Carcharocles is derived from Otodus, and the two had teeth that bear a close similarity to those of the sand tiger shark (Carcharias taurus), megalodon may have had a build more similar to the sand tiger shark than to other sharks. This is unlikely since the sand tiger shark is a carangiform swimmer which requires faster movement of the tail for propulsion through the water than the great white shark, a thunniform swimmer.[17]:35–36[32]
+
+Due to fragmentary remains, there have been many contradictory size estimates for megalodon, as they can only be drawn from fossil teeth and vertebrae.[17]:87[33] Also because of this, the great white shark is the basis of its reconstruction and size estimation,[26]:57 as it is regarded as the best analogue to megalodon.[31] Using length estimates extrapolated from 544 teeth found throughout geological time and geography, including adults and juveniles, a 2015 study estimated an average length of 10.5 meters (34 ft).[22][25] In comparison, the maximum recorded size of the great white shark is 6.1 meters (20 ft), and the whale shark (the largest living fish) can reach 18.8 m (62 ft).[34][35][36][37] It is possible that different populations of megalodon around the globe had different body sizes and behaviors due to different ecological pressures.[25] In any event, it is thought to have been the largest macropredatory shark that ever lived.[38]
+
+Mature male megalodon may have had a body mass of 12.6 to 33.9 metric tons (13.9 to 37.4 short tons), and mature females may have been 27.4 to 59.4 metric tons (30.2 to 65.5 short tons), assuming that males could range in length from 10.5 to 14.3 meters (34 to 47 ft) and females 13.3 to 17 meters (44 to 56 ft).[26]:61[7] A 2015 study linking shark size and typical swimming speed estimated that megalodon would have typically swum at 18 kilometers per hour (11 mph)–assuming that its body mass was typically 48 metric tons (53 short tons)–which is consistent with other aquatic creatures of its size, such as the fin whale (Balaenoptera physalus) which typically cruises at speeds of 14.5 to 21.5 km/h (9.0 to 13.4 mph).[39]
+
+Its large size may have been due to climatic factors and the abundance of large prey items, and it may have also been influenced by the evolution of regional endothermy (mesothermy) which would have increased its metabolic rate and swimming speed. The otodontid sharks have been considered to have been ectotherms, so on that basis megalodon would have been ectothermic. However, the largest contemporary ectothermic sharks, such as the whale shark, are filter feeders, while lamnids are now known to be regional endotherms, implying some metabolic correlations with a predatory lifestyle. These considerations, as well as tooth oxygen isotopic data and the need for higher burst swimming speeds in macropredators of endothermic prey than ectothermy would allow, imply that otodontids, including megalodon, were probably regional endotherms.[40]
+
+Gordon Hubbell from Gainesville, Florida, possesses an upper anterior megalodon tooth whose maximum height is 18.4 centimeters (7.25 in), one of the largest known tooth specimens from the shark.[41] In addition, a 2.7-by-3.4-meter (9 by 11 ft) megalodon jaw reconstruction developed by fossil hunter Vito Bertucci contains a tooth whose maximum height is reportedly over 18 centimeters (7 in).[42]
+
+The first attempt to reconstruct the jaw of megalodon was made by Bashford Dean in 1909, displayed at the American Museum of Natural History. From the dimensions of this jaw reconstruction, it was hypothesized that megalodon could have approached 30 meters (98 ft) in length. Dean had overestimated the size of the cartilage on both jaws, causing it to be too tall.[43][44]
+
+In 1973, John E. Randall, an ichthyologist, used the enamel height (the vertical distance of the blade from the base of the enamel portion of the tooth to its tip) to measure the length of the shark, yielding a maximum length of about 13 meters (43 ft).[45] However, tooth enamel height does not necessarily increase in proportion to the animal's total length.[26]:99
+
+In 1994, marine biologists Patrick J. Schembri and Stephen Papson opined that C. megalodon may have approached a maximum of around 24 to 25 meters (79 to 82 ft) in total length.[46][47]
+
+In 1996, shark researchers Michael D. Gottfried, Leonard Compagno, and S. Curtis Bowman proposed a linear relationship between a shark's total length and the height of the largest upper anterior tooth. The proposed relationship is: total length in meters = − (0.096) × [UA maximum height (mm)]-(0.22).[21][26]:60 They asserted that C. megalodon could have reached a maximum of 20.3 meters (67 ft) in total length.[7][26][48]
+
+In 2002, shark researcher Clifford Jeremiah proposed that total length was proportional to the root width of an upper anterior tooth. He claimed that for every 1 centimeter (0.39 in) of root width, there are approximately 1.4 meters (4.6 ft) of shark length. Jeremiah pointed out that the jaw perimeter of a shark is directly proportional to its total length, with the width of the roots of the largest teeth being a tool for estimating jaw perimeter. The largest tooth in Jeremiah's possession had a root width of about 12 centimeters (4.7 in), which yielded 16.5 meters (54 ft) in total length.[17]:88
+
+In 2002, paleontologist Kenshu Shimada of DePaul University proposed a linear relationship between tooth crown height and total length after conducting anatomical analysis of several specimens, allowing any sized tooth to be used. Shimada stated that the previously proposed methods were based on a less-reliable evaluation of the dental homology between megalodon and the great white shark, and that the growth rate between the crown and root is not isometric, which he considered in his model. Using this model, the upper anterior tooth possessed by Gottfried and colleagues corresponded to a total length of 15 meters (49 ft).[49] Among several specimens found in the Gatún Formation of Panama, one upper lateral tooth was used by other researchers to obtain a total length estimate of 17.9 meters (59 ft) using this method.[31][50]
+
+In 2019, Shimada revisited the size of megalodon and discouraged using non-anterior teeth for estimations, noting that the exact position of isolated non-anterior teeth is difficult to identify. Shimada stated that the maximum total length estimates, based on upper anterior teeth that are available in museums, are 14.2 and 15.3 meters (47 and 50 ft), depending on the estimation method used.[51]
+
+The most common fossils of megalodon are its teeth. Diagnostic characteristics include a triangular shape, robust structure, large size, fine serrations, a lack of lateral denticles, and a visible V-shaped neck (where the root meets the crown).[26]:55[31] The tooth met the jaw at a steep angle, similar to the great white shark. The tooth was anchored by connective tissue fibers, and the roughness of the base may have added to mechanical strength.[52] The lingual side of the tooth, the part facing the tongue, was convex; and the labial side, the other side of the tooth, was slightly convex or flat. The anterior teeth were almost perpendicular to the jaw and symmetrical, whereas the posterior teeth were slanted and asymmetrical.[53]
+
+Megalodon teeth can measure over 180 millimeters (7.1 in) in slant height (diagonal length) and are the largest of any known shark species,[17]:33 implying it was the largest of all macropredatory sharks.[38] In 1989, a nearly complete set of megalodon teeth was discovered in Saitama, Japan. Another nearly complete associated megalodon dentition was excavated from the Yorktown Formations in the United States, and served as the basis of a jaw reconstruction of megalodon at the National Museum of Natural History (USNM). Based on these discoveries, an artificial dental formula was put together for megalodon in 1996.[26]:55[54]
+
+The dental formula of megalodon is: 2.1.7.43.0.8.4. As evident from the formula, megalodon had four kinds of teeth in its jaws: anterior, intermediate, lateral, and posterior. Megalodon's intermediate tooth technically appears to be an upper anterior and is termed as "A3" because it is fairly symmetrical and does not point mesially (side of the tooth toward the midline of the jaws where the left and right jaws meet). Megalodon had a very robust dentition,[26]:20–21 and had over 250 teeth in its jaws, spanning 5 rows.[17]:iv It is possible that large megalodon individuals had jaws spanning roughly 2 meters (6.6 ft) across.[17]:129 The teeth were also serrated, which would have improved efficiency in cutting through flesh or bone.[12][17]:1 The shark may have been able to open its mouth to a 75° angle, though a reconstruction at the USNM approximates a 100° angle.[26]:63
+
+In 2008, a team of scientists led by S. Wroe conducted an experiment to determine the bite force of the great white shark, using a 2.5-meter (8.2 ft) long specimen, and then isometrically scaled the results for its maximum size and the conservative minimum and maximum body mass of megalodon. They placed the bite force of the latter between 108,514 to 182,201 newtons (24,395 to 40,960 lbf) in a posterior bite, compared to the 18,216 newtons (4,095 lbf) bite force for the largest confirmed great white shark, and 7,400 newtons (1,700 lbf) for the placoderm fish Dunkleosteus. In addition, Wroe and colleagues pointed out that sharks shake sideways while feeding, amplifying the force generated, which would probably have caused the total force experienced by prey to be higher than the estimate.[7][55]
+
+Megalodon is represented in the fossil record by teeth, vertebral centra, and coprolites.[26]:57 As with all sharks, the skeleton of megalodon was formed of cartilage rather than bone; consequently most fossil specimens are poorly preserved.[56] To support its large dentition, the jaws of megalodon would have been more massive, stouter, and more strongly developed than those of the great white, which possesses a comparatively gracile dentition. Its chondrocranium, the cartilaginous skull, would have had a blockier and more robust appearance than that of the great white. Its fins were proportional to its larger size.[26]:64–65
+
+Some fossil vertebrae have been found. The most notable example is a partially preserved vertebral column of a single specimen, excavated in the Antwerp Basin, Belgium, in 1926. It comprises 150 vertebral centra, with the centra ranging from 55 millimeters (2.2 in) to 155 millimeters (6 in) in diameter. The shark's vertebrae may have gotten much bigger, and scrutiny of the specimen revealed that it had a higher vertebral count than specimens of any known shark, possibly over 200 centra; only the great white approached it.[26]:63–65 Another partially preserved vertebral column of a megalodon was excavated from the Gram Formation in Denmark in 1983, which comprises 20 vertebral centra, with the centra ranging from 100 millimeters (4 in) to 230 millimeters (9 in) in diameter.[52]
+
+The coprolite remains of megalodon are spiral-shaped, indicating that the shark may have had a spiral valve, a corkscrew-shaped portion of the lower intestines, similar to extant lamniform sharks. Miocene coprolite remains were discovered in Beaufort County, South Carolina, with one measuring 14 cm (5.5 in).[57]
+
+Gottfried and colleagues reconstructed the entire skeleton of megalodon, which was later put on display at the Calvert Marine Museum in the United States and the Iziko South African Museum.[26]:56[27] This reconstruction is 11.3 meters (37 ft) long and represents a mature male,[26]:61 based on the ontogenetic changes a great white shark experiences over the course of its life.[26]:65
+
+Megalodon had a cosmopolitan distribution;[22][50] its fossils have been excavated from many parts of the world, including Europe, Africa, the Americas, and Australia.[26]:67[58] It most commonly occurred in subtropical to temperate latitudes.[22][26]:78 It has been found at latitudes up to 55° N; its inferred tolerated temperature range was 1–24 °C (34–75 °F).[note 1] It arguably had the capacity to endure such low temperatures due to mesothermy, the physiological capability of large sharks to conserve metabolic heat by maintaining a higher body temperature than the surrounding water.[22]
+
+Megalodon inhabited a wide range of marine environments (i.e., shallow coastal waters, areas of coastal upwelling, swampy coastal lagoons, sandy littorals, and offshore deep water environments), and exhibited a transient lifestyle. Adult megalodon were not abundant in shallow water environments, and mostly inhabited offshore areas. Megalodon may have moved between coastal and oceanic waters, particularly in different stages of its life cycle.[17]:33[60]
+
+Fossil remains show a trend for specimens to be larger on average in the southern hemisphere than in the northern, with mean lengths of 11.6 and 9.6 meters (38 and 31 ft), respectively; and also larger in the Pacific than the Atlantic, with mean lengths of 10.9 and 9.5 meters (36 and 31 ft) respectively. They do not suggest any trend of changing body size with absolute latitude, or of change in size over time (although the Carcharocles lineage in general is thought to display a trend of increasing size over time). The overall modal length has been estimated at 10.5 meters (34 ft), with the length distribution skewed towards larger individuals, suggesting an ecological or competitive advantage for larger body size.[25]
+
+Megalodon had a global distribution and fossils of the shark have been found in many places around the world, bordering all oceans of the Neogene.[61]
+
+Though sharks are generally opportunistic feeders, megalodon's great size, high-speed swimming capability, and powerful jaws, coupled with an impressive feeding apparatus, made it an apex predator capable of consuming a broad spectrum of animals. It was probably one of the most powerful predators to have existed.[26]:71–75[7] A study focusing on calcium isotopes of extinct and extant elasmobranch sharks and rays revealed that megalodon fed at a higher trophic level than the contemporaneous great white shark. That is to say it was higher up in the food chain.[62]
+
+Fossil evidence indicates that megalodon preyed upon many cetacean species, such as dolphins, small whales, cetotheres, squalodontids (shark toothed dolphins), sperm whales, bowhead whales, and rorquals.[43][63][64] In addition to this, they also targeted seals, sirenians, and sea turtles.[60] The shark was an opportunist and piscivorous, and it would have also gone after smaller fish and other sharks.[43] Many whale bones have been found with deep gashes most likely made by their teeth.[26]:75 Various excavations have revealed megalodon teeth lying close to the chewed remains of whales,[26]:75[27] and sometimes in direct association with them.[16]
+
+The feeding ecology of megalodon appears to have varied with age and between sites, like the modern great white. It is plausible that the adult megalodon population off the coast of Peru targeted primarily cetothere whales 2.5 to 7 meters (8.2 to 23 ft) in length and other prey smaller than itself, rather than large whales in the same size class as themselves.[63] Meanwhile, juveniles likely had a diet that consisted more of fish.[31][65]
+
+Megalodon faced a highly competitive environment.[66] Its position at the top of the food chain,[67] probably had a significant impact on the structuring of marine communities.[66][68] Fossil evidence indicates a correlation between megalodon and the emergence and diversification of cetaceans and other marine mammals.[26]:78[66] Juvenile megalodon preferred habitats where small cetaceans were abundant, and adult megalodon preferred habitats where large cetaceans were abundant. Such preferences may have developed shortly after they appeared in the Oligocene.[26]:74–75
+
+Megalodon were contemporaneous with whale-eating toothed whales (particularly macroraptorial sperm whales and squalodontids), which were also probably among the era's apex predators, and provided competition.[66] Some attained gigantic sizes, such as Livyatan, which grew from 13.5 to 17.5 meters (44 to 57 ft). Fossilized teeth of an undetermined species of such physeteroids from Lee Creek Mine, North Carolina, indicate it had a maximum body length of 8–10 m and a maximum lifespan of about 25 years. This is very different from similarly sized modern killer whales that live to 65 years, suggesting that unlike the latter, which are apex predators, these physeteroids were subject to predation from larger species such as megalodon or Livyatan.[69] By the Late Miocene, around 11 mya, macroraptorials experienced a significant decline in abundance and diversity. Other species may have filled this niche in the Pliocene,[66][70] such as the fossil killer whale Orcinus citoniensis which may have been a pack predator and targeted prey larger than itself,[27][71][72][73] but this inference is disputed,[8] and it was probably a generalist predator rather than a marine mammal specialist.[74]
+
+Megalodon may have subjected contemporaneous white sharks to competitive exclusion, as the fossil records indicate that other shark species avoided regions it inhabited by mainly keeping to the colder waters of the time.[75][26]:77 In areas where their ranges seemed to have overlapped, such as in Pliocene Baja California, it is possible that megalodon and the great white shark occupied the area at different times of the year while following different migratory prey.[26]:77[76] Megalodon probably also had a tendency for cannibalism, much like contemporary sharks.[77]
+
+Sharks often employ complex hunting strategies to engage large prey animals. Great white shark hunting strategies may be similar to how megalodon hunted its large prey.[78] Megalodon bite marks on whale fossils suggests that it employed different hunting strategies against large prey than the great white shark.[43]
+
+One particular specimen–the remains of a 9-meter (30 ft) long undescribed Miocene baleen whale–provided the first opportunity to quantitatively analyze its attack behavior. Unlike great whites which target the underbelly of their prey, megalodon probably targeted the heart and lungs, with their thick teeth adapted for biting through tough bone, as indicated by bite marks inflicted to the rib cage and other tough bony areas on whale remains.[43] Furthermore, attack patterns could differ for prey of different sizes. Fossil remains of some small cetaceans, for example cetotheres, suggest that they were rammed with great force from below before being killed and eaten, based on compression fractures.[78]
+
+During the Pliocene, larger cetaceans appeared.[79] Megalodon apparently further refined its hunting strategies to cope with these large whales. Numerous fossilized flipper bones and tail vertebrae of large whales from the Pliocene have been found with megalodon bite marks, which suggests that megalodon would immobilize a large whale before killing and feeding on it.[7][43]
+
+Megalodon, like contemporaneous sharks, made use of nursery areas to birth their young in, specifically warm-water coastal environments with large amounts of food and protection from predators.[31] Nursery sites were identified in the Gatún Formation of Panama, the Calvert Formation of Maryland, Banco de Concepción in the Canary Islands,[80] and the Bone Valley Formation of Florida. Given that all extant lamniform sharks give birth to live young, this is believed to have been true of megalodon also.[81] Infant megalodons were around 3.5 meters (11 ft) at their smallest,[26]:61 and the pups were vulnerable to predation by other shark species, such as the great hammerhead shark (Sphyrna mokarran) and the snaggletooth shark (Hemipristis serra).[31] Their dietary preferences display an ontogenetic shift:[26]:65 Young megalodon commonly preyed on fish,[31] sea turtles,[60] dugongs,[17]:129 and small cetaceans; mature megalodon moved to off-shore areas and consumed large cetaceans.[26]:74–75
+
+An exceptional case in the fossil record suggests that juvenile megalodon may have occasionally attacked much larger balaenopterid whales. Three tooth marks apparently from a 4-to-7-meter (13 to 23 ft) long Pliocene shark were found on a rib from an ancestral blue or humpback whale that showed evidence of subsequent healing, which is suspected to have been inflicted by a juvenile megalodon.[82][83]
+
+The Earth experienced a number of changes during the time period megalodon existed which affected marine life. A cooling trend starting in the Oligocene 35 mya ultimately led to glaciation at the poles. Geological events changed currents and precipitation; among these were the closure of the Central American Seaway and changes in the Tethys Ocean, contributing to the cooling of the oceans. The stalling of the Gulf Stream prevented nutrient-rich water from reaching major marine ecosystems, which may have negatively affected its food sources. The largest fluctuation of sea levels in the Cenozoic era occurred in the Plio-Pleistocene, between around 5 million to 12 thousand years ago, due to the expansion of glaciers at the poles, which negatively impacted coastal environments, and may have contributed to its extinction along with those of several other marine megafaunal species.[84] These oceanographic changes, in particular the sea level drops, may have restricted many of the suitable shallow warm-water nursery sites for megalodon, hindering reproduction.[85] Nursery areas are pivotal for the survival of many shark species, in part because they protect juveniles from predation.[86][31]
+
+As its range did not apparently extend into colder waters, megalodon may not have been able to retain a significant amount of metabolic heat, so its range was restricted to shrinking warmer waters.[85][64][87] Fossil evidence confirms the absence of megalodon in regions around the world where water temperatures had significantly declined during the Pliocene.[26]:77 However, an analysis of the distribution of megalodon over time suggests that temperature change did not play a direct role in its extinction. Its distribution during the Miocene and Pliocene did not correlate with warming and cooling trends; while abundance and distribution declined during the Pliocene, megalodon did show a capacity to inhabit colder latitudes. It was found in locations with a mean temperature ranging from 12 to 27 °C (54 to 81 °F), with a total range of 1 to 33 °C (34 to 91 °F), indicating that the global extent of suitable habitat should not have been greatly affected by the temperature changes that occurred.[22] This is consistent with evidence that it was a mesotherm.[40]
+
+Marine mammals attained their greatest diversity during the Miocene,[26]:71 such as with baleen whales with over 20 recognized Miocene genera in comparison to only six extant genera.[89] Such diversity presented an ideal setting to support a super-predator such as megalodon.[26]:75 By the end of the Miocene, many species of mysticetes had gone extinct;[66] surviving species may have been faster swimmers and thus more elusive prey.[17]:46 Furthermore, after the closure of the Central American Seaway, tropical whales decreased in diversity and abundance.[87] The extinction of megalodon correlates with the decline of many small mysticete lineages, and it is possible that it was quite dependent on them as a food source.[63] Additionally, a marine megafauna extinction during the Pliocene was discovered to have eliminated 36% of all large marine species including 55% of marine mammals, 35% of seabirds, 9% of sharks, and 43% of sea turtles. The extinction was selective for endotherms and mesotherms relative to poikilotherms, implying causation by a decreased food supply[84] and thus consistent with megalodon being mesothermic.[40] Megalodon may have been too large to sustain itself on the declining marine food resources.[85] The cooling of the oceans during the Pliocene might have restricted the access of megalodon to the polar regions, depriving it of the large whales which had migrated there.[87]
+
+Competition from other predators of marine mammals, such as macropredatory sperm whales which appeared in the Miocene, and killer whales and great white sharks in the Pliocene,[66][70][90] may have also contributed to the decline and extinction of megalodon.[22][17]:46–47[85] Fossil records indicate that the new whale-eating cetaceans commonly occurred at high latitudes during the Pliocene, indicating that they could cope with the increasingly prevalent cold water temperatures; but they also occurred in the tropics (e.g., Orcinus sp. in South Africa).[70] The largest macropredatory sperm whales such as Livyatan are best known from the Miocene, but persisted into the Pliocene,[91] while others, such as Hoplocetus and Scaldicetus, survived until the early Pleistocene. These may have occupied a niche similar to that of orcas before eventually being replaced by them.[92] Recent evidence and more accurate dating methods suggest that C. megalodon may have died out earlier than surmised; fossils examined in North Pacific deposits imply the sharks became extinct around 3.6-4 million years ago. This is hypothesized to have been due to both cooling surface temperatures resulting in range fragmentation for C. megalodon as well as competition for prey with the newly evolved modern great white shark. Many of the species that served as megalodon's prey survived for significantly longer, contrary to a previous theory that all were swept away by a single marine mass extinction.[8]
+
+The extinction of megalodon set the stage for further changes in marine communities. The average body size of baleen whales increased significantly after its disappearance, although possibly due to other, climate-related, causes.[93] Conversely the increase in baleen whale size may have contributed to the extinction of megalodon, as they may have preferred to go after smaller whales; bite marks on large whale species may have come from scavenging sharks. Megalodon may have simply become coextinct with smaller whale species, such as Piscobalaena nana.[88] The extinction of megalodon had a positive impact on other apex predators of the time, such as the great white shark, in some cases spreading to regions where megalodon became absent.[22][90][94]
+
+Megalodon has been portrayed in several works of fiction, including films and novels, and continues to be a popular subject for fiction involving sea monsters.[95] Three individual megalodon, two adults and one juvenile, were portrayed in BBC's 2003 TV documentary series Sea Monsters, where it is defined as a "hazard" of the era.[96] The History Channel's Jurassic Fight Club portrays a megalodon attacking a Brygmophyseter sperm whale in Japan.[97] Several films depict megalodon, such as Shark Attack 3: Megalodon and the Mega Shark series (for instance Mega Shark Versus Giant Octopus and Mega Shark Versus Crocosaurus).[95] The shark appears in the 2017 videogame Ark: Survival Evolved.[98] Some stories, such as Jim Shepard's Tedford and the Megalodon, portray a rediscovery of the shark.[99] Steve Alten's Meg: A Novel of Deep Terror portrays the shark having preyed on dinosaurs with its prologue and cover artwork depicting megalodon killing a Tyrannosaurus in the sea.[100] The sequels to the book also star megalodon: The Trench, Meg: Primal Waters, Meg: Hell's Aquarium, Meg: Nightstalkers, Meg: Generations, and Meg: Origins,[95] and there is a film adaptation entitled The Meg released on 10 August 2018.[101]
+
+Animal Planet's pseudo-documentary Mermaids: The Body Found included an encounter 1.6 mya between a pod of mermaids and a megalodon.[102] Later, in August 2013, the Discovery Channel opened its annual Shark Week series with another film for television, Megalodon: The Monster Shark Lives,[103] a controversial docufiction about the creature that presented alleged evidence in order to suggest that megalodon was still alive. This program received criticism for being completely fictional; for example, all of the supposed scientists depicted were paid actors. In 2014, Discovery re-aired The Monster Shark Lives, along with a new one-hour program, Megalodon: The New Evidence, and an additional fictionalized program entitled Shark of Darkness: Wrath of Submarine, resulting in further backlash from media sources and the scientific community.[43][104][105]
+
+Reports of supposedly fresh megalodon teeth, such as those made by HMS Challenger in 1873 which were erroneously dated to be around 11,000 to 24,000 years old, are probably teeth that were well-preserved by a thick mineral-crust precipitate of manganese dioxide, and so had a lower decomposition rate and retained a white color during fossilization. Fossil megalodon teeth can vary in color from off-white to dark browns and greys, and some fossil teeth may have been redeposited into a younger stratum. The claims that megalodon could remain elusive in the depths, similar to the megamouth shark which was discovered in 1976, are unlikely as the shark lived in warm coastal waters and probably could not survive in the cold and nutrient-poor deep sea environment.[106][107]
+
+Megalodon teeth are the state fossil of North Carolina.[108]

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+Megalodon (Carcharocles megalodon), meaning "big tooth", is an extinct species of shark that lived approximately 23 to 3.6 million years ago (mya), during the Early Miocene to the Pliocene.[6] It was formerly thought to be a member of the family Lamnidae and a close relative of the great white shark (Carcharodon carcharias). However, it is now classified into the extinct family Otodontidae, which diverged from the great white shark during the Early Cretaceous. Its genus placement is still debated, authors placing it in either Carcharocles, Megaselachus, Otodus, or Procarcharodon. This is because transitional fossils have been found showing that Megalodon is the final chronospecies of a lineage of giant sharks originally of the genus Otodus which evolved during the Paleocene.
+
+While regarded as one of the largest and most powerful predators to have ever lived, megalodon is known from fragmentary remains, and its appearance and maximum size are uncertain. Scientists differ on whether it would have more closely resembled a stockier version of the great white shark, the basking shark (Cetorhinus maximus) or the sand tiger shark (Carcharias taurus). Most estimates of megalodon's size extrapolate from teeth; with maximum length estimates up to 18 meters (59 ft) and average length estimates of 10.5 meters (34 ft). Estimates suggest their large jaws could exert a bite force of up to 110,000 to 180,000 newtons (25,000 to 40,000 lbf).[7] Their teeth were thick and robust, built for grabbing prey and breaking bone.
+
+Megalodon probably had a major impact on the structure of marine communities. The fossil record indicates that it had a cosmopolitan distribution. It probably targeted large prey, such as whales, seals and sea turtles. Juveniles inhabited warm coastal waters and fed on fish and small whales. Unlike the great white, which attacks prey from the soft underside, megalodon probably used its strong jaws to break through the chest cavity and puncture the heart and lungs of its prey.
+
+The animal faced competition from whale-eating cetaceans, such as Livyatan and other macroraptorial sperm whales and possibly smaller ancestral killer whales. As the shark preferred warmer waters, it is thought that oceanic cooling associated with the onset of the ice ages, coupled with the lowering of sea levels and resulting loss of suitable nursery areas, may have also contributed to its decline. A reduction in the diversity of baleen whales and a shift in their distribution toward polar regions may have reduced megalodon's primary food source. A 2019 study reviewed newer evidence suggesting that competition from the modern great white shark may have also contributed to the extinction of megalodon, coupled with range fragmentation resulting in a gradual, asynchronous extinction as a result of cooling oceans around 3.6–4 million years ago, far earlier than previously assumed.[8] The extinction of the shark appeared to affect other animals; for example, the size of baleen whales increased significantly after the shark had disappeared.
+
+According to Renaissance accounts, gigantic triangular fossil teeth often found embedded in rocky formations were once believed to be the petrified tongues, or glossopetrae, of dragons and snakes. This interpretation was corrected in 1667 by Danish naturalist Nicolas Steno, who recognized them as shark teeth, and famously produced a depiction of a shark's head bearing such teeth. He described his findings in the book The Head of a Shark Dissected, which also contained an illustration of a megalodon tooth.[9][10][11]
+
+Swiss naturalist Louis Agassiz gave this shark its initial scientific name, Carcharodon megalodon, in his 1843 work Recherches sur les poissons fossiles, based on tooth remains.[1][12] English paleontologist Edward Charlesworth in his 1837 paper used the name Carcharias megalodon, while citing Agassiz as the author, indicating that Agassiz described the species prior to 1843. English paleontologist Charles Davies Sherborn in 1928 listed an 1835 series of articles by Agassiz as the first scientific description of the shark.[13] The specific name megalodon translates to "big tooth", from Ancient Greek: μέγας, romanized: (mégas), lit. 'big, mighty' and ὀδούς (odoús), "tooth".[14][15] The teeth of megalodon are morphologically similar to those of the great white shark (Carcharodon carcharias), and on the basis of this observation, Agassiz assigned megalodon to the genus Carcharodon.[12] Though “megalodon” is an informal name for the shark, it is also often informally dubbed the "giant white shark",[16] the "megatooth shark", the "big tooth shark", or "Meg".[17]:4
+
+There was one apparent description of the shark in 1881 classifying it as Selache manzonii.[18]
+
+Otodus obliquus
+
+Carcharocles megalodon
+
+Isurus hastalis
+
+Carcharodon carcharias
+
+While the earliest megalodon remains have been reported from the Late Oligocene, around 28 million years ago (mya),[20][21] there is disagreement as to when it appeared, with dates ranging to as young as 16 mya.[22] It has been thought that megalodon became extinct around the end of the Pliocene, about 2.6 mya;[22][23] claims of Pleistocene megalodon teeth, younger than 2.6 million years old, are considered unreliable.[23] A more recent assessment moves the extinction date back to earlier in the Pliocene, 3.6 mya.[8]
+
+Megalodon is now considered to be a member of the family Otodontidae, genus Carcharocles, as opposed to its previous classification into Lamnidae, genus Carcharodon.[22][23][24][25] Megalodon's classification into Carcharodon was due to dental similarity with the great white shark, but most authors currently believe that this is due to convergent evolution. In this model, the great white shark is more closely related to the extinct broad-toothed mako (Isurus hastalis) than to megalodon, as evidenced by more similar dentition in those two sharks; megalodon teeth have much finer serrations than great white shark teeth. The great white shark is more closely related to the mako shark (Isurus spp.), with a common ancestor around 4 mya.[12][19] Proponents of the former model, wherein megalodon and the great white shark are more closely related, argue that the differences between their dentition are minute and obscure.[26]:23–25
+
+The genus Carcharocles currently contains four species: C. auriculatus, C. angustidens, C. chubutensis, and C. megalodon.[17]:30–31  The evolution of this lineage is characterized by the increase of serrations, the widening of the crown, the development of a more triangular shape, and the disappearance of the lateral cusps.[17]:28–31[27] The evolution in tooth morphology reflects a shift in predation tactics from a tearing-grasping bite to a cutting bite, likely reflecting a shift in prey choice from fish to cetaceans.[28] Lateral cusplets were finally lost in a gradual process that took roughly 12 million years during the transition between C. chubutensis and C. megalodon.[28] The genus was proposed by D. S. Jordan and H. Hannibal in 1923 to contain C. auriculatus. In the 1980s, megalodon was assigned to Carcharocles.[12][17]:30 Before this, in 1960, the genus Procarcharodon was erected by French ichthyologist Edgard Casier, which included those four sharks and was considered separate from the great white shark. It is now considered a junior synonym of Carcharocles.[17]:30 The genus Palaeocarcharodon was erected alongside Procarcharodon to represent the beginning of the lineage, and, in the model wherein megalodon and the great white shark are closely related, their last common ancestor. It is believed to be an evolutionary dead-end and unrelated to the Carcharocles sharks by authors who reject that model.[26]:70
+
+Another model of the evolution of this genus, also proposed by Casier in 1960, is that the direct ancestor of the Carcharocles is the shark Otodus obliquus, which lived from the Paleocene through the Miocene epochs, 60 mya to 13 mya.[19][27] The genus Otodus is ultimately derived from Cretolamna, a shark from the Cretaceous period.[24][29] In this model, O. obliquus evolved into O. aksuaticus, which evolved into C. auriculatus, and then into C. angustidens, and then into C. chubutensis, and then finally into C. megalodon.
+
+Another model of the evolution of Carcharocles, proposed in 2001 by paleontologist Michael Benton, is that the three other species are actually a single species of shark that gradually changed over time between the Paleocene and the Pliocene, making it a chronospecies.[17]:17[21][30] Some authors suggest that C. auriculatus, C. angustidens, and C. chubutensis should be classified as a single species in the genus Otodus, leaving C. megalodon the sole member of Carcharocles.[21][31]
+
+The genus Carcharocles may be invalid, and the shark may actually belong in the genus Otodus, making it Otodus megalodon.[4] A 1974 study on Paleogene sharks by Henri Cappetta erected the subgenus Megaselachus, classifying the shark as Otodus (Megaselachus) megalodon, along with O. (M.) chubutensis. A 2006 review of Chondrichthyes elevated Megaselachus to genus, and classified the sharks as Megaselachus megalodon and M. chubutensis.[4] The discovery of fossils assigned to the genus Megalolamna in 2016 led to a re-evaluation of Otodus, which concluded that it is paraphyletic, that is, it consists of a last common ancestor but it does not include all of its descendants. The inclusion of the Carcharocles sharks in Otodus would make it monophyletic, with the sister clade being Megalolamna.[24]
+
+One interpretation on how megalodon appeared was that it was a robust-looking shark, and may have had a similar build to the great white shark. The jaws may have been blunter and wider than the great white, and the fins would have also been similar in shape, though thicker due to its size. It may have had a pig-eyed appearance, in that it had small, deep-set eyes.[26]:64–65
+
+Another interpretation is that megalodon bore a similarity to the whale shark (Rhincodon typus) or the basking shark (Cetorhinus maximus). The tail fin would have been crescent-shaped, the anal fin and second dorsal fin would have been small, and there would have been a caudal keel present on either side of the tail fin (on the caudal peduncle). This build is common in other large aquatic animals, such as whales, tuna, and other sharks, in order to reduce drag while swimming. The head shape can vary between species as most of the drag-reducing adaptations are toward the tail-end of the animal.[17]:35–36
+
+Since Carcharocles is derived from Otodus, and the two had teeth that bear a close similarity to those of the sand tiger shark (Carcharias taurus), megalodon may have had a build more similar to the sand tiger shark than to other sharks. This is unlikely since the sand tiger shark is a carangiform swimmer which requires faster movement of the tail for propulsion through the water than the great white shark, a thunniform swimmer.[17]:35–36[32]
+
+Due to fragmentary remains, there have been many contradictory size estimates for megalodon, as they can only be drawn from fossil teeth and vertebrae.[17]:87[33] Also because of this, the great white shark is the basis of its reconstruction and size estimation,[26]:57 as it is regarded as the best analogue to megalodon.[31] Using length estimates extrapolated from 544 teeth found throughout geological time and geography, including adults and juveniles, a 2015 study estimated an average length of 10.5 meters (34 ft).[22][25] In comparison, the maximum recorded size of the great white shark is 6.1 meters (20 ft), and the whale shark (the largest living fish) can reach 18.8 m (62 ft).[34][35][36][37] It is possible that different populations of megalodon around the globe had different body sizes and behaviors due to different ecological pressures.[25] In any event, it is thought to have been the largest macropredatory shark that ever lived.[38]
+
+Mature male megalodon may have had a body mass of 12.6 to 33.9 metric tons (13.9 to 37.4 short tons), and mature females may have been 27.4 to 59.4 metric tons (30.2 to 65.5 short tons), assuming that males could range in length from 10.5 to 14.3 meters (34 to 47 ft) and females 13.3 to 17 meters (44 to 56 ft).[26]:61[7] A 2015 study linking shark size and typical swimming speed estimated that megalodon would have typically swum at 18 kilometers per hour (11 mph)–assuming that its body mass was typically 48 metric tons (53 short tons)–which is consistent with other aquatic creatures of its size, such as the fin whale (Balaenoptera physalus) which typically cruises at speeds of 14.5 to 21.5 km/h (9.0 to 13.4 mph).[39]
+
+Its large size may have been due to climatic factors and the abundance of large prey items, and it may have also been influenced by the evolution of regional endothermy (mesothermy) which would have increased its metabolic rate and swimming speed. The otodontid sharks have been considered to have been ectotherms, so on that basis megalodon would have been ectothermic. However, the largest contemporary ectothermic sharks, such as the whale shark, are filter feeders, while lamnids are now known to be regional endotherms, implying some metabolic correlations with a predatory lifestyle. These considerations, as well as tooth oxygen isotopic data and the need for higher burst swimming speeds in macropredators of endothermic prey than ectothermy would allow, imply that otodontids, including megalodon, were probably regional endotherms.[40]
+
+Gordon Hubbell from Gainesville, Florida, possesses an upper anterior megalodon tooth whose maximum height is 18.4 centimeters (7.25 in), one of the largest known tooth specimens from the shark.[41] In addition, a 2.7-by-3.4-meter (9 by 11 ft) megalodon jaw reconstruction developed by fossil hunter Vito Bertucci contains a tooth whose maximum height is reportedly over 18 centimeters (7 in).[42]
+
+The first attempt to reconstruct the jaw of megalodon was made by Bashford Dean in 1909, displayed at the American Museum of Natural History. From the dimensions of this jaw reconstruction, it was hypothesized that megalodon could have approached 30 meters (98 ft) in length. Dean had overestimated the size of the cartilage on both jaws, causing it to be too tall.[43][44]
+
+In 1973, John E. Randall, an ichthyologist, used the enamel height (the vertical distance of the blade from the base of the enamel portion of the tooth to its tip) to measure the length of the shark, yielding a maximum length of about 13 meters (43 ft).[45] However, tooth enamel height does not necessarily increase in proportion to the animal's total length.[26]:99
+
+In 1994, marine biologists Patrick J. Schembri and Stephen Papson opined that C. megalodon may have approached a maximum of around 24 to 25 meters (79 to 82 ft) in total length.[46][47]
+
+In 1996, shark researchers Michael D. Gottfried, Leonard Compagno, and S. Curtis Bowman proposed a linear relationship between a shark's total length and the height of the largest upper anterior tooth. The proposed relationship is: total length in meters = − (0.096) × [UA maximum height (mm)]-(0.22).[21][26]:60 They asserted that C. megalodon could have reached a maximum of 20.3 meters (67 ft) in total length.[7][26][48]
+
+In 2002, shark researcher Clifford Jeremiah proposed that total length was proportional to the root width of an upper anterior tooth. He claimed that for every 1 centimeter (0.39 in) of root width, there are approximately 1.4 meters (4.6 ft) of shark length. Jeremiah pointed out that the jaw perimeter of a shark is directly proportional to its total length, with the width of the roots of the largest teeth being a tool for estimating jaw perimeter. The largest tooth in Jeremiah's possession had a root width of about 12 centimeters (4.7 in), which yielded 16.5 meters (54 ft) in total length.[17]:88
+
+In 2002, paleontologist Kenshu Shimada of DePaul University proposed a linear relationship between tooth crown height and total length after conducting anatomical analysis of several specimens, allowing any sized tooth to be used. Shimada stated that the previously proposed methods were based on a less-reliable evaluation of the dental homology between megalodon and the great white shark, and that the growth rate between the crown and root is not isometric, which he considered in his model. Using this model, the upper anterior tooth possessed by Gottfried and colleagues corresponded to a total length of 15 meters (49 ft).[49] Among several specimens found in the Gatún Formation of Panama, one upper lateral tooth was used by other researchers to obtain a total length estimate of 17.9 meters (59 ft) using this method.[31][50]
+
+In 2019, Shimada revisited the size of megalodon and discouraged using non-anterior teeth for estimations, noting that the exact position of isolated non-anterior teeth is difficult to identify. Shimada stated that the maximum total length estimates, based on upper anterior teeth that are available in museums, are 14.2 and 15.3 meters (47 and 50 ft), depending on the estimation method used.[51]
+
+The most common fossils of megalodon are its teeth. Diagnostic characteristics include a triangular shape, robust structure, large size, fine serrations, a lack of lateral denticles, and a visible V-shaped neck (where the root meets the crown).[26]:55[31] The tooth met the jaw at a steep angle, similar to the great white shark. The tooth was anchored by connective tissue fibers, and the roughness of the base may have added to mechanical strength.[52] The lingual side of the tooth, the part facing the tongue, was convex; and the labial side, the other side of the tooth, was slightly convex or flat. The anterior teeth were almost perpendicular to the jaw and symmetrical, whereas the posterior teeth were slanted and asymmetrical.[53]
+
+Megalodon teeth can measure over 180 millimeters (7.1 in) in slant height (diagonal length) and are the largest of any known shark species,[17]:33 implying it was the largest of all macropredatory sharks.[38] In 1989, a nearly complete set of megalodon teeth was discovered in Saitama, Japan. Another nearly complete associated megalodon dentition was excavated from the Yorktown Formations in the United States, and served as the basis of a jaw reconstruction of megalodon at the National Museum of Natural History (USNM). Based on these discoveries, an artificial dental formula was put together for megalodon in 1996.[26]:55[54]
+
+The dental formula of megalodon is: 2.1.7.43.0.8.4. As evident from the formula, megalodon had four kinds of teeth in its jaws: anterior, intermediate, lateral, and posterior. Megalodon's intermediate tooth technically appears to be an upper anterior and is termed as "A3" because it is fairly symmetrical and does not point mesially (side of the tooth toward the midline of the jaws where the left and right jaws meet). Megalodon had a very robust dentition,[26]:20–21 and had over 250 teeth in its jaws, spanning 5 rows.[17]:iv It is possible that large megalodon individuals had jaws spanning roughly 2 meters (6.6 ft) across.[17]:129 The teeth were also serrated, which would have improved efficiency in cutting through flesh or bone.[12][17]:1 The shark may have been able to open its mouth to a 75° angle, though a reconstruction at the USNM approximates a 100° angle.[26]:63
+
+In 2008, a team of scientists led by S. Wroe conducted an experiment to determine the bite force of the great white shark, using a 2.5-meter (8.2 ft) long specimen, and then isometrically scaled the results for its maximum size and the conservative minimum and maximum body mass of megalodon. They placed the bite force of the latter between 108,514 to 182,201 newtons (24,395 to 40,960 lbf) in a posterior bite, compared to the 18,216 newtons (4,095 lbf) bite force for the largest confirmed great white shark, and 7,400 newtons (1,700 lbf) for the placoderm fish Dunkleosteus. In addition, Wroe and colleagues pointed out that sharks shake sideways while feeding, amplifying the force generated, which would probably have caused the total force experienced by prey to be higher than the estimate.[7][55]
+
+Megalodon is represented in the fossil record by teeth, vertebral centra, and coprolites.[26]:57 As with all sharks, the skeleton of megalodon was formed of cartilage rather than bone; consequently most fossil specimens are poorly preserved.[56] To support its large dentition, the jaws of megalodon would have been more massive, stouter, and more strongly developed than those of the great white, which possesses a comparatively gracile dentition. Its chondrocranium, the cartilaginous skull, would have had a blockier and more robust appearance than that of the great white. Its fins were proportional to its larger size.[26]:64–65
+
+Some fossil vertebrae have been found. The most notable example is a partially preserved vertebral column of a single specimen, excavated in the Antwerp Basin, Belgium, in 1926. It comprises 150 vertebral centra, with the centra ranging from 55 millimeters (2.2 in) to 155 millimeters (6 in) in diameter. The shark's vertebrae may have gotten much bigger, and scrutiny of the specimen revealed that it had a higher vertebral count than specimens of any known shark, possibly over 200 centra; only the great white approached it.[26]:63–65 Another partially preserved vertebral column of a megalodon was excavated from the Gram Formation in Denmark in 1983, which comprises 20 vertebral centra, with the centra ranging from 100 millimeters (4 in) to 230 millimeters (9 in) in diameter.[52]
+
+The coprolite remains of megalodon are spiral-shaped, indicating that the shark may have had a spiral valve, a corkscrew-shaped portion of the lower intestines, similar to extant lamniform sharks. Miocene coprolite remains were discovered in Beaufort County, South Carolina, with one measuring 14 cm (5.5 in).[57]
+
+Gottfried and colleagues reconstructed the entire skeleton of megalodon, which was later put on display at the Calvert Marine Museum in the United States and the Iziko South African Museum.[26]:56[27] This reconstruction is 11.3 meters (37 ft) long and represents a mature male,[26]:61 based on the ontogenetic changes a great white shark experiences over the course of its life.[26]:65
+
+Megalodon had a cosmopolitan distribution;[22][50] its fossils have been excavated from many parts of the world, including Europe, Africa, the Americas, and Australia.[26]:67[58] It most commonly occurred in subtropical to temperate latitudes.[22][26]:78 It has been found at latitudes up to 55° N; its inferred tolerated temperature range was 1–24 °C (34–75 °F).[note 1] It arguably had the capacity to endure such low temperatures due to mesothermy, the physiological capability of large sharks to conserve metabolic heat by maintaining a higher body temperature than the surrounding water.[22]
+
+Megalodon inhabited a wide range of marine environments (i.e., shallow coastal waters, areas of coastal upwelling, swampy coastal lagoons, sandy littorals, and offshore deep water environments), and exhibited a transient lifestyle. Adult megalodon were not abundant in shallow water environments, and mostly inhabited offshore areas. Megalodon may have moved between coastal and oceanic waters, particularly in different stages of its life cycle.[17]:33[60]
+
+Fossil remains show a trend for specimens to be larger on average in the southern hemisphere than in the northern, with mean lengths of 11.6 and 9.6 meters (38 and 31 ft), respectively; and also larger in the Pacific than the Atlantic, with mean lengths of 10.9 and 9.5 meters (36 and 31 ft) respectively. They do not suggest any trend of changing body size with absolute latitude, or of change in size over time (although the Carcharocles lineage in general is thought to display a trend of increasing size over time). The overall modal length has been estimated at 10.5 meters (34 ft), with the length distribution skewed towards larger individuals, suggesting an ecological or competitive advantage for larger body size.[25]
+
+Megalodon had a global distribution and fossils of the shark have been found in many places around the world, bordering all oceans of the Neogene.[61]
+
+Though sharks are generally opportunistic feeders, megalodon's great size, high-speed swimming capability, and powerful jaws, coupled with an impressive feeding apparatus, made it an apex predator capable of consuming a broad spectrum of animals. It was probably one of the most powerful predators to have existed.[26]:71–75[7] A study focusing on calcium isotopes of extinct and extant elasmobranch sharks and rays revealed that megalodon fed at a higher trophic level than the contemporaneous great white shark. That is to say it was higher up in the food chain.[62]
+
+Fossil evidence indicates that megalodon preyed upon many cetacean species, such as dolphins, small whales, cetotheres, squalodontids (shark toothed dolphins), sperm whales, bowhead whales, and rorquals.[43][63][64] In addition to this, they also targeted seals, sirenians, and sea turtles.[60] The shark was an opportunist and piscivorous, and it would have also gone after smaller fish and other sharks.[43] Many whale bones have been found with deep gashes most likely made by their teeth.[26]:75 Various excavations have revealed megalodon teeth lying close to the chewed remains of whales,[26]:75[27] and sometimes in direct association with them.[16]
+
+The feeding ecology of megalodon appears to have varied with age and between sites, like the modern great white. It is plausible that the adult megalodon population off the coast of Peru targeted primarily cetothere whales 2.5 to 7 meters (8.2 to 23 ft) in length and other prey smaller than itself, rather than large whales in the same size class as themselves.[63] Meanwhile, juveniles likely had a diet that consisted more of fish.[31][65]
+
+Megalodon faced a highly competitive environment.[66] Its position at the top of the food chain,[67] probably had a significant impact on the structuring of marine communities.[66][68] Fossil evidence indicates a correlation between megalodon and the emergence and diversification of cetaceans and other marine mammals.[26]:78[66] Juvenile megalodon preferred habitats where small cetaceans were abundant, and adult megalodon preferred habitats where large cetaceans were abundant. Such preferences may have developed shortly after they appeared in the Oligocene.[26]:74–75
+
+Megalodon were contemporaneous with whale-eating toothed whales (particularly macroraptorial sperm whales and squalodontids), which were also probably among the era's apex predators, and provided competition.[66] Some attained gigantic sizes, such as Livyatan, which grew from 13.5 to 17.5 meters (44 to 57 ft). Fossilized teeth of an undetermined species of such physeteroids from Lee Creek Mine, North Carolina, indicate it had a maximum body length of 8–10 m and a maximum lifespan of about 25 years. This is very different from similarly sized modern killer whales that live to 65 years, suggesting that unlike the latter, which are apex predators, these physeteroids were subject to predation from larger species such as megalodon or Livyatan.[69] By the Late Miocene, around 11 mya, macroraptorials experienced a significant decline in abundance and diversity. Other species may have filled this niche in the Pliocene,[66][70] such as the fossil killer whale Orcinus citoniensis which may have been a pack predator and targeted prey larger than itself,[27][71][72][73] but this inference is disputed,[8] and it was probably a generalist predator rather than a marine mammal specialist.[74]
+
+Megalodon may have subjected contemporaneous white sharks to competitive exclusion, as the fossil records indicate that other shark species avoided regions it inhabited by mainly keeping to the colder waters of the time.[75][26]:77 In areas where their ranges seemed to have overlapped, such as in Pliocene Baja California, it is possible that megalodon and the great white shark occupied the area at different times of the year while following different migratory prey.[26]:77[76] Megalodon probably also had a tendency for cannibalism, much like contemporary sharks.[77]
+
+Sharks often employ complex hunting strategies to engage large prey animals. Great white shark hunting strategies may be similar to how megalodon hunted its large prey.[78] Megalodon bite marks on whale fossils suggests that it employed different hunting strategies against large prey than the great white shark.[43]
+
+One particular specimen–the remains of a 9-meter (30 ft) long undescribed Miocene baleen whale–provided the first opportunity to quantitatively analyze its attack behavior. Unlike great whites which target the underbelly of their prey, megalodon probably targeted the heart and lungs, with their thick teeth adapted for biting through tough bone, as indicated by bite marks inflicted to the rib cage and other tough bony areas on whale remains.[43] Furthermore, attack patterns could differ for prey of different sizes. Fossil remains of some small cetaceans, for example cetotheres, suggest that they were rammed with great force from below before being killed and eaten, based on compression fractures.[78]
+
+During the Pliocene, larger cetaceans appeared.[79] Megalodon apparently further refined its hunting strategies to cope with these large whales. Numerous fossilized flipper bones and tail vertebrae of large whales from the Pliocene have been found with megalodon bite marks, which suggests that megalodon would immobilize a large whale before killing and feeding on it.[7][43]
+
+Megalodon, like contemporaneous sharks, made use of nursery areas to birth their young in, specifically warm-water coastal environments with large amounts of food and protection from predators.[31] Nursery sites were identified in the Gatún Formation of Panama, the Calvert Formation of Maryland, Banco de Concepción in the Canary Islands,[80] and the Bone Valley Formation of Florida. Given that all extant lamniform sharks give birth to live young, this is believed to have been true of megalodon also.[81] Infant megalodons were around 3.5 meters (11 ft) at their smallest,[26]:61 and the pups were vulnerable to predation by other shark species, such as the great hammerhead shark (Sphyrna mokarran) and the snaggletooth shark (Hemipristis serra).[31] Their dietary preferences display an ontogenetic shift:[26]:65 Young megalodon commonly preyed on fish,[31] sea turtles,[60] dugongs,[17]:129 and small cetaceans; mature megalodon moved to off-shore areas and consumed large cetaceans.[26]:74–75
+
+An exceptional case in the fossil record suggests that juvenile megalodon may have occasionally attacked much larger balaenopterid whales. Three tooth marks apparently from a 4-to-7-meter (13 to 23 ft) long Pliocene shark were found on a rib from an ancestral blue or humpback whale that showed evidence of subsequent healing, which is suspected to have been inflicted by a juvenile megalodon.[82][83]
+
+The Earth experienced a number of changes during the time period megalodon existed which affected marine life. A cooling trend starting in the Oligocene 35 mya ultimately led to glaciation at the poles. Geological events changed currents and precipitation; among these were the closure of the Central American Seaway and changes in the Tethys Ocean, contributing to the cooling of the oceans. The stalling of the Gulf Stream prevented nutrient-rich water from reaching major marine ecosystems, which may have negatively affected its food sources. The largest fluctuation of sea levels in the Cenozoic era occurred in the Plio-Pleistocene, between around 5 million to 12 thousand years ago, due to the expansion of glaciers at the poles, which negatively impacted coastal environments, and may have contributed to its extinction along with those of several other marine megafaunal species.[84] These oceanographic changes, in particular the sea level drops, may have restricted many of the suitable shallow warm-water nursery sites for megalodon, hindering reproduction.[85] Nursery areas are pivotal for the survival of many shark species, in part because they protect juveniles from predation.[86][31]
+
+As its range did not apparently extend into colder waters, megalodon may not have been able to retain a significant amount of metabolic heat, so its range was restricted to shrinking warmer waters.[85][64][87] Fossil evidence confirms the absence of megalodon in regions around the world where water temperatures had significantly declined during the Pliocene.[26]:77 However, an analysis of the distribution of megalodon over time suggests that temperature change did not play a direct role in its extinction. Its distribution during the Miocene and Pliocene did not correlate with warming and cooling trends; while abundance and distribution declined during the Pliocene, megalodon did show a capacity to inhabit colder latitudes. It was found in locations with a mean temperature ranging from 12 to 27 °C (54 to 81 °F), with a total range of 1 to 33 °C (34 to 91 °F), indicating that the global extent of suitable habitat should not have been greatly affected by the temperature changes that occurred.[22] This is consistent with evidence that it was a mesotherm.[40]
+
+Marine mammals attained their greatest diversity during the Miocene,[26]:71 such as with baleen whales with over 20 recognized Miocene genera in comparison to only six extant genera.[89] Such diversity presented an ideal setting to support a super-predator such as megalodon.[26]:75 By the end of the Miocene, many species of mysticetes had gone extinct;[66] surviving species may have been faster swimmers and thus more elusive prey.[17]:46 Furthermore, after the closure of the Central American Seaway, tropical whales decreased in diversity and abundance.[87] The extinction of megalodon correlates with the decline of many small mysticete lineages, and it is possible that it was quite dependent on them as a food source.[63] Additionally, a marine megafauna extinction during the Pliocene was discovered to have eliminated 36% of all large marine species including 55% of marine mammals, 35% of seabirds, 9% of sharks, and 43% of sea turtles. The extinction was selective for endotherms and mesotherms relative to poikilotherms, implying causation by a decreased food supply[84] and thus consistent with megalodon being mesothermic.[40] Megalodon may have been too large to sustain itself on the declining marine food resources.[85] The cooling of the oceans during the Pliocene might have restricted the access of megalodon to the polar regions, depriving it of the large whales which had migrated there.[87]
+
+Competition from other predators of marine mammals, such as macropredatory sperm whales which appeared in the Miocene, and killer whales and great white sharks in the Pliocene,[66][70][90] may have also contributed to the decline and extinction of megalodon.[22][17]:46–47[85] Fossil records indicate that the new whale-eating cetaceans commonly occurred at high latitudes during the Pliocene, indicating that they could cope with the increasingly prevalent cold water temperatures; but they also occurred in the tropics (e.g., Orcinus sp. in South Africa).[70] The largest macropredatory sperm whales such as Livyatan are best known from the Miocene, but persisted into the Pliocene,[91] while others, such as Hoplocetus and Scaldicetus, survived until the early Pleistocene. These may have occupied a niche similar to that of orcas before eventually being replaced by them.[92] Recent evidence and more accurate dating methods suggest that C. megalodon may have died out earlier than surmised; fossils examined in North Pacific deposits imply the sharks became extinct around 3.6-4 million years ago. This is hypothesized to have been due to both cooling surface temperatures resulting in range fragmentation for C. megalodon as well as competition for prey with the newly evolved modern great white shark. Many of the species that served as megalodon's prey survived for significantly longer, contrary to a previous theory that all were swept away by a single marine mass extinction.[8]
+
+The extinction of megalodon set the stage for further changes in marine communities. The average body size of baleen whales increased significantly after its disappearance, although possibly due to other, climate-related, causes.[93] Conversely the increase in baleen whale size may have contributed to the extinction of megalodon, as they may have preferred to go after smaller whales; bite marks on large whale species may have come from scavenging sharks. Megalodon may have simply become coextinct with smaller whale species, such as Piscobalaena nana.[88] The extinction of megalodon had a positive impact on other apex predators of the time, such as the great white shark, in some cases spreading to regions where megalodon became absent.[22][90][94]
+
+Megalodon has been portrayed in several works of fiction, including films and novels, and continues to be a popular subject for fiction involving sea monsters.[95] Three individual megalodon, two adults and one juvenile, were portrayed in BBC's 2003 TV documentary series Sea Monsters, where it is defined as a "hazard" of the era.[96] The History Channel's Jurassic Fight Club portrays a megalodon attacking a Brygmophyseter sperm whale in Japan.[97] Several films depict megalodon, such as Shark Attack 3: Megalodon and the Mega Shark series (for instance Mega Shark Versus Giant Octopus and Mega Shark Versus Crocosaurus).[95] The shark appears in the 2017 videogame Ark: Survival Evolved.[98] Some stories, such as Jim Shepard's Tedford and the Megalodon, portray a rediscovery of the shark.[99] Steve Alten's Meg: A Novel of Deep Terror portrays the shark having preyed on dinosaurs with its prologue and cover artwork depicting megalodon killing a Tyrannosaurus in the sea.[100] The sequels to the book also star megalodon: The Trench, Meg: Primal Waters, Meg: Hell's Aquarium, Meg: Nightstalkers, Meg: Generations, and Meg: Origins,[95] and there is a film adaptation entitled The Meg released on 10 August 2018.[101]
+
+Animal Planet's pseudo-documentary Mermaids: The Body Found included an encounter 1.6 mya between a pod of mermaids and a megalodon.[102] Later, in August 2013, the Discovery Channel opened its annual Shark Week series with another film for television, Megalodon: The Monster Shark Lives,[103] a controversial docufiction about the creature that presented alleged evidence in order to suggest that megalodon was still alive. This program received criticism for being completely fictional; for example, all of the supposed scientists depicted were paid actors. In 2014, Discovery re-aired The Monster Shark Lives, along with a new one-hour program, Megalodon: The New Evidence, and an additional fictionalized program entitled Shark of Darkness: Wrath of Submarine, resulting in further backlash from media sources and the scientific community.[43][104][105]
+
+Reports of supposedly fresh megalodon teeth, such as those made by HMS Challenger in 1873 which were erroneously dated to be around 11,000 to 24,000 years old, are probably teeth that were well-preserved by a thick mineral-crust precipitate of manganese dioxide, and so had a lower decomposition rate and retained a white color during fossilization. Fossil megalodon teeth can vary in color from off-white to dark browns and greys, and some fossil teeth may have been redeposited into a younger stratum. The claims that megalodon could remain elusive in the depths, similar to the megamouth shark which was discovered in 1976, are unlikely as the shark lived in warm coastal waters and probably could not survive in the cold and nutrient-poor deep sea environment.[106][107]
+
+Megalodon teeth are the state fossil of North Carolina.[108]

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+
+Melbourne (/ˈmɛlbərn/ (listen) MEL-bərn [note 1], Kulin: Naarm) is the capital and most populous city of the Australian state of Victoria, and the second most populous city in Australia and Oceania.[1] Its name refers to an urban agglomeration of 9,993 km2 (3,858 sq mi),[10] comprising a metropolitan area with 31 municipalities,[11] and is also a common name for its city centre. The city occupies much of the coastline of Port Phillip bay and spreads into the Hinterland towards the Dandenong and Macedon ranges, Mornington Peninsula and Yarra Valley. It has a population of 5 million (19% of the population of Australia), and its inhabitants are referred to as "Melburnians".[note 2]
+
+Home to Indigenous Australians for over 40,000 years, the Melbourne area served as a popular meeting place for local Kulin nation clans. A short-lived penal settlement was established at Port Phillip, then part of the British colony of New South Wales, in 1803, but it was not until 1835, with the arrival of free settlers from Van Diemen’s Land (modern-day Tasmania), that Melbourne was founded.[14] It was incorporated as a Crown settlement in 1837, and named Melbourne by Governor General Richard Bourke on 10 April 1837[15] in honour of the then British Prime Minister, William Lamb, 2nd Viscount Melbourne.[14] In 1851, four years after Queen Victoria declared it a city, Melbourne became the capital of the new colony of Victoria.[16] In the wake of the 1850s Victorian gold rush, the city entered a lengthy boom period that, by the late 1880s, had transformed it into one of the world's largest and wealthiest metropolises.[17][18] After the federation of Australia in 1901, it served as the interim seat of government of the new nation until Canberra became the permanent capital in 1927.[19] Today, it is a leading financial centre in the Asia-Pacific region and ranks 15th in the Global Financial Centres Index.[20]
+
+Melbourne is home to many of Australia's best-known landmarks, such as the Melbourne Cricket Ground, the National Gallery of Victoria and the World Heritage-listed Royal Exhibition Building. Noted for its cultural heritage, the city gave rise to Australian rules football, Australian impressionism and Australian cinema, and has more recently been recognised as a UNESCO City of Literature and a global centre for street art, live music and theatre. It hosts major annual international events, such as the Australian Grand Prix and the Australian Open, and also hosted the 1956 Summer Olympics and the 2006 Commonwealth Games. Melbourne consistently ranked as the world's most liveable city for much of the 2010s.[21]
+
+Melbourne Airport, also known as Tullamarine Airport, is the second busiest airport in Australia, and the city's port is the nation's busiest seaport.[22] Its main metropolitan rail terminus is Flinders Street station and its main regional rail and road coach terminus is Southern Cross station. It also has Australia's most extensive freeway network and the largest urban tram network in the world.[23]
+
+Indigenous Australians have lived in the Melbourne area for at least 40,000 years.[24] When European settlers arrived in the 19th century, at least 20,000 Kulin people from three distinct language groups — the Wurundjeri, Boonwurrung and Wathaurong — resided in the area.[25][26] It was an important meeting place for the clans of the Kulin nation alliance and a vital source of food and water.[27][28]
+
+The first British settlement in Victoria, then part of the penal colony of New South Wales, was established by Colonel David Collins in October 1803, at Sullivan Bay, near present-day Sorrento. The following year, due to a perceived lack of resources, these settlers relocated to Van Diemen's Land (present-day Tasmania) and founded the city of Hobart.
+It would be 30 years before another settlement was attempted.[29]
+
+In May and June 1835, John Batman, a leading member of the Port Phillip Association in Van Diemen's Land, explored the Melbourne area, and later claimed to have negotiated a purchase of 600,000 acres (2,400 km2) with eight Wurundjeri elders.[27][28] Batman selected a site on the northern bank of the Yarra River, declaring that "this will be the place for a village" before returning to Van Diemen's Land.[30] In August 1835, another group of Vandemonian settlers arrived in the area and established a settlement at the site of the current Melbourne Immigration Museum. Batman and his group arrived the following month and the two groups ultimately agreed to share the settlement, initially known by the native name of Dootigala.[31][32]
+
+Batman's Treaty with the Aborigines was annulled by Richard Bourke, the Governor of New South Wales (who at the time governed all of eastern mainland Australia), with compensation paid to members of the association.[27] In 1836, Bourke declared the city the administrative capital of the Port Phillip District of New South Wales, and commissioned the first plan for its urban layout, the Hoddle Grid, in 1837.[33] Known briefly as Batmania,[34] the settlement was named Melbourne on 10 April 1837 by Governor Richard Bourke[15] after the British Prime Minister, William Lamb, 2nd Viscount Melbourne, whose seat was Melbourne Hall in the market town of Melbourne, Derbyshire. That year, the settlement's general post office officially opened with that name.[35]
+
+Between 1836 and 1842, Victorian Aboriginal groups were largely dispossessed of their land by European settlers.[36] By January 1844, there were said to be 675 Aborigines resident in squalid camps in Melbourne.[37] The British Colonial Office appointed five Aboriginal Protectors for the Aborigines of Victoria, in 1839, however their work was nullified by a land policy that favoured squatters who took possession of Aboriginal lands.[38] By 1845, fewer than 240 wealthy Europeans held all the pastoral licences then issued in Victoria and became a powerful political and economic force in Victoria for generations to come.[39]
+
+Letters patent of Queen Victoria, issued on 25 June 1847, declared Melbourne a city.[16] On 1 July 1851, the Port Phillip District separated from New South Wales to become the Colony of Victoria, with Melbourne as its capital.[40]
+
+The discovery of gold in Victoria in mid-1851 sparked a gold rush, and Melbourne, the colony's major port, experienced rapid growth. Within months, the city's population had nearly doubled from 25,000 to 40,000 inhabitants.[41] Exponential growth ensued, and by 1865 Melbourne had overtaken Sydney as Australia's most populous city.[42]
+
+An influx of intercolonial and international migrants, particularly from Europe and China, saw the establishment of slums, including Chinatown and a temporary "tent city" on the southern banks of the Yarra. In the aftermath of the 1854 Eureka Rebellion, mass public-support for the plight of the miners resulted in major political changes to the colony, including improvements in working conditions across mining, agriculture, manufacturing and other local industries. At least twenty nationalities took part in the rebellion, giving some indication of immigration flows at the time.[43]
+
+With the wealth brought in from the gold rush and the subsequent need for public buildings, a program of grand civic construction soon began. The 1850s and 1860s saw the commencement of Parliament House, the Treasury Building, the Old Melbourne Gaol, Victoria Barracks, the State Library, University of Melbourne, General Post Office, Customs House, the Melbourne Town Hall, St Patrick's cathedral, though many remained uncompleted for decades, with some still not finished as of 2018[update].
+
+The layout of the inner suburbs on a largely one-mile grid pattern, cut through by wide radial boulevards and parklands surrounding the central city, was largely established[by whom?] in the 1850s and 1860s. These areas rapidly filled with the ubiquitous terrace houses, as well as with detached houses and grand mansions, while some of the major roads developed as shopping streets. Melbourne quickly became a major finance centre, home to several banks, the Royal Mint, and (in 1861) Australia's first stock exchange.[44]
+In 1855, the Melbourne Cricket Club secured possession of its now famous ground, the MCG. Members of the Melbourne Football Club codified Australian football in 1859,[45] and in 1861, the first Melbourne Cup race was held. Melbourne acquired its first public monument, the Burke and Wills statue, in 1864.
+
+With the gold rush largely over by 1860, Melbourne continued to grow on the back of continuing gold-mining, as the major port for exporting the agricultural products of Victoria (especially wool) and with a developing manufacturing sector protected by high tariffs. An extensive radial railway network spread into the countryside from the late 1850s. Construction started on further major public buildings in the 1860s and 1870s, such as the Supreme Court, Government House, and the Queen Victoria Market. The central city filled up with shops and offices, workshops, and warehouses. Large banks and hotels faced the main streets, with fine townhouses in the east end of Collins Street, contrasting with tiny cottages down laneways within the blocks. The Aboriginal population continued to decline, with an estimated 80% total decrease by 1863, due primarily to introduced diseases (particularly smallpox[25]), frontier violence and dispossession of their lands.
+
+The decade of the 1880s saw extraordinary growth: consumer confidence, easy access to credit, and steep increases in land prices led to an enormous amount of construction. During this "land boom", Melbourne reputedly became the richest city in the world,[17] and the second-largest (after London) in the British Empire.[46]
+
+The decade began with the Melbourne International Exhibition in 1880, held in the large purpose-built Exhibition Building. In 1880 a telephone exchange was established, and in the same year the foundations of St Paul's, were laid; in 1881 electric light was installed in the Eastern Market, and in the following year a generating station capable of supplying 2,000 incandescent lamps was in operation.[47] In 1885 the Melbourne Tramway Trust built the first line of the Melbourne cable tramway system, which became one of the world's most extensive systems by 1890.
+
+In 1885 visiting English journalist George Augustus Henry Sala coined the phrase "Marvellous Melbourne", which stuck long into the twentieth century and which Melburnians still use today.[48] Melbourne's land-boom reached a peak in 1888, fuelled by consumer confidence and escalating land-value.[49] As a result of the boom, large commercial buildings, grand edifices, banks, coffee palaces, terrace housing and palatial mansions proliferated in the city.[49] The establishment of a hydraulic facility in 1887 allowed for the local manufacture of elevators, resulting in the first construction of high-rise buildings;[50][failed verification] most notably the APA Building, amongst the world's tallest commercial buildings upon completion in 1889.[49] This period also saw the expansion of a major radial rail-based transport network.[51]
+
+In 1888 the Exhibition Building hosted a second event, even larger than the first: the Melbourne Centennial Exhibition. This spurred the construction of numerous hotels, including the 500-room Federal Hotel, The Palace Hotel in Bourke Street (both since demolished), and the doubling in size of the Grand (Windsor).[citation needed]
+
+A brash boosterism that had typified Melbourne during this time ended in the early 1890s with a severe economic depression, sending the local finance- and property-industries into a period of chaos,[49][52] during which 16 small "land banks" and building societies collapsed, and 133 limited companies went into liquidation. The Melbourne financial crisis was a contributing factor in the Australian economic depression of the 1890s and in the Australian banking crisis of 1893. The effects of the depression on the city were profound, with virtually no new construction until the late 1890s.[53][54]
+
+At the time of Australia's federation on 1 January 1901, Melbourne became the seat of government of the federation. The first federal parliament was convened on 9 May 1901 in the Royal Exhibition Building, subsequently moving to the Victorian Parliament House where it was located until 1927, when it was moved to Canberra. The Governor-General of Australia resided at Government House in Melbourne until 1930 and many major national institutions remained in Melbourne well into the twentieth century.[55]
+
+In the immediate years after World War II, Melbourne expanded rapidly, its growth boosted by post-war immigration to Australia, primarily from Southern Europe and the Mediterranean.[56] While the "Paris End" of Collins Street began Melbourne's boutique shopping and open air cafe cultures,[57] the city centre was seen by many as stale—the dreary domain of office workers—something expressed by John Brack in his famous painting Collins St., 5 pm (1955).[58] Up until the 21st century, Melbourne was considered Australia's "industrial heartland".[59]
+
+Height limits in the CBD were lifted in 1958, after the construction of ICI House, transforming the city's skyline with the introduction of skyscrapers. Suburban expansion then intensified, served by new indoor malls beginning with Chadstone Shopping Centre.[60] The post-war period also saw a major renewal of the CBD and St Kilda Road which significantly modernised the city.[61] New fire regulations and redevelopment saw most of the taller pre-war CBD buildings either demolished or partially retained through a policy of facadism. Many of the larger suburban mansions from the boom era were also either demolished or subdivided.
+
+To counter the trend towards low-density suburban residential growth, the government began a series of controversial public housing projects in the inner city by the Housing Commission of Victoria, which resulted in demolition of many neighbourhoods and a proliferation of high-rise towers.[62] In later years, with the rapid rise of motor vehicle ownership, the investment in freeway and highway developments greatly accelerated the outward suburban sprawl and declining inner city population. The Bolte government sought to rapidly accelerate the modernisation of Melbourne. Major road projects including the remodelling of St Kilda Junction, the widening of Hoddle Street and then the extensive 1969 Melbourne Transportation Plan changed the face of the city into a car-dominated environment.[63]
+
+Australia's financial and mining booms during 1969 and 1970 resulted in establishment of the headquarters of many major companies (BHP Billiton and Rio Tinto, among others) in the city. Nauru's then booming economy resulted in several ambitious investments in Melbourne, such as Nauru House.[64] Melbourne remained Australia's main business and financial centre until the late 1970s, when it began to lose this primacy to Sydney.[65]
+
+Melbourne experienced an economic downturn between 1989 and 1992, following the collapse of several local financial institutions. In 1992, the newly elected Kennett government began a campaign to revive the economy with an aggressive development campaign of public works coupled with the promotion of the city as a tourist destination with a focus on major events and sports tourism.[66] During this period the Australian Grand Prix moved to Melbourne from Adelaide. Major projects included the construction of a new facility for the Melbourne Museum, Federation Square, the Melbourne Exhibition and Convention Centre, Crown Casino and the CityLink tollway. Other strategies included the privatisation of some of Melbourne's services, including power and public transport, and a reduction in funding to public services such as health, education and public transport infrastructure.[67]
+
+Since the mid-1990s, Melbourne has maintained significant population and employment growth. There has been substantial international investment in the city's industries and property market. Major inner-city urban renewal has occurred in areas such as Southbank, Port Melbourne, Melbourne Docklands and more recently, South Wharf. Melbourne sustained the highest population increase and economic growth rate of any Australian capital city from 2001 to 2004.[68]
+
+From 2006, the growth of the city extended into "green wedges" and beyond the city's urban growth boundary. Predictions of the city's population reaching 5 million people pushed the state government to review the growth boundary in 2008 as part of its Melbourne @ Five Million strategy.[69] In 2009, Melbourne was less affected by the late-2000s financial crisis in comparison to other Australian cities. At this time, more new jobs were created in Melbourne than any other Australian city—almost as many as the next two fastest growing cities, Brisbane and Perth, combined,[70] and Melbourne's property market remained highly priced,[71] resulting in historically high property prices and widespread rent increases.[72] In 2018, Melbourne was classified as an Alpha city by the Globalization and World Cities Research Network.[73]
+
+Melbourne is in the southeastern part of mainland Australia, within the state of Victoria. Geologically, it is built on the confluence of Quaternary lava flows to the west, Silurian mudstones to the east, and Holocene sand accumulation to the southeast along Port Phillip. The southeastern suburbs are situated on the Selwyn fault which transects Mount Martha and Cranbourne.
+
+Melbourne extends along the Yarra River towards the Yarra Valley and the Dandenong Ranges to the east. It extends northward through the undulating bushland valleys of the Yarra's tributaries—Moonee Ponds Creek (toward Tullamarine Airport), Merri Creek, Darebin Creek and Plenty River—to the outer suburban growth corridors of Craigieburn and Whittlesea.
+
+The city reaches southeast through Dandenong to the growth corridor of Pakenham towards West Gippsland, and southward through the Dandenong Creek valley and the city of Frankston. In the west, it extends along the Maribyrnong River and its tributaries north towards Sunbury and the foothills of the Macedon Ranges, and along the flat volcanic plain country towards Melton in the west, Werribee at the foothills of the You Yangs granite ridge south west of the CBD. The Little River, and the township of the same name, marks the border between Melbourne and neighbouring Geelong city.
+
+Melbourne's major bayside beaches are in the various suburbs along the shores of Port Phillip Bay, in areas like Port Melbourne, Albert Park, St Kilda, Elwood, Brighton, Sandringham, Mentone, Frankston, Altona, Williamstown and Werribee South. The nearest surf beaches are 85 kilometres (53 mi) south of the Melbourne CBD in the back-beaches of Rye, Sorrento and Portsea.[74][75]
+
+Melbourne has a temperate oceanic climate (Köppen climate classification Cfb) with warm to hot summers and mild winters.[76][77] Melbourne is well known for its changeable weather conditions, mainly due to it being located on the boundary of hot inland areas and the cool southern ocean. This temperature differential is most pronounced in the spring and summer months and can cause strong cold fronts to form. These cold fronts can be responsible for varied forms of severe weather from gales to thunderstorms and hail, large temperature drops and heavy rain. Winters, however, are usually very stable, but rather damp and often cloudy.
+
+Port Phillip is often warmer than the surrounding oceans and/or the land mass, particularly in spring and autumn; this can set up a "bay effect" similar to the "lake effect" seen in colder climates where showers are intensified leeward of the bay. Relatively narrow streams of heavy showers can often affect the same places (usually the eastern suburbs) for an extended period, while the rest of Melbourne and surrounds stays dry. Overall, Melbourne is, owing to the rain shadow of the Otway Ranges, nonetheless drier than average for southern Victoria. Within the city and surrounds, rainfall varies widely, from around 425 millimetres (17 in) at Little River to 1,250 millimetres (49 in) on the eastern fringe at Gembrook. Melbourne receives 48.6 clear days annually. Dewpoint temperatures in the summer range from 9.5 to 11.7 °C (49.1 to 53.1 °F).[78]
+
+Melbourne is also prone to isolated convective showers forming when a cold pool crosses the state, especially if there is considerable daytime heating. These showers are often heavy and can include hail, squalls, and significant drops in temperature, but they often pass through very quickly with a rapid clearing trend to sunny and relatively calm weather and the temperature rising back to what it was before the shower. This can occur in the space of minutes and can be repeated many times a day, giving Melbourne a reputation for having "four seasons in one day",[79] a phrase that is part of local popular culture.[80] The lowest temperature on record is −2.8 °C (27.0 °F), on 21 July 1869.[81] The highest temperature recorded in Melbourne city was 46.4 °C (115.5 °F), on 7 February 2009.[82] While snow is occasionally seen at higher elevations in the outskirts of the city, it has not been recorded in the Central Business District since 1986.[83]
+
+The average temperature of the sea ranges from 14.6 °C (58.3 °F) in September to 18.8 °C (65.8 °F) in February;[84] at Port Melbourne, the average sea temperature range is the same.[85]
+
+Melbourne's urban area is approximately 2,453 km2, slightly larger than that of London and Mexico City,[89] while its metropolitan area is 9,993 km2 (3,858 sq mi)–larger than Jakarta (at 7,063 km2), but smaller than New York City (at 11,875 km2). The Hoddle Grid, a grid of streets measuring approximately 1 by 1⁄2 kilometre (0.62 by 0.31 mi), forms the nucleus of Melbourne's central business district (CBD). The grid's southern edge fronts onto the Yarra River. More recent office, commercial and public developments in the adjoining districts of Southbank and Docklands have made these areas into extensions of the CBD in all but name. A byproduct of the CBD's layout is its network of lanes and arcades, such as Block Arcade and Royal Arcade.[90][91]
+
+Melbourne's CBD, compared with other Australian cities, has unrestricted height limits. As a result, it has become Australia's most densely populated area with approximately 19,500 residents per square kilometre,[92] and is home to more skyscrapers than any other Australian city, the tallest being Australia 108, situated in Southbank.[93]
+
+The CBD and surrounds also contain many significant historic buildings such as the Royal Exhibition Building, the Melbourne Town Hall and Parliament House.[94][95]
+Although the area is described as the centre, it is not actually the demographic centre of Melbourne at all, due to an urban sprawl to the south east, the demographic centre being located at Glen Iris.[96]
+Melbourne is typical of Australian capital cities in that after the turn of the 20th century, it expanded with the underlying notion of a 'quarter acre home and garden' for every family, often referred to locally as the Australian Dream.[97][98] This, coupled with the popularity of the private automobile after 1945, led to the auto-centric urban structure now present today in the middle and outer suburbs. Much of metropolitan Melbourne is accordingly characterised by low density sprawl, whilst its inner city areas feature predominantly medium-density, transit-oriented urban forms. The city centre, Docklands, St. Kilda Road and Southbank areas feature high-density forms.
+
+Melbourne is often referred to as Australia's garden city, and the state of Victoria was once known as the garden state.[99][100][101] There is an abundance of parks and gardens in Melbourne,[102] many close to the CBD with a variety of common and rare plant species amid landscaped vistas, pedestrian pathways and tree-lined avenues. Melbourne's parks are often considered the best public parks in all of Australia's major cities.[103] There are also many parks in the surrounding suburbs of Melbourne, such as in the municipalities of Stonnington, Boroondara and Port Phillip, south east of the central business district. Several national parks have been designated around the urban area of Melbourne, including the Mornington Peninsula National Park, Port Phillip Heads Marine National Park and Point Nepean National Park in the southeast, Organ Pipes National Park to the north and Dandenong Ranges National Park to the east. There are also a number of significant state parks just outside Melbourne.[104][105] The extensive area covered by urban Melbourne is formally divided into hundreds of suburbs (for addressing and postal purposes), and administered as local government areas[106] 31 of which are located within the metropolitan area.[107]
+
+Melbourne has minimal public housing and high demand for rental housing, which is becoming unaffordable for some.[108][109][110] Public housing is usually provided by the Housing Commission of Victoria, and operates within the framework of the Commonwealth-State Housing Agreement, by which federal and state governments provide housing funding.
+
+Melbourne is experiencing high population growth, generating high demand for housing. This housing boom has increased house prices and rents, as well as the availability of all types of housing. Subdivision regularly occurs in the outer areas of Melbourne, with numerous developers offering house and land packages. However, after the release of Melbourne 2030 in 2002, planning policies have encouraged medium-density and high-density development in existing areas with greater access to public transport and other services, Melbourne's middle and outer-ring suburbs have seen significant brownfields redevelopment.[111]
+
+On the back of the 1850s gold rush and 1880s land boom, Melbourne became renowned as one of the world's great Victorian-era cities, a reputation that persists due to its diverse range of Victorian architecture.[112] Outside the CBD, high concentrations of well-preserved Victorian-era buildings can also be found in the inner suburbs, such as Carlton, East Melbourne and South Melbourne.[113] Outstanding examples of Melbourne's built Victorian heritage include the World Heritage-listed Royal Exhibition Building (1880), the General Post Office (1867), Hotel Windsor (1884) and the Block Arcade (1891).[114] Very little remains of Melbourne's pre-gold rush architecture; St James Old Cathedral (1839) and St Francis' Church (1845) are among the few surviving examples in the CBD.
+
+The city also features the Shrine of Remembrance, which was built as a memorial to the men and women of Victoria who served in World War I and is now a memorial to all Australians who have served in war. The now demolished Queen Anne style APA Australian Building (1889), the world's 3rd tallest building at the time of completion,[116] is erroneously said to have anticipated the skyscraper race in New York City and Chicago.[94] It was demolished in 1980 and replaced by a smaller, four-storey structure.[117] A similar fate met other grand pre-war boom-era buildings in the city, notably the elaborate Victorian Federal Coffee Palace (also known as The Federal Hotel), located on Collins Street until its demolition in 1973.[118]
+
+Residential architecture is not defined by a single architectural style, but rather an eclectic mix of large McMansion-style houses (particularly in areas of urban sprawl), apartment buildings, condominiums, and townhouses which generally characterise the medium-density inner-city neighbourhoods. Freestanding dwellings with relatively large gardens are perhaps the most common type of housing outside inner city Melbourne. Victorian terrace housing, townhouses and historic Italianate, Tudor revival and Neo-Georgian mansions are all common in inner-city neighbourhoods such as Carlton, Fitzroy and further into suburban enclaves like Toorak.[citation needed]
+
+Often referred to as Australia's cultural capital, Melbourne is recognised globally as a centre of sport, music, theatre, comedy, art, literature, film and television.[119] For much of the 2010s, it held the top position in The Economist Intelligence Unit's list of the world's most liveable cities, partly due to its cultural attributes.[21]
+
+The city celebrates a wide variety of annual cultural events and festivals of all types, including the Melbourne International Arts Festival, Melbourne International Comedy Festival, Melbourne Fringe Festival and Moomba, Australia's largest free community festival.
+
+The State Library of Victoria, founded in 1854, is one of the world's oldest free public libraries and, as of 2018, the fourth most-visited library globally.[120] Between the gold rush and the crash of 1890, Melbourne was Australia's literary capital, famously referred to by Henry Kendall as "that wild bleak Bohemia south of the Murray".[121] At this time, Melbourne-based writers and poets Marcus Clarke, Adam Lindsay Gordon and Rolf Boldrewood produced classic visions of colonial life. Fergus Hume's The Mystery of a Hansom Cab (1886), the fastest-selling crime novel of the era, is set in Melbourne, as is Australia's best-selling book of poetry, C. J. Dennis' The Songs of a Sentimental Bloke (1915).[122] Contemporary Melbourne authors who have written award-winning books set in the city include Peter Carey, Helen Garner and Christos Tsiolkas. Melbourne has Australia's widest range of bookstores, as well as the nation's largest publishing sector.[123] The city is also home to the Melbourne Writers Festival and hosts the Victorian Premier's Literary Awards. In 2008, it became the second city to be named a UNESCO City of Literature.
+
+Ray Lawler's play Summer of the Seventeenth Doll is set in Carlton and debuted in 1955, the same year that Edna Everage, Barry Humphries' Moonee Ponds housewife character, first appeared on stage, both sparking international interest in Australian theatre. Melbourne's East End Theatre District is known for its Victorian era theatres, such as the Athenaeum, Her Majesty's and the Princess, as well as the Forum and the Regent. Heritage-listed theatres outside the district include The Capitol and the art deco Palais Theatre, a St Kilda landmark and Australia's largest seated theatre with a capacity of 3,000 people.[124] The Arts Precinct in Southbank is home to Arts Centre Melbourne (which includes the State Theatre and Hamer Hall), as well as the Melbourne Recital Centre and Southbank Theatre, home of the Melbourne Theatre Company, Australia's oldest professional theatre company.[125] The Australian Ballet, Opera Australia and Melbourne Symphony Orchestra are also based in the precinct.
+
+Melbourne has been called "the live music capital of the world";[126] one study found it has more music venues per capita than any other world city sampled, with 17.5 million patron visits to 553 venues in 2016.[126][127] The Sidney Myer Music Bowl in Kings Domain hosted the largest crowd ever for a music concert in Australia when an estimated 200,000 attendees saw Melbourne band The Seekers in 1967.[128] Airing between 1974 and 1987, Melbourne's Countdown helped launch the careers of Crowded House, Men at Work and Kylie Minogue, among other local acts. Several distinct post-punk scenes flourished in Melbourne during the late 1970s, including the Fitzroy-based Little Band scene and the St Kilda scene centered at the Crystal Ballroom, which featured members of Dead Can Dance and Nick Cave and the Bad Seeds, respectively.[129] More recent independent acts from Melbourne to achieve global recognition include The Avalanches, Gotye and King Gizzard and the Lizard Wizard. Melbourne is also regarded as a centre of EDM, and lends its name to the Melbourne Bounce genre and the Melbourne Shuffle dance style, both of which emerged out of the city's underground rave scene.[130]
+
+Established in 1861, the National Gallery of Victoria is Australia's oldest and largest art museum. Several art movements originated in Melbourne, most famously the Heidelberg School of impressonists, named after a suburb where they camped to paint en plein air in the 1880s.[131] During the interwar period, the Australian tonalists emerged,[132] followed by the Angry Penguins, a group of avant-garde painters who stayed at a dairy farm in Bulleen, now the Heide Museum of Modern Art. The city is also home to the Australian Centre for Contemporary Art. Since the early 2000s, Melbourne street art has become internationally renowned and a major drawcard for tourists, with "laneway galleries" such as Hosier Lane attracting more Instagram hashtags than some of the city's traditional attractions, such as the Melbourne Zoo.[133][134]
+
+A quarter century after bushranger Ned Kelly's execution at Old Melbourne Gaol, the Melbourne-produced The Story of the Kelly Gang (1906), the world's first feature-length narrative film, premiered at the above-named Athenaeum, spurring Australia's first cinematic boom.[135] Melbourne remained a world leader in filmmaking until the mid-1910s, when several factors, including a ban on bushranger films, contributed to a decades-long decline of the industry.[135] A notable film shot and set in Melbourne during this lull was On the Beach (1959).[136] Melbourne filmmakers led the Australian Film Revival with ocker comedies such as Stork (1971) and Alvin Purple (1973).[137] Other films shot and set in Melbourne include Mad Max (1979), Romper Stomper (1992), Chopper (2000) and Animal Kingdom (2010). The Melbourne International Film Festival began in 1952 and is one of the world's oldest film festivals. The AACTA Awards, Australia's top screen awards, were inaugurated by the festival in 1958. Melbourne is also home to Docklands Studios Melbourne (the city's largest film and television studio complex),[138] the Australian Centre for the Moving Image and the headquarters of Village Roadshow Pictures, Australia's largest film production company.
+
+Melbourne has long been regarded as Australia's sporting capital due to the role it has played in the development of Australian sport, the range and quality of its sporting events and venues, and its high rates of spectatorship and participation.[139] The city is also home to 27 professional sports teams competing at the national level, the most of any Australian city. Melbourne's sporting reputation was recognised in 2016 when, after being ranked as the world's top sports city three times biennially, the Ultimate Sports City Awards in Switzerland named it 'Sports City of the Decade'.[140]
+
+The city has hosted a number of major international sporting events, most notably the 1956 Summer Olympic Games, the first Olympic Games held outside Europe and the United States.[141] Melbourne also hosted the 2006 Commonwealth Games, and is home to several major annual international events, including the Australian Open, the first of the four Grand Slam tennis tournaments. First held in 1861 and declared a public holiday for all Melburnians in 1873, the Melbourne Cup is the world's richest handicap horse race, and is known as "the race that stops a nation". The Formula One Australian Grand Prix has been held at the Albert Park Circuit since 1996.
+
+Cricket was one of the first sports to become organised in Melbourne with the Melbourne Cricket Club forming within three years of settlement. The club manages the 100,000 capacity Melbourne Cricket Ground (MCG). Established in 1853, the MCG is notable for hosting the first Test match and the first One Day International, played between Australia and England in 1877 and 1971, respectively. It is also the home of the National Sports Museum,[142] and serves as the home ground of the Victoria cricket team. At Twenty20 level, the Melbourne Stars and Melbourne Renegades compete in the Big Bash League.
+
+Australian rules football, Australia's most popular spectator sport, traces its origins to matches played in parklands next to the MCG in 1858. Its first laws were codified the following year by the Melbourne Football Club,[143] also a founding member, in 1896, of the Australian Football League (AFL), the sport's elite professional competition. Hadquartered at Docklands Stadium, the AFL fields a further eight Melbourne-based clubs: Carlton, Collingwood, Essendon, Hawthorn, North Melbourne, Richmond, St Kilda, and the Western Bulldogs.[144] The city hosts up to five AFL matches per round during the home and away season, attracting an average of 40,000 spectators per game.[145] The AFL Grand Final, traditionally held at the MCG, is the highest attended club championship event in the world.
+
+In soccer, Melbourne is represented in the A-League by Melbourne Victory and Melbourne City FC. The rugby league team Melbourne Storm plays in the National Rugby League, and in rugby union, the Melbourne Rebels and Melbourne Rising compete in the Super Rugby and National Rugby Championship competitions, respectively. North American sports have also gained popularity in Melbourne: basketball sides South East Melbourne Phoenix and Melbourne United play in the NBL; Melbourne Ice and Melbourne Mustangs play in the Australian Ice Hockey League; and Melbourne Aces plays in the Australian Baseball League. Rowing also forms part of Melbourne's sporting identity, with a number of clubs located on the Yarra River, out of which many Australian Olympians trained.
+
+Melbourne has a highly diversified economy with particular strengths in finance, manufacturing, research, IT, education, logistics, transportation and tourism. Melbourne houses the headquarters of many of Australia's largest corporations, including five of the ten largest in the country (based on revenue), and five of the largest seven in the country (based on market capitalisation)[146] (ANZ, BHP Billiton (the world's largest mining company), the National Australia Bank, CSL and Telstra, as well as such representative bodies and think tanks as the Business Council of Australia and the Australian Council of Trade Unions. Melbourne's suburbs also have the head offices of Coles Group (owner of Coles Supermarkets) and Wesfarmers companies Bunnings, Target, K-Mart and Officeworks. The city is home to Australia's second busiest seaport, after Port Botany in Sydney.[147] Melbourne Airport provides an entry point for national and international visitors, and is Australia's second busiest airport.[148]
+
+Melbourne is also an important financial centre. In the 2018 Global Financial Centres Index, Melbourne was ranked as having the 15th most competitive financial centre in the world.[149] Two of the big four banks, NAB and ANZ, are headquartered in Melbourne. The city has carved out a niche as Australia's leading centre for superannuation (pension) funds, with 40% of the total, and 65% of industry super-funds including the AU$109 billion-dollar Federal Government Future Fund. The city was rated 41st within the top 50 financial cities as surveyed by the MasterCard Worldwide Centers of Commerce Index (2008),[150] second only to Sydney (12th) in Australia. Melbourne is Australia's second-largest industrial centre.[151]
+
+It is the Australian base for a number of significant manufacturers including Boeing, truck-makers Kenworth and Iveco, Cadbury as well as Bombardier Transportation and Jayco, among many others. It is also home to a wide variety of other manufacturers, ranging from petrochemicals and pharmaceuticals to fashion garments, paper manufacturing and food processing.[153] The south-eastern suburb of Scoresby is home to Nintendo's Australian headquarters. The city also has a research and development hub for Ford Australia, as well as a global design studio and technical centre for General Motors and Toyota respectively.
+
+CSL, one of the world's top five biotech companies, and Sigma Pharmaceuticals have their headquarters in Melbourne. The two are the largest listed Australian pharmaceutical companies.[154] Melbourne has an important ICT industry that employs over 60,000 people (one third of Australia's ICT workforce), with a turnover of AU$19.8 billion and export revenues of AU615 million. In addition, tourism also plays an important role in Melbourne's economy, with about 7.6 million domestic visitors and 1.88 million international visitors in 2004.[155] Melbourne has been attracting an increasing share of domestic and international conference markets. Construction began in February 2006 of an AU$1 billion 5000-seat international convention centre, Hilton Hotel and commercial precinct adjacent to the Melbourne Exhibition and Convention Centre to link development along the Yarra River with the Southbank precinct and multibillion-dollar Docklands redevelopment.[156]
+
+The Economist Intelligence Unit ranks Melbourne as the fourth most expensive city in the world to live in according to its worldwide cost of living index in 2013.[157] The most visited attractions are: Federation Square, Queen Victoria Market, Crown Casino, Southbank, Melbourne Zoo, Melbourne Aquarium, Docklands, National Gallery of Victoria, Melbourne Museum, Melbourne Observation Deck, Arts Centre Melbourne, and the Melbourne Cricket Ground.[158]
+
+The Economist Intelligence Unit also has ranked Melbourne as the most liveable city in the world for seven consecutive years (2011-2017).[21]
+
+Melbourne is the second most visited city in Australia and the seventy-third most visited city in the world.[159] In 2018, 10.8 million domestic overnight tourists and 2.9 million international overnight tourists visited Melbourne.[160] The most visited attractions are: Federation Square, Queen Victoria Market, Crown Casino, Southbank, Melbourne Zoo, Melbourne Aquarium, Docklands, National Gallery of Victoria, Melbourne Museum, Melbourne Observation Deck, Arts Centre Melbourne, and the Melbourne Cricket Ground.[161] Luna Park, a theme park modelled on New York's Coney Island and Seattle's Luna Park,[162] is also a popular destination for visitors.[163] In its annual survey of readers, the Condé Nast Traveler magazine found that both Melbourne and Auckland were considered the world's friendliest cities in 2014. The magazine highlighted the connection the city inhabitants have to public art and the many parks across the city.[164][165] Its high liveability rankings make it one of the safest world cities for travellers.[166][167] Furthermore, the city's prevalent cafe culture, alfresco dining and diverse food culture make it a popular spot for gastronomical tourism. The city's coffee culture is largely a result of Italian immigration, but has evolved into a local passion over time.[168] It is often claimed that Pellegrini's Espresso Bar, on Bourke Street, was the first cafe to use the espresso machine in Melbourne.[169][170]
+
+In 2018, the population of the Melbourne metropolitan area was 4,963,349.[171]
+
+Although Victoria's net interstate migration has fluctuated, the population of the Melbourne statistical division has grown by about 70,000 people a year since 2005. Melbourne has now attracted the largest proportion of international overseas immigrants (48,000) finding it outpacing Sydney's international migrant intake on percentage, along with having strong interstate migration from Sydney and other capitals due to more affordable housing and cost of living.[172]
+
+In recent years, Melton, Wyndham and Casey, part of the Melbourne statistical division, have recorded the highest growth rate of all local government areas in Australia. Prior to the COVID-19 pandemic[173], Melbourne was on track to overtake Sydney in population by 2028.[174] The ABS has projected in two scenarios that Sydney will remain larger than Melbourne beyond 2056, albeit by a margin of less than 3% compared to a margin of 12% today. Melbourne's population could overtake that of Sydney by 2037[175] or 2039, according to the first scenario projected by the ABS, primarily due to greater internal migration losses assumed for Sydney.[176] Another study claims that Melbourne will surpass Sydney in population by 2040.[177]
+
+After a trend of declining population density since World War II, the city has seen increased density in the inner and western suburbs, aided in part by Victorian Government planning, such as Postcode 3000 and Melbourne 2030, which have aimed to curtail urban sprawl.[178][179] As of 2018, the CBD is the most densely populated area in Australia with more than 19,000 residents per square kilometre, and the inner city suburbs of Carlton, South Yarra, Fitzroy and Collingwood make up Victoria's top five.[180]
+
+At the 2016 census, the most commonly nominated ancestries were:[N 2][181]
+
+0.5% of the population, or 24,062 people, identified as Indigenous Australians (Aboriginal Australians and Torres Strait Islanders) in 2016.[N 4][183]
+
+Melbourne has the 10th largest immigrant population among world metropolitan areas. In Greater Melbourne at the 2016 census, 63.3% of residents were born in Australia. The other most common countries of birth were India (3.6%), Mainland China (3.5%), England (3%), Vietnam (1.8%) and New Zealand (1.8%).[184]
+
+As of the 2016 census, 62% of Melburnians speak only English at home.[184] Mandarin (4.1%), Greek (2.4%), Italian (2.3%), Vietnamese (2.3%), and Cantonese (1.7%) were the most common foreign languages spoken at home by residents of Melbourne as of 2016.[184]
+
+Melbourne has a wide range of religious faiths, the most widely held of which is Christianity. This is signified by the city's two large cathedrals—St Patrick's (Roman Catholic), and St Paul's (Anglican). Both were built in the Victorian era and are of considerable heritage significance as major landmarks of the city.[185] In recent years, Greater Melbourne's irreligious community has grown to be one of the largest in Australia.[186]
+
+According to the 2016 Census, the largest responses on religious belief in Melbourne were no religion (31.9%), Catholic (23.4%), none stated (9.1%), Anglican (7.6%), Eastern Orthodox (4.3%), Islam (4.2%), Buddhism (3.8%), Hinduism (2.9%), Uniting Church (2.3%),  Presbyterian and Reformed (1.6%), Baptist (1.3%), Sikhism (1.2%) and Judaism (0.9%).[187]
+
+Over 180,000 Muslims live in Melbourne.[187] Muslim religious life in Melbourne is centred on more than 25 mosques and a large number of prayer rooms at university campuses, workplaces and other venues.[188]
+
+As of 2000[update], Melbourne had the largest population of Polish Jews in Australia. The city was also home to the largest number of Holocaust survivors of any Australian city,[189] indeed the highest per capita outside Israel itself.[190] Reflecting this vibrant community, Melbourne has a plethora of Jewish cultural, religious and educational institutions, including over 40 synagogues and 7 full-time parochial day schools,[191] along with a local Jewish newspaper.[192]
+
+Some of Australia's most prominent and well known schools are based in Melbourne. Of the top twenty high schools in Australia according to the My Choice Schools Ranking, five are in Melbourne.[193] There has also been a rapid increase in the number of International students studying in the city. Furthermore, Melbourne was ranked the world's fourth top university city in 2008 after London, Boston and Tokyo in a poll commissioned by the Royal Melbourne Institute of Technology.[194] Melbourne is the home of seven public universities: the University of Melbourne, Monash University, Swinburne University of Technology, Deakin University, Royal Melbourne Institute of Technology (RMIT University), La Trobe University, and Victoria University.
+
+Melbourne universities have campuses all over Australia and some internationally. Swinburne University and Monash University have campuses in Malaysia, while Monash has a research centre based in Prato, Italy. The University of Melbourne, the second oldest university in Australia,[195] was ranked first among Australian universities in the 2016 THES international rankings.  In 2018 Times Higher Education Supplement ranked the University of Melbourne the 32nd best university in the world which is higher than the rankings in 2016 and 2017,[196] Monash University was ranked 80th best.[197] Both are members of the Group of Eight, a coalition of leading Australian tertiary institutions offering comprehensive and leading education.[198]
+
+As of 2017 RMIT University is ranked 17th in the world in art & design, and 28th in architecture.[199] The Swinburne University of Technology, based in the inner-city Melbourne suburb of Hawthorn, was as of 2014 ranked 76th–100th in the world for physics by the Academic Ranking of World Universities.[200] Deakin University maintains two major campuses in Melbourne and Geelong, and is the third largest university in Victoria. In recent years, the number of international students at Melbourne's universities has risen rapidly, a result of an increasing number of places being made available for them.[201] Education in Melbourne is overseen by the Victorian Department of Education and Early Childhood Development (DEECD), whose role is to 'provide policy and planning advice for the delivery of education'.[202]
+
+Melbourne is served by thirty digital free-to-air television channels:
+
+Three daily newspapers serve Melbourne: the Herald Sun (tabloid), The Age (formerly broadsheet, now compact) and The Australian (national broadsheet). Six free-to-air television stations service Greater Melbourne and Geelong: ABC Victoria, (ABV), SBS Victoria (SBS), Seven Melbourne (HSV), Nine Melbourne (GTV), Ten Melbourne (ATV), C31 Melbourne (MGV) – community television. Each station (excluding C31) broadcasts a primary channel and several multichannels. C31 is only broadcast from the transmitters at Mount Dandenong and South Yarra. Hybrid digital/print media companies such as Broadsheet and ThreeThousand are based in and primarily serve Melbourne.
+
+Television shows are produced in Melbourne, most notably Neighbours, Kath & Kim, The Secret Life of Us, Winners and Losers, Offspring, Underbelly, House Husbands, Wentworth and Miss Fisher's Murder Mysteries, along with national news-based programs such as The Project, Insiders and ABC News Breakfast. Melbourne is also known as the game show capital of Australia; productions such as Million Dollar Minute, The Chase Australia, Millionaire Hot Seat and Family Feud are all based in Melbourne. Reality television productions such as Dancing with the Stars, MasterChef, The Block and The Real Housewives of Melbourne are all filmed in and around Melbourne.
+
+Pay television in Melbourne is largely delivered through cable and satellite services. Foxtel, Optus and Fetch are the main pay television providers. Sky News and Fox Sports both have studio facilities based in Melbourne.
+
+A long list of AM and FM radio stations broadcast to greater Melbourne. These include "public" (i.e., state-owned ABC and SBS) and community stations. Many commercial stations are networked-owned: NOVA Entertainment has Nova 100 and Smooth; ARN controls Gold 104.3 and KIIS 101.1; and Southern Cross Austereo runs both Fox and Triple M. Stations from towns in regional Victoria may also be heard (e.g. 93.9 Bay FM, Geelong). Youth alternatives include ABC Triple J and youth run SYN. Triple J, and similarly PBS and Triple R, strive to play under represented music. JOY 94.9 caters for gay, lesbian, bisexual and transgender audiences. For fans of classical music there are 3MBS and ABC Classic FM. Light FM is a contemporary Christian station. AM stations include ABC: 774, Radio National, and News Radio; also Fairfax affiliates 3AW (talk) and Magic (easy listening). For sport fans and enthusiasts there is SEN 1116. Melbourne has many community run stations that serve alternative interests, such as 3CR and 3KND (Indigenous). Many suburbs have low powered community run stations serving local audiences.[204]
+
+The governance of Melbourne is split between the government of Victoria and the 27 cities and four shires that make up the metropolitan area. There is no ceremonial or political head of Melbourne, but the Lord Mayor of the City of Melbourne often fulfils such a role as a first among equals,[205] particularly when interstate or overseas.[citation needed]
+
+The local councils are responsible for providing the functions set out in the Local Government Act 1989[206] such as urban planning and waste management. Most other government services are provided or regulated by the Victorian state government, which governs from Parliament House in Spring Street. These include services associated with local government in other countries and include public transport, main roads, traffic control, policing, education above preschool level, health and planning of major infrastructure projects. The state government retains the right to override certain local government decisions, including urban planning, and Melburnian issues often feature prominently in state election.[citation needed]
+
+In 2012, Mercer Consulting ranked Melbourne's infrastructure 17th in the world, behind only one other Australian city, Sydney, which ranked 10th in the world.[207]
+
+The Government of Victoria's Department of Health and Human Services oversees about 30 public hospitals in the Melbourne metropolitan region, and 13 health services organisations.[208]
+
+There are many major medical, neuroscience and biotechnology research institutions located in Melbourne: St. Vincent's Institute of Medical Research, Australian Stem Cell Centre, the Burnet Institute, Australian Regenerative Medicine Institute, Victorian Institute of Chemical Sciences, Brain Research Institute, Peter MacCallum Cancer Centre, the Walter and Eliza Hall Institute of Medical Research, and the Melbourne Neuropsychiatry Centre.
+
+Other institutions include the Howard Florey Institute, the Murdoch Childrens Research Institute, Baker Heart and Diabetes Institute and the Australian Synchrotron.[209] Many of these institutions are associated with and are located near universities.  Melbourne also is the home of the Royal Children's Hospital and the Monash Children's Hospital.
+
+Among Australian capital cities, Melbourne ties with Canberra in first place for the highest male life expectancy (80.0 years) and ranks second behind Perth in female life expectancy (84.1 years).[210]
+
+Like many Australian cities, Melbourne has a high dependency on the automobile for transport,[211] particularly in the outer suburban areas where the largest number of cars are bought,[212] with a total of 3.6 million private vehicles using 22,320 km (13,870 mi) of road, and one of the highest lengths of road per capita in the world.[211] The early 20th century saw an increase in popularity of automobiles, resulting in large-scale suburban expansion and a tendency towards the development of urban sprawl–like all Australian cities, inhabitants would live in the suburbs and commute to the city for work.[213] By the mid 1950s there was just under 200 passenger vehicles per 1000 people, and by 2013 there was 600 passenger vehicles per 1000 people.[214] Today it has an extensive network of freeways and arterial roadways used by private vehicles including freight as well as public transport systems including buses and taxis. Major highways feeding into the city include the Eastern Freeway, Monash Freeway and West Gate Freeway (which spans the large West Gate Bridge), whilst other freeways circumnavigate the city or lead to other major cities, including CityLink (which spans the large Bolte Bridge), Eastlink, the Western Ring Road, Calder Freeway, Tullamarine Freeway (main airport link) and the Hume Freeway which links Melbourne and Sydney.[215]
+
+Melbourne has an integrated public transport system based around extensive train, tram, bus and taxi systems. Flinders Street station was the world's busiest passenger station in 1927 and Melbourne's tram network overtook Sydney's to become the world's largest in the 1940s. From the 1940s, public transport usage in Melbourne declined due to a rapid expansion of the road and freeway network, with the largest declines in tram and bus usage.[216] This decline quickened in the early 1990s due to large public transport service cuts.[216] The operations of Melbourne's public transport system was privatised in 1999 through a franchising model, with operational responsibilities for the train, tram and bus networks licensed to private companies.[217] After 1996 there was a rapid increase in public transport patronage due to growth in employment in central Melbourne, with the mode share for commuters increasing to 14.8% and 8.4% of all trips.[218][216] A target of 20% public transport mode share for Melbourne by 2020 was set by the state government in 2006.[219] Since 2006 public transport patronage has grown by over 20%.[219]
+
+The Melbourne rail network dates back to the 1850s gold rush era, and today consists of 218 suburban stations on 16 lines which radiate from the City Loop, a mostly-underground subway system around the CBD. Flinders Street station, Australia's busiest rail hub, serves the entire network, and remains a prominent Melbourne landmark and meeting place.[220] The city has rail connections with regional Victorian cities, as well as direct interstate rail services which depart from Melbourne's other major rail terminus, Southern Cross station, in Docklands. The Overland to Adelaide departs twice a week, while the XPT to Sydney departs twice daily. In the 2017–2018 financial year, the Melbourne rail network recorded 240.9 million passenger trips, the highest ridership in its history.[221] Many rail lines, along with dedicated lines and rail yards, are also used for freight.[citation needed]
+
+Melbourne's tram network dates from the 1880s land boom and, as of 2019, consists of 250 km (155.3 mi) of double track, 475 trams, 25 routes, and 1,763 tram stops,[222] making it the largest in the world.[23][223] In 2017–2018, 206.3 million passenger trips were made by tram.[221] Around 75 per cent of Melbourne's tram network shares road space with other vehicles, while the rest of the network is separated or are light rail routes.[222] Melbourne's trams are recognised as iconic cultural assets and a tourist attraction. Heritage trams operate on the free City Circle route, intended for visitors to Melbourne, and heritage restaurant trams travel through the city and surrounding areas during the evening.[224] Melbourne is currently building 50 new E Class trams with some already in service in 2014. The E Class trams are about 30 metres long and are superior to the C2 class tram of similar length. Melbourne's bus network consists of almost 300 routes which mainly service the outer suburbs and fill the gaps in the network between rail and tram services.[224][225] 127.6 million passenger trips were recorded on Melbourne's buses in 2013–2014, an increase of 10.2 percent on the previous year.[226]
+
+Ship transport is an important component of Melbourne's transport system. The Port of Melbourne is Australia's largest container and general cargo port and also its busiest. The port handled two million shipping containers in a 12-month period during 2007, making it one of the top five ports in the Southern Hemisphere.[227] Station Pier on Port Phillip Bay is the main passenger ship terminal with cruise ships and the Spirit of Tasmania ferries which cross Bass Strait to Tasmania docking there.[228] Ferries and water taxis run from berths along the Yarra River as far upstream as South Yarra and across Port Phillip Bay.
+
+Melbourne has four airports. Melbourne Airport, at Tullamarine, is the city's main international and domestic gateway and second busiest in Australia. The airport is home base for passenger airline Jetstar Airways and cargo airlines Australian air Express and Toll Priority; and is a major hub for Qantas and Virgin Australia. Avalon Airport, located between Melbourne and Geelong, is a secondary hub of Jetstar. It is also used as a freight and maintenance facility. Buses and taxis are the only forms of public transport to and from the city's main airports. Air Ambulance facilities are available for domestic and international transportation of patients.[229] Melbourne also has a significant general aviation airport, Moorabbin Airport in the city's south east that also handles a small number of passenger flights. Essendon Airport, which was once the city's main airport also handles passenger flights, general aviation and some cargo flights.[230]
+
+The city also has a bicycle sharing system that was established in 2010[231] and uses a network of marked road lanes and segregated cycle facilities.
+
+Water storage and supply for Melbourne is managed by Melbourne Water, which is owned by the Victorian Government. The organisation is also responsible for management of sewerage and the major water catchments in the region as well as the Wonthaggi desalination plant and North–South Pipeline. Water is stored in a series of reservoirs located within and outside the Greater Melbourne area. The largest dam, the Thomson River Dam, located in the Victorian Alps, is capable of holding around 60% of Melbourne's water capacity,[232] while smaller dams such as the Upper Yarra Dam, Yan Yean Reservoir, and the Cardinia Reservoir carry secondary supplies.
+
+Gas is provided by three distribution companies:
+
+Electricity is provided by five distribution companies:
+
+Numerous telecommunications companies provide Melbourne with terrestrial and mobile telecommunications services and wireless internet services and at least since 2016 Melbourne offers a free public WiFi which allows for up to 250 MB per device in some areas of the city.
+
+Melbourne has one of the lowest crime rates of any major city globally, ranking 5th in The Economist's 2017 Safe Cities Index.[233] Reports of crime in Victoria fell by 7.8 per cent in 2018 to its lowest in three years, with 5,922 cases per 100,000 people.[234] Melbourne's city centre (CBD) reported the highest incident rate of local government areas in Victoria.[234]
+
+National and ACTCanberra
+
+NSWSydney
+
+NTDarwin
+
+QLDBrisbane
+
+SAAdelaide
+
+TASHobart
+
+VICMelbourne
+
+WAPerth

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+
+A melon is any of various plants of the family Cucurbitaceae with sweet, edible, and fleshy fruit. The word "melon" can refer to either the plant or specifically to the fruit. Botanically, a melon is a kind of berry, specifically a "pepo". The word melon derives from Latin melopepo,[1][2] which is the latinization of the Greek μηλοπέπων (mēlopepōn), meaning "melon",[3] itself a compound of μῆλον (mēlon), "apple, treefruit (of any kind)"[4] and πέπων (pepōn), amongst others "a kind of gourd or melon".[5] Many different cultivars have been produced, particularly of cantaloupes.
+
+Melons originated in Africa[6] or in the hot valleys of Southwest Asia, especially Iran and India,[7][8] from where they gradually began to appear in Europe toward the end of the Western Roman Empire. Melons are known to have been grown by the ancient Egyptians. However, recent discoveries of melon seeds dated between 1350 and 1120 BC in Nuragic sacred wells  have shown that melons were first brought to Europe by the Nuragic civilization of Sardinia during the Bronze Age.[9] Melons were among the earliest plants to be domesticated in both the Old and among the first crop species brought by westerners to the New Worlds.[10] Early European settlers in the New World are recorded as growing honeydew and casaba melons as early as the 1600s.[11] A number of Native American tribes in New Mexico, including Acoma, Cochiti, Isleta, Navajo, Santo Domingo and San Felipe, maintain a tradition of growing their own characteristic melon cultivars, derived from melons originally introduced by the Spanish. Organizations like Native Seeds/SEARCH have made an effort to collect and preserve these and other heritage seeds.[12]
+
+Melons in genus Cucumis are culinary fruits, and include the majority of culinary melons. All but a handful of culinary melon varieties belong to the species Cucumis melo L.
+
+In 2018, world production of melons was 27 million tonnes, led by China with 46% of the total (table). Turkey, Iran, and India each produced more than 1 million tonnes.[29]

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+
+A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts".[1]  The combination of movements at all joints can be modeled as a single, linear element capable of changing length and rotating about an omnidirectional "hip" joint.
+
+As an anatomical animal structure it is used for locomotion. The distal end is often modified to distribute force (such as a foot). Most animals have an even number of legs.
+
+As a component of furniture, it is used for the economy of materials needed to provide the support for the useful surface such as the table top or chair seat.
+
+Many taxa are characterized by the number of legs:
+
+A leg is a structure of gross anatomy, meaning that it is large enough to be seen unaided.  The components depend on the animal.  In humans and other mammals, a leg includes the bones, muscles, tendons, ligaments, blood vessels, nerves, and skin.  In insects, the leg includes most of these things, except that insects have an exoskeleton that replaces the function of both the bones and the skin.
+
+Sometimes the end of the leg, or foot, is considered part of the leg; other times it is considered separate.  Similarly, the hip joint or other place where the leg attaches to the main body may be considered separate or part of the leg.
+
+In tetrapod anatomy, leg is used to refer to the entire limb. In human medicine the precise definition refers[2][3][4] only to the segment between the knee and the ankle. This lower segment is also called the shank,[5][6] and the front (anterior) of the segment is called the shin or pretibia.
+
+In bipedal tetrapods, the two lower limbs are referred to as the "legs" and the two upper limbs as "arms" or "wings" as the case may be.
+
+A robotic leg is moved by an actuator, which is a type of motor for moving or controlling a mechanism or system.  It is operated by a source of energy, usually in the form of an electric current, hydraulic fluid pressure or pneumatic pressure, and converts that energy into some kind of motion.
+
+A prosthetic leg, a prosthesis, is an artificial leg that is used to replace one that has been lost.

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+
+
+A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts".[1]  The combination of movements at all joints can be modeled as a single, linear element capable of changing length and rotating about an omnidirectional "hip" joint.
+
+As an anatomical animal structure it is used for locomotion. The distal end is often modified to distribute force (such as a foot). Most animals have an even number of legs.
+
+As a component of furniture, it is used for the economy of materials needed to provide the support for the useful surface such as the table top or chair seat.
+
+Many taxa are characterized by the number of legs:
+
+A leg is a structure of gross anatomy, meaning that it is large enough to be seen unaided.  The components depend on the animal.  In humans and other mammals, a leg includes the bones, muscles, tendons, ligaments, blood vessels, nerves, and skin.  In insects, the leg includes most of these things, except that insects have an exoskeleton that replaces the function of both the bones and the skin.
+
+Sometimes the end of the leg, or foot, is considered part of the leg; other times it is considered separate.  Similarly, the hip joint or other place where the leg attaches to the main body may be considered separate or part of the leg.
+
+In tetrapod anatomy, leg is used to refer to the entire limb. In human medicine the precise definition refers[2][3][4] only to the segment between the knee and the ankle. This lower segment is also called the shank,[5][6] and the front (anterior) of the segment is called the shin or pretibia.
+
+In bipedal tetrapods, the two lower limbs are referred to as the "legs" and the two upper limbs as "arms" or "wings" as the case may be.
+
+A robotic leg is moved by an actuator, which is a type of motor for moving or controlling a mechanism or system.  It is operated by a source of energy, usually in the form of an electric current, hydraulic fluid pressure or pneumatic pressure, and converts that energy into some kind of motion.
+
+A prosthetic leg, a prosthesis, is an artificial leg that is used to replace one that has been lost.

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+
+
+Memphis is a city along the Mississippi River in southwestern Shelby County, Tennessee, United States. The 2019 population was 651,073,[3] making Memphis the largest city on the Mississippi River[6] and the second-most populous in Tennessee, as well as the 26th-largest city in the United States. Greater Memphis is the 42nd-largest metropolitan area in the United States, with a population of 1,348,260 in 2017.[7] The city is the anchor of West Tennessee and the greater Mid-South region, which includes portions of neighboring Arkansas, Mississippi, and the Missouri Bootheel. Memphis is the seat of Shelby County, Tennessee's most populous county. One of the more historic and culturally significant cities of the southern United States, Memphis has a wide variety of landscapes and distinct neighborhoods.
+
+The first European explorer to visit the area of present-day Memphis was Spanish conquistador Hernando de Soto in 1541 with his expedition into the New World. The high Chickasaw Bluffs protecting the location from the waters of the Mississippi was then contested by the Spanish, French, and the English as Memphis took shape. Modern Memphis was founded in 1819 by three prominent Americans: John Overton, James Winchester, and future president Andrew Jackson.[8]
+
+Memphis grew into one of the largest cities of the Antebellum South as a market for agricultural goods, natural resources like lumber, and the American slave trade. After the American Civil War and the end of slavery, the city experienced even faster growth into the 20th century as it became among the largest world markets for cotton[9] and lumber.
+
+Home to Tennessee's largest African-American population, Memphis played a prominent role in the American civil rights movement and was the site of Martin Luther King Jr.'s 1968 assassination. The city now hosts the National Civil Rights Museum—a Smithsonian affiliate institution. Since the civil rights era, Memphis has become one of the nation's leading commercial centers in transportation and logistics.[10] Its largest employer is the multinational courier corporation FedEx, which maintains its global air hub at Memphis International Airport, making it the second-busiest cargo airport in the world. In addition to being a global air cargo leader, the International Port of Memphis also hosts the fifth-busiest inland water port in the U.S., with access to the Mississippi River[11] allowing shipments to arrive from around the world for conversion to train and trucking transport throughout the United States, making Memphis a multi-modal hub for trading goods for imports and exports despite its inland location.
+
+Memphis is a regional center for commerce, education, media, art, and entertainment. It has long had a prominent music scene,[12] with historic blues clubs on Beale Street originating the unique Memphis blues sound in the early 20th century. The city's music has continued to be shaped by a multicultural mix of influences: the blues, country, rock and roll, soul, and hip-hop. Memphis-style barbecue has achieved international prominence, and the city hosts the World Championship Barbecue Cooking Contest, which attracts over 100,000 visitors to the city annually.
+
+Occupying a substantial bluff rising from the Mississippi River, the site of Memphis has been a natural location for human settlement by varying cultures over thousands of years.[13] The area was settled in the first millennium A.D. by people of the Mississippian Culture, who had a network of communities throughout the Mississippi River Valley and its tributaries. They built complexes with large earthwork ceremonial and burial mounds as expressions of their sophisticated culture.[14] The historic Chickasaw Indian tribe, believed to be their descendants, later inhabited the site.[15]
+
+French explorers led by René-Robert Cavelier, Sieur de La Salle[16] and Spanish explorer Hernando de Soto[17][18] encountered the Chickasaw in that area in the 16th century.
+
+J. D. L. Holmes, writing in Hudson's Four Centuries of Southern Indians (2007), notes that this site was a third strategic point in the late 18th century through which European powers could control United States encroachment and their interference with Indian matters—after Fort Nogales (present-day Vicksburg) and Fort Confederación (present day Epes, Alabama): "Chickasaw Bluffs, located on the Mississippi River at the present-day location of Memphis. Spain and the United States vied for control of this site, which was a favorite of the Chickasaws."[19]:71
+
+In 1795 the Spanish Governor-General of Louisiana, Francisco Luis Héctor de Carondelet, sent his lieutenant governor, Manuel Gayoso de Lemos, to negotiate and secure consent from the local Chickasaw so that a Spanish fort could be erected on the bluff; Fort San Fernando De Las Barrancas was the result.[19]:71[20] Holmes notes that consent was reached despite opposition from "disappointed Americans and a pro-American faction of the Chickasaws" when the "pro-Spanish faction signed the Chickasaw Bluffs Cession and Spain provided the Chickasaws with a trading post".[19]:71
+
+Fort San Fernando de las Barrancas remained a focal point of Spanish activity until, as Holmes summarizes:
+
+[T]he Treaty of San Lorenzo or Pinckney's Treaty of 1795 [implemented in March 1797], [had as its result that] all of the careful, diplomatic work by Spanish officials in Louisiana and West Florida, which has succeeded for a decade in controlling the Indians [e.g., the Choctaws], was undone. The United States gained the right to navigate the Mississippi River and won control over the Yazoo Strip north of the thirty-first parallel.[19]:75,71
+
+The Spanish dismantled the fort, shipping its lumber and iron to their locations in Arkansas.[21]
+
+In 1796, the site became the westernmost point of the newly admitted state of Tennessee, in what was then called the Southwest United States. The area was still largely occupied and controlled by the Chickasaw nation. Captain Isaac Guion led an American force down the Ohio River to claim the land, arriving on July 20, 1797. By this time, the Spanish had departed.[22] The fort's ruins went unnoticed 20 years later when Memphis was laid out as a city, after the United States government paid the Chickasaw for land.[23]
+
+The city of Memphis was founded on May 22, 1819 (incorporated December 19, 1826), by John Overton, James Winchester and Andrew Jackson.[24][25] They named it after the ancient capital of Egypt on the Nile River.[26] Memphis developed as a trade and transportation center in the 19th century because of its flood-free location high above the Mississippi River. Located in the low-lying delta region along the river, its outlying areas were developed as cotton plantations, and the city became a major cotton market and brokerage center.
+
+The cotton economy of the antebellum South depended on the forced labor of large numbers of African-American slaves, and Memphis also developed as a major slave market for the domestic slave trade. Through the early 19th century, one million slaves were transported from the Upper South, in a huge forced migration to newly developed plantation areas in the Deep South. Many were transported by steamboats along the Ohio and Mississippi rivers. In 1857, the Memphis and Charleston Railroad was completed, connecting Memphis to the Atlantic coast of South Carolina; it was the only east-west railroad constructed across the southern states before the Civil War. This gave planters and cotton brokers access to the coast for shipping cotton to England, a major market.
+
+The city's demographics changed dramatically in the 1850s and 1860s under waves of immigration and domestic migration. Due to increased immigration since the 1840s and the Great Famine, ethnic Irish made up 9.9% of the population in 1850, but 23.2% in 1860, when the total population was 22,623.[27][28][29] They encountered considerable discrimination in the city but by 1860, the Irish constituted most of the police force. They also gained many elected and patronage positions in the Democratic Party city government, and an Irishman was elected mayor before the Civil War. At that time, representatives were elected to the city council from 30 wards. The elite were worried about corruption in this system and that so many saloonkeepers were active in the wards. German immigrants also made this city a destination after the 1848 revolutions; both the Irish and German immigrants were mostly Catholic, adding another element to demographic change in this formerly Protestant city.
+
+Tennessee seceded from the Union in June 1861, and Memphis briefly became a Confederate stronghold. Union ironclad gunboats captured it in the naval Battle of Memphis on June 6, 1862, and the city and state were occupied by the Union Army for the duration of the war. Union Army commanders allowed the city to maintain its civil government during most of this period but excluded Confederate veterans from office, which shifted political dynamics in the city as the war went on.[30] As Memphis was used as a Union supply base, associated with nearby Fort Pickering, it continued to prosper economically throughout the war. Meanwhile, Confederate General Nathan Bedford Forrest harassed Union forces in the area.
+
+The war years contributed to additional dramatic changes in city population. The Union Army's presence attracted many fugitive slaves who had escaped from surrounding rural plantations. So many sought protection behind Union lines that the Army set up contraband camps to accommodate them. Memphis's black population increased from 3,000 in 1860, when the total population was 22,623, to nearly 20,000 in 1865, with most settling south of the city limits.[31] The white population was also increasing, but not to the same degree. After race riots against the blacks in 1866, thousands left the city. The total population in 1870 was 40,220; the number of blacks declined to 15,000 that year, 37.4% of the total.
+
+The rapid demographic changes added to the stress of war and occupation and uncertainty about who was in charge, increasing tensions between the Irish policemen and black Union soldiers after the war.[30] In three days of rioting in early May 1866, the Memphis Riots erupted, in which white mobs made up of policemen, firemen, and other mostly ethnic Irish Americans attacked and killed 46 blacks, wounding 75 and injuring 100; raped several women; and destroyed nearly 100 houses while severely damaging churches and schools in South Memphis. Much of the black settlement was left in ruins. Two whites were killed in the riot.[31] Many blacks permanently fled Memphis afterward, especially as the Freedmen's Bureau continued to have difficulty in protecting them. Their population fell to about 15,000 by 1870,[30] 37.4% of the total population of 40,226.
+
+Historian Barrington Walker suggests that the Irish rioted against blacks because of their relatively recent arrival as immigrants and the uncertain nature of their own claim to "whiteness"; they were trying to separate themselves from blacks in the underclass. The main fighting participants were ethnic Irish, decommissioned black Union soldiers, and newly emancipated African American freedmen. Walker suggests that most of the mob were not in direct economic conflict with the blacks, as by then the Irish had attained better jobs, but were establishing dominance over the freedmen.[29]
+
+In Memphis, unlike disturbances in some other cities, ex-Confederate veterans were generally not part of the attacks against blacks. The outrages of the riots in Memphis and a similar one in New Orleans in September (the latter did include Confederate veterans) resulted in Congress's passing the Reconstruction Act and the Fourteenth Amendment to the U.S. Constitution.[31]
+
+In the 1870s, a series of yellow fever epidemics devastated Memphis, with the disease carried by river passengers along the waterways. During the Yellow Fever Epidemic of 1878, more than 5,000 people were listed in the official register of deaths between July 26 and November 27. The vast majority died of yellow fever, making the epidemic in the city of 40,000 one of the most traumatic and severe in urban U.S. history. Within four days of the Memphis Board of Health's declaration of a yellow fever outbreak, 20,000 residents fled the city. The ensuing panic left the poverty-stricken, the working classes, and the African-American community at most risk from the epidemic. Those who remained relied on volunteers from religious and physician organizations to tend to the sick. By the end of the year, more than 5,000 were confirmed dead in Memphis. The New Orleans health board listed "not less than 4,600" dead. The Mississippi Valley recorded 120,000 cases of yellow fever, with 20,000 deaths. The $15 million in losses caused by the epidemic bankrupted Memphis, and as a result its charter was revoked by the state legislature.
+
+By 1870, Memphis's population of 40,000 was almost double that of Nashville and Atlanta, and it was the second-largest city in the South after New Orleans.[32] Its population continued to grow after 1870, even when the Panic of 1873 hit the US hard, particularly in the South. The Panic of 1873 resulted in expanding Memphis's underclasses amid the poverty and hardship it wrought, giving further credence to Memphis as a rough, shiftless city. Leading up to the outbreak in 1878, it had suffered two yellow fever epidemics, cholera, and malaria, giving it a reputation as sickly and filthy. It was unheard of for a city with a population as large as Memphis's not to have any waterworks; the city still relied for supplies entirely on collecting water from the river and rain cisterns, and had no way to remove sewage.[32] The combination of a swelling population, especially of lower and working classes, and abysmal health and sanitary conditions made Memphis ripe for a serious epidemic.
+
+Kate Bionda, an owner of an Italian "snack house", died of the fever on August 13.[32] Hers was officially reported by the Board of Health, on August 14, as the first case of yellow fever in the city.[32] A massive panic ensued. The same trains and steamboats that brought thousands into Memphis now in five days carried away over 25,000 Memphians, more than half of the population.[32] On August 23, the Board of Health finally declared a yellow fever epidemic in Memphis, and the city collapsed, hemorrhaging its population. In July of that year, the city had a population of 47,000; by September, 19,000 remained and 17,000 of them had yellow fever.[32] The only people left in the city were the lower classes, such as German and Irish immigrant workers and African Americans. None had the means to flee the city, as did the middle and upper class whites of Memphis, and thus they were subjected to a city of death.
+
+Immediately following the Board of Health's declaration, a Citizen's Relief Committee was formed by Charles G. Fisher. It organized the city into refugee camps. The committee's main priority was to separate the poor from the city and isolate them in refugee camps.[32] The Howard Association, formed specifically for yellow fever epidemics in New Orleans and Memphis, organized nurses and doctors in Memphis and throughout the country.[33] They stayed at the Peabody Hotel, the only hotel to keep its doors open during the epidemic. From there they were assigned to their respective districts. Physicians of the epidemic reported seeing as many as 100 to 150 patients daily.[32]
+
+The sisters of St. Mary's Hospital played an important role during the epidemic in caring for the lower classes. Already supporting a girls' school and church orphanage, the sisters of St. Mary's also sought to provide care for the Canfield Asylum, a home for black children. Each day, they alternated caring for the orphans at St. Mary's, delivering children to the Canfield Asylum, and taking soup and medicine on house calls to patients.[32] Between September 9 and October 4, Sister Constance and three other nuns fell victim to the epidemic and died. They later became known as the Martyrs of Memphis.[34]
+
+At long last, on October 28, a killing frost struck. The city sent out word to Memphians scattered all over the country to come home. Though yellow fever cases were recorded in the pages of Elmwood Cemetery's burial record as late as February 29, 1874, the epidemic seemed quieted.[32] The Board of Health declared the epidemic, which caused over 20,000 deaths and financial losses of nearly $200 million, at an end.[35] On November 27, a general citizen's meeting was called at the Greenlaw Opera House to offer thanks to those who had stayed behind to serve, of whom many died. Over the next year property tax revenues collapsed, and the city could not make payments on its municipal debts. As a result, Memphis temporarily lost its city charter and was reclassified by the state legislature as a Taxing District from 1878 to 1893.[33] But a new era of sanitation was developed in the city, a new municipal government in 1879 helped form the first regional health organization, and during the 1880s Memphis led the nation in sanitary reform and improvements.[35]
+
+Perhaps the most significant effect of the yellow fever on Memphis was in demographic changes. Nearly all of Memphis's upper and middle classes vanished, depriving the city of its general leadership and class structure that dictated everyday life, similar to other large Southern cities such as New Orleans, Charleston, and Atlanta. In Memphis, the poorer whites and blacks fundamentally made up the city and played the greatest role in rebuilding it. The epidemic had resulted in Memphis being a less cosmopolitan place, with an economy that served the cotton trade and a population drawn increasingly from poor white and black Southerners.[36]
+
+The 1890 election was strongly contested, resulting in opponents of the D. P. Hadden faction working to deprive them of votes by disenfranchising blacks. The state had enacted several laws, including the requirement of poll taxes, that served to disenfranchise many blacks. Although political party factions in the future sometimes paid poll taxes to enable blacks to vote, African Americans lost their last positions on the city council in this election and were forced out of the police force. (They did not recover the ability to exercise the franchise until after passage of civil rights legislation in the mid-1960s.) Historian L. B. Wrenn suggests the heightened political hostility of the Democratic contest and related social tensions contributed to a white mob lynching three black grocers in Memphis in 1892.[37]:124,131
+
+Journalist Ida B. Wells of Memphis investigated the lynchings, as one of the men killed was a friend of hers. She demonstrated that these and other lynchings were more often due to economic and social competition than any criminal offenses by black men. Her findings were considered so controversial and aroused so much anger that she was forced to move away from the city. But she continued to investigate and publish the abuses of lynching.[37]:131
+
+Businessmen were eager to increase city population after the losses of 1878–79, and supported annexation of new areas to the city; this was passed in 1890 before the census. The annexation measure was finally approved by the state legislature through a compromise achieved with real estate magnates, and the area annexed was slightly smaller than first proposed.[37]:126
+
+In 1893 the city was rechartered with home rule, which restored its ability to enact taxes. The state legislature established a cap rate.[38] Although commission government was retained and enlarged to five commissioners, Democratic politicians regained control from the business elite. The commission form of government was believed effective in getting things done, but because all positions were elected at-large, requiring them to gain majority votes, this practice reduced representation by candidates representing significant minority political interests.[37]:126f
+
+In terms of its economy, Memphis developed as the world's largest spot cotton market and the world's largest hardwood lumber market, both commodity products of the Mississippi Delta. Into the 1950s, it was the world's largest mule market.[39] Attracting workers from rural areas as well as new immigrants, from 1900 to 1950 the city increased nearly fourfold in population, from 102,350 to 396,000 residents.[40]
+
+From the 1910s to the 1950s, Memphis was a place of machine politics under the direction of E. H. "Boss" Crump. He gained a state law in 1911 to establish a small commission to manage the city. The city retained a form of commission government until 1967 and patronage flourished under Crump. Per the publisher's summary of L.B. Wrenn's study of the period, "This centralization of political power in a small commission aided the efficient transaction of municipal business, but the public policies that resulted from it tended to benefit upper-class Memphians while neglecting the less affluent residents and neighborhoods."[37][page needed][41] The city installed a revolutionary sewer system and upgraded sanitation and drainage to prevent another epidemic. Pure water from an artesian well was discovered in the 1880s, securing the city's water supply. The commissioners developed an extensive network of parks and public works as part of the national City Beautiful movement, but did not encourage heavy industry, which might have provided substantial employment for the working-class population. The lack of representation in city government resulted in the poor and minorities being underrepresented. The majority controlled the election of all the at-large positions.[37][page needed]
+
+Memphis did not become a home rule city until 1963, although the state legislature had amended the constitution in 1953 to provide home rule for cities and counties. Before that, the city had to get state bills approved in order to change its charter and for other policies and programs. Since 1963, it can change the charter by popular approval of the electorate.[37]:194
+
+During the 1960s, the city was at the center of the Civil Rights Movement, as its large African-American population had been affected by state segregation practices and disenfranchisement in the early 20th century. African-American residents drew from the civil rights movement to improve their lives. In 1968, the Memphis sanitation strike began for living wages and better working conditions; the workers were overwhelmingly African American. They marched to gain public awareness and support for their plight: the danger of their work, and the struggles to support families with their low pay. Their drive for better pay had been met with resistance by the city government.
+
+Rev. Martin Luther King, Jr. of the Southern Christian Leadership Conference, known for his leadership in the non-violent movement, came to lend his support to the workers' cause. King stayed at the Lorraine Motel in the city, and was assassinated by a sniper on April 4, 1968, the day after giving his prophetic I've Been to the Mountaintop speech at the Mason Temple.
+
+Grief-stricken and enraged after learning of King's murder, many African Americans in the city rioted, looting and destroying businesses and other facilities, some by arson. The governor ordered Tennessee National Guardsmen into the city within hours, where small, roving bands of rioters continued to be active.[42] Fearing the violence, more of the middle-class began to leave the city for the suburbs.
+
+In 1970, the Census Bureau reported Memphis's population as 60.8% white and 38.9% black.[43] Suburbanization was attracting wealthier residents to newer housing outside the city. After the riots and court-ordered busing in 1973 to achieve desegregation of public schools, "about 40,000 of the system's 71,000 white students abandon[ed] the system in four years."[44] The city now has a majority-black population; the larger metropolitan area is narrowly majority white.
+
+Memphis is well known for its cultural contributions to the identity of the American South. Many renowned musicians grew up in and around Memphis and moved to Chicago and other areas from the Mississippi Delta, carrying their music with them to influence other cities and listeners over radio airwaves.[45] These included musicians such as Elvis Presley, Jerry Lee Lewis, Muddy Waters, Carl Perkins, Johnny Cash, Robert Johnson, W. C. Handy, B.B. King, Howlin' Wolf, Isaac Hayes, Booker T. Jones, Eric Gales, Al Green, Alex Chilton, Justin Timberlake, Three 6 Mafia, the Sylvers, Jay Reatard, Zach Myers, Aretha Franklin, and many others.
+
+According to the United States Census Bureau, the city has a total area of 324.0 square miles (839.2 km2), of which 315.1 square miles (816.0 km2) is land and 9.0 square miles (23.2 km2), or 2.76%, is water.[46]
+
+Downtown Memphis rises from a bluff along the Mississippi River. The city and metro area spread out through suburbanization, and encompass southwest Tennessee, northern Mississippi and eastern Arkansas. Several large parks were founded in the city in the early 20th century, notably Overton Park in Midtown and the 4,500-acre (18 km2) Shelby Farms. The city is a national transportation hub and Mississippi River crossing for Interstate 40, (east-west), Interstate 55 (north-south), barge traffic, Memphis International Airport (FedEx's "SuperHub" facility) and numerous freight railroads that serve the city.
+
+In both 2011 and 2012, the magazine Travel + Leisure ranked Memphis among the top ten "America's Dirtiest City", for widespread visibly littered public spaces, with unremoved trash, based on surveys by both readership and local citizens.[47]
+
+On a more positive note, in 2013 Forbes magazine ranked Memphis as one of the top 15 cities in the United States with an "emerging downtown" area.[48]
+
+The Memphis Riverfront stretches along the Mississippi River from the Meeman-Shelby Forest State Park in the north, to the T. O. Fuller State Park in the south. The River Walk is a park system that connects downtown Memphis from Mississippi River Greenbelt Park in the north, to Tom Lee Park  in the south.
+
+In recent years the City has decided to de-annex some of its territory.  Its is currently going through a 3 phase process to de-annex 5 areas within the city limits which will return to being part of unincorporated Shelby County.[49]  The first phase of de-annexation occurred on 1 January 2020 when the Eads area and River Bottoms areas of the city returned to county jurisdiction.  As a result Shelby County Sheriff are responsible for patrolling these former parts of the city of Memphis.[50]  It is estimated that this first phase of the de-annexation process will reduce the size of city by 5%, with a reduction in the city population by 0.03%.[49]   The following 2 phases will have a much more significant impact.
+
+Shelby County is located over four natural aquifers, one of which is recognized as the "Memphis Sand Aquifer" or simply as the "Memphis Aquifer". Located 350 to 1,100 feet (110 to 340 m) underground, this artesian water source is considered soft and estimated by Memphis Light, Gas and Water to contain more than 100 trillion US gallons (380 km3) of water.[51]
+
+Memphis has a humid subtropical climate (Köppen Cfa, Trewartha Cf), with four distinct seasons, and is located in USDA Plant Hardiness Zone 8a in downtown, cooling to 7b for much of the surrounding region.[52] Winter weather comes alternately from the upper Great Plains and the Gulf of Mexico, which can lead to drastic swings in temperature. Summer weather may come from Texas (very hot and humid) or the Gulf (hot and very humid). July has a daily average temperature of 82.7 °F (28.2 °C), with high levels of humidity due to moisture encroaching from the Gulf of Mexico. Afternoon and evening thunderstorms are frequent during summer, but usually brief, lasting no longer than an hour. Early autumn is pleasantly drier and mild, but can be hot until late October. Late autumn is rainy and cooler; precipitation peaks again in November and December. Winters are mild to chilly, with a January daily average temperature of 41.2 °F (5.1 °C). Snow occurs sporadically in winter, with an average seasonal snowfall of 3.9 inches (9.9 cm). Ice storms and freezing rain pose greater danger, as they can often pull tree limbs down on power lines and make driving hazardous. Severe thunderstorms can occur at any time of the year though mainly during the spring months. Large hail, strong winds, flooding and frequent lightning can accompany these storms. Some storms spawn tornadoes.
+
+The lowest temperature ever recorded in Memphis was −13 °F (−25 °C) on December 24, 1963,[53] and the highest temperature ever was 108 °F (42 °C) on July 13, 1980.[54] Over the course of a year, there is an average of 4.4 days of highs below freezing, 6.9 nights of lows below 20 °F (−7 °C), 43 nights of lows below freezing, 64 days of highs above 90 °F (32 °C)+, and 2.1 days of highs above 100 °F (38 °C)+.
+
+Annual precipitation is high (53.68 inches (1,360 mm)) and is relatively evenly distributed throughout the year, though the period August through October tends to be drier. Average monthly rainfall is especially high in March through May, November and December.
+
+For historical population data, see: History of Memphis, Tennessee. According to the 2006–2008 American Community Survey, the racial composition of the city of Memphis was:
+
+As of the 2010 United States Census[update], there were 652,078 people and 245,836 households in the city.[66] The population density was 2,327.4 people per sq mi (898.6/km2). There were 271,552 housing units at an average density of 972.2 per sq mi (375.4/km2). The racial makeup of the city was 63.33% African American, 29.39% White, 1.46% Asian American, 1.57% Native American, 0.04% Pacific Islander, 1.45% from other races, and 1.04% from two or more races. Hispanic or Latino of any race were 6.49% of the population.
+
+The median income for a household in the city was $32,285, and the median income for a family was $37,767. Males had a median income of $31,236 versus $25,183 for females. The per capita income for the city was $17,838. About 17.2% of families and 20.6% of the population were below the poverty line, including 30.1% of those under age 18, and 15.4% of those age 65 or over. In 2011, the U.S. Census Bureau ranked the Memphis area as the poorest large metro area in the country.[67] Dr. Jeff Wallace of the University of Memphis noted that the problem was related to decades of segregation in government and schools. He said that it was a low-cost job market, but other places in the world could offer cheaper labor, and the workforce was undereducated for today's challenges.[67]
+
+The Memphis Metropolitan Statistical Area (MSA), the 42nd largest in the United States, has a 2010 population of 1,316,100 and includes the Tennessee counties of Shelby, Tipton and Fayette; as well as the northern Mississippi counties of DeSoto, Marshall, Tate, and Tunica; and Crittenden County, Arkansas, all part of the Mississippi Delta.
+
+The total metropolitan area has a higher proportion of whites and a higher per capita income than the population in the city. The 2010 census shows that the Memphis metro area is close to a majority-minority population:
+
+the white population is 47.9 percent of the eight-county area's 1,316,100 residents. The non-Hispanic white population, a designation frequently used in census reports, was 46.2 percent of the total. The African American percentage was 45.7. For several decades, the Memphis metro area has had the highest percentage of black population among the nation's large metropolitan areas. The area has seemed on a path to become the nation's first metro area of one million or more with a majority black population.[68]
+
+In a reverse trend of the Great Migration, numerous African Americans and other minorities have moved into DeSoto County, and blacks have followed suburban trends, moving into the suburbs of Shelby County.[68]
+
+An 1870 map of Memphis shows religious buildings of the Baptist, Catholic, Episcopal, Methodist, Presbyterian, Congregational, and other Christian denominations, and a Jewish congregation.[69] In 2009, places of worship exist for Christians, Jews, Hindus, Buddhists, and Muslims.
+
+The international headquarters of the Church of God in Christ, the largest Pentecostal denomination in the United States, is located in Memphis. Its Mason Temple was named after the denomination's founder, Charles Harrison Mason. This auditorium is where Rev. Martin Luther King, Jr. gave his noted "I've Been to the Mountaintop" speech in April 1968, the night before he was assassinated at his motel. The National Civil Rights Museum, located in Memphis at the Lorraine Motel and other buildings, has an annual ceremony at Mason's Temple of Deliverance where it honors persons with Freedom Awards.
+
+Bellevue Baptist Church is a Southern Baptist megachurch in Memphis that was founded in 1903. Its current membership is around 30,000.[70] For many years, it was led by Adrian Rogers, a three-term president of the Southern Baptist Convention.
+
+Other notable and/or large churches in Memphis include Second Presbyterian Church (EPC), Highpoint Church[71] (SBC), Hope Presbyterian Church (EPC), Evergreen Presbyterian Church (PCUSA), Colonial Park United Methodist Church, Christ United Methodist Church, Idlewild Presbyterian Church (PCUSA), GraceLife Pentecostal Church (UPCI), First Baptist Broad, Temple of Deliverance, Calvary Episcopal Church, the Church of the River (First Unitarian Church of Memphis), and Annunciation Greek Orthodox Church.
+
+Memphis is home to two cathedrals. The Cathedral of the Immaculate Conception is the seat of the Roman Catholic Diocese of Memphis, and St. Mary's Episcopal Cathedral is the seat of the Episcopal Diocese of West Tennessee.
+
+Memphis is home to Temple Israel, a Reform synagogue that has approximately 7,000 members, making it one of the largest Reform synagogues in the country. Baron Hirsch Synagogue is the largest Orthodox shul in the United States.[72] Jewish residents were part of the city before the Civil War, but more Jewish immigrants came from Eastern Europe in the late 19th and early 20th centuries.
+
+Memphis is home to an estimated 10,000 to 15,000 Muslims of various cultures and ethnicities.[73]
+
+A number of seminaries are located in Memphis and the metropolitan area. Memphis is home to Memphis Theological Seminary and Harding School of Theology. Suburban Cordova is home to Mid-America Baptist Theological Seminary.
+
+In the 21st century, Memphis has struggled to reduce crime. In 2001, it ranked as the second-most dangerous city, and in 2002 as most dangerous by the Morgan Quitno rankings.[74] In 2004, violent crime in Memphis reached a decade record low. However, that trend changed and in 2005, Memphis was ranked the fourth-most dangerous city with a population of 500,000 or higher in the U.S.[75] Crime increased again in the first half of 2006. By 2014, Memphis crime had substantially decreased, bringing the city's ranking up to eleventh in violent crime.[76] Nationally, cities follow similar trends, and crime numbers tend to be cyclical. Nationally, other moderate-sized cities were also suffering large rises in crime, although crime in the largest cities continued to decrease or increased much less.[77][78][better source needed]
+
+In the first half of 2006, robbery of businesses increased 52.5%, robbery of individuals increased 28.5%, and homicides increased 18% over the same period of 2005. The Memphis Police Department responded with the initiation of Operation Blue C.R.U.S.H. (Crime Reduction Using Statistical History), which targets crime hotspots and repeat offenders.[79]
+
+Memphis ended 2005 with 154 murders, and 2006 ended with 160; in 2007 there were 164 murders, 2008 had 138, and 2009 had 132. Violent crimes dropped from 12,939 in 2008 to 12,047. Robbery dropped from 4,788 in 2008 to 4,137 in 2009. Aggravated assault dropped 53,870 in 2008 to 47,158 in 2009 (FBI's UCR). In 2006 and 2007, the Memphis metropolitan area ranked second-most dangerous in the nation among cities with a population over 500,000. In 2006, the Memphis metropolitan area ranked number one in violent crimes for major cities around the U.S., according to the FBI's annual crime rankings, whereas it had ranked second in 2005.[80]
+
+Since 2006, serious crime has dropped in Memphis. Between 2006 and 2008, the crime rate fell by 16%, while the first half of 2009 saw a reduction in serious crime of more than 10% from the previous year. The Memphis Police Department's use of the FBI National Incident-Based Reporting System, which is a more detailed method of reporting crimes than what is used in many other major cities, has been cited as a reason for Memphis's frequent appearance on lists of most dangerous U.S. cities.[81]
+With regard to homicide statistics released by the city in more recent years, they show another dramatic rise in murders committed in Memphis. There were 140 homicides in the city in 2014 and 161 the following year.[82][83]  Then, in 2016, police officials recorded 228 murders, a total that marked a 63% increase in homicides since 2014.[84]  According to Michael Rallings, the director of the Memphis Police Department, investigations determined that one third of the murder victims in 2016 had been involved in gang activity.[85]
+
+The city's central geographic location has been strategic to its business development. Located on the Mississippi River and intersected by five major freight railroads and two Interstate Highways, I-40 and I-55, Memphis is ideally located for commerce in the transportation and shipping industry. Its access by water was key to its initial development, with steamboats plying the Mississippi river. Railroad construction strengthened its connection to other markets to the east and west.
+
+Since the second half of the 20th century, highways and interstates have played major roles as transportation corridors. A third interstate, I-69, is under construction, and a fourth, I-22, has recently been designated from the former High Priority Corridor X. River barges are unloaded onto trucks and trains. The city is home to Memphis International Airport, the world's second busiest cargo airport (following Hong Kong). Memphis serves as a primary hub for FedEx Express shipping.
+
+As of 2014[update], Memphis was the home of three Fortune 500 companies: FedEx (no. 63), International Paper (no. 107), and AutoZone (no. 306).[86]
+
+Other major corporations based in Memphis include Allenberg Cotton, American Residential Services (also known as ARS/Rescue Rooter); Baker, Donelson, Bearman, Caldwell & Berkowitz; Cargill Cotton, City Gear, First Horizon National Corporation, Fred's, GTx, Lenny's Sub Shop, Mid-America Apartments, Perkins Restaurant and Bakery, ServiceMaster, True Temper Sports, Varsity Brands, and Verso Paper. Corporations with major operations based in Memphis include Gibson guitars (based in Nashville), and Smith & Nephew.
+
+The Federal Reserve Bank of St. Louis also has a branch in Memphis.
+
+The entertainment and film industries have discovered Memphis in recent years. Several major motion pictures, most of which were recruited and assisted by the Memphis & Shelby County Film and Television Commission,[87]  have been filmed in Memphis, including Making the Grade (1984), Elvis and Me (1988), Great Balls of Fire! (1988), Heart of Dixie (1989), Mystery Train (1989), The Silence of the Lambs (1991), Trespass (1991), The Gun in Betty Lou's Handbag (1992), The Firm (1993), The Delta (1996), The People Vs. Larry Flynt (1996), The Rainmaker (1997), Cast Away (2000), 21 Grams (2002), A Painted House (2002), Hustle & Flow (2005), Forty Shades of Blue (2005), Walk the Line (2005), Black Snake Moan (2007), Nothing But the Truth (2008), Soul Men (2008), and The Grace Card (2011). The Blind Side (2009) was set in Memphis but filmed in Atlanta. The 1992 television movie Memphis, starring Memphis native Cybill Shepherd, who also served as executive producer and writer, was also filmed in Memphis.
+
+One of the largest celebrations of the city is Memphis in May. The month-long series of events promotes Memphis's heritage and outreach of its people far beyond the city's borders. The four main events are the Beale Street Music Festival, International Week, The World Championship Barbecue Cooking Contest, and the Great River Run. The World Championship Barbecue Cooking Contest is the largest pork barbecue-cooking contest in the world.
+
+In April, downtown Memphis celebrates "Africa in April Cultural Awareness Festival", or simply Africa in April. The festival was designed to celebrate the arts, history, culture, and diversity of the African diaspora. Africa in April is a three-day festival with vendors' markets, fashion showcases, blues showcases, and an international diversity parade.[88]
+
+During late May-early June, Memphis is home to the Memphis Italian Festival at Marquette Park. The 2019 festival will be its 30th and has hosted musical acts, local artisans, and Italian cooking competitions. It also presents chef demonstrations, the Coors Light Competitive Bocce Tournament, the Galtelli Cup Recreational Bocce Tournament, a volleyball tournament, and pizza tossing demonstrations. This festival was started by Holy Rosary School and Parish and began inside the School parking lot in 1989. The Memphis Italian Festival is run almost completely by former and current Holy Rosary School and Church members and begins with a 5K run each year.
+
+Carnival Memphis, formerly known as the Memphis Cotton Carnival, is an annual series of parties and festivities in June that salutes various aspects of Memphis and its industries. An annual King and Queen of Carnival are secretly selected to reign over Carnival activities. From 1935 to 1982, the African-American community staged the Cotton Makers Jubilee; it has merged with Carnival Memphis.[89]
+
+A market and arts festival, the Cooper-Young Festival,[90] is held annually in September in the Cooper-Young district of Midtown Memphis. The event draws artists from all over North America and includes local music, art sales, contests, and displays.
+
+Memphis sponsors several film festivals: the Indie Memphis Film Festival, Outflix, and the Memphis International Film and Music Festival. The Indie Memphis Film Festival is in its 14th year and was held April 27–28, 2013.[91] Recognized by MovieMaker Magazine as one of 25 "Coolest Film Festivals" (2009) and one of 25 "Festivals Worth the Entry Fee" (2011), Indie Memphis offers Memphis year-round independent film programming, including the Global Lens international film series, IM Student Shorts student films, and an outdoor concert film series at the historic Levitt Shell. The Outflix Film Festival, also in its 15th year, was held September 7–13, 2013. Outflix features a full week of LGBT cinema, including short films, features, and documentaries. The Memphis International Film and Music Festival is held in April; it is in its 11th year and takes place at Malco's Ridgeway Four.
+
+On the weekend before Thanksgiving, the Memphis International Jazz Festival is held in the South Main Historic Arts District in Downtown Memphis. This festival promotes the important role Memphis has played in shaping Jazz nationally and internationally. Acts such as George Coleman, Herman Green, Kirk Whalum and Marvin Stamm all come out of the rich musical heritage in Memphis.
+
+Formerly titled the W. C. Handy Awards, the International Blues Awards are presented by the Blues Foundation (headquartered in Memphis) for Blues music achievement. Weeklong playing competitions are held, as well as an awards banquet including a night of performance and celebration.
+
+Memphis is the home of founders and pioneers of various American music genres, including Memphis soul, Memphis blues, gospel, rock n' roll, Memphis rap, Buck, crunk, and "sharecropper" country music (in contrast to the "rhinestone" country sound of Nashville).
+
+Many musicians, including Aretha Franklin, Jerry Lee Lewis, Johnny Cash, Elvis Presley, Carl Perkins, Roy Orbison, Booker T. & the M.G.'s, Otis Redding, Isaac Hayes, Shawn Lane, Al Green, Rance Allen, Percy Sledge, Solomon Burke, William Bell, Sam & Dave and B.B. King, got their start in Memphis in the 1950s and 1960s.
+
+Beale Street is a national historical landmark, and shows the impact Memphis has had on American blues, particularly after World War II as electric guitars took precedence. Sam Phillips' Sun Studio, the most seminal recording studio in American popular music, still stands, and is open for tours. Elvis, Johnny Cash, Jerry Lee Lewis, Carl Perkins and Roy Orbison all made their first recordings there, and were "discovered" by Phillips. Many great blues artists recorded there, such as W. C. Handy, Father of the Blues.
+
+Stax Records created a classic 1960s soul music sound, much grittier and horn-based than Motown. Booker T. and the M.G.s were the label's backing band for most of the classic hits that came out of Stax, by Sam and Dave, Otis Redding, Wilson Pickett, and many more. The sound still lives on in the Blues Brothers movie, in which many of the musicians starred as themselves.
+
+Memphis is noted for its influence on the power pop musical genre in the 1970s. Notable bands and musicians include Big Star, Chris Bell, Alex Chilton, Tommy Hoehn, The Scruffs, and Prix.[92][93]
+
+Several notable singers are from the Memphis area, including Justin Timberlake, K. Michelle, Kirk Whalum, Three 6 Mafia, Ruth Welting, Kid Memphis and Kallen Esperian. The Metropolitan Opera of New York had its first tour in Memphis in 1906; in the 1990s it decided to tour only larger cities. Metropolitan Opera performances are now broadcast in HD at local movie theaters across the country.
+
+In addition to the Brooks Museum and Dixon Gallery and Gardens, Memphis plays host to two burgeoning visual art areas, one city-sanctioned, and the other organically formed.
+
+The South Main Arts District is an arts neighborhood in south downtown. Over the past 20 years, the area has morphed from a derelict brothel and juke joint neighborhood to a gentrified, well-lit area sponsoring "Trolley Night", when arts patrons stroll down the street to see fire spinners, DJs playing in front of clubs, specialty shops and galleries.[94][95]
+
+Another developing arts district in Memphis is Broad Avenue. This east-west avenue is undergoing neighborhood revitalization from the influx of craft and visual artists taking up residence and studios in the area.[96][97] An art professor from Rhodes College holds small openings on the first floor of his home for local students and professional artists. Odessa, another art space on Broad Avenue, hosts student art shows and local electronic music. Other gallery spaces spring up for semi-annual artwalks.[98][99]
+
+Memphis also has non-commercial visual arts organizations and spaces, including local painter Pinkney Herbert's Marshall Arts gallery, on Marshall Avenue near Sun Studios, another arts neighborhood characterized by affordable rent.[100]
+
+Well-known writers from Memphis include Shelby Foote, the noted Civil War historian. Novelist John Grisham grew up in nearby DeSoto County, Mississippi, and sets many of his books in Memphis.
+
+Many works of fiction and literature are set in Memphis. These include The Reivers by William Faulkner (1962), September, September by Shelby Foote (1977); Peter Taylor's The Old Forest and Other Stories (1985), and his Pulitzer Prize-winning A Summons to Memphis (1986); The Firm (1991) and The Client (1993), both by John Grisham; Memphis Afternoons: a Memoir by James Conaway (1993), Plague of Dreamers by Steve Stern (1997); Cassina Gambrel Was Missing by William Watkins (1999); The Guardian by Beecher Smith (1999), "We are Billion-Year-Old Carbon" by Corey Mesler (2005), The Silence of the Lambs by Thomas Harris, and The Architect by James Williamson (2007).
+
+Other Memphis attractions include the Liberty Bowl Memorial Stadium, FedExForum, and Mississippi riverboat day cruises.
+
+Media related to Memphis, Tennessee at Wikimedia Commons
+
+Media related to Cemeteries in Memphis, Tennessee at Wikimedia Commons
+
+The Memphis National Cemetery is a United States National Cemetery located in northeastern Memphis.
+
+Historic Elmwood Cemetery is one of the oldest rural garden cemeteries in the South, and contains the Carlisle S. Page Arboretum. Memorial Park Cemetery is noted for its sculptures by Mexican artist Dionicio Rodriguez.
+
+Elvis Presley was originally buried in Forest Hill Cemetery, the resting place of his backing band's bassist, Bill Black. After an attempted grave robbing, his body was moved and reinterred at the grounds of Graceland.
+
+The Memphis Grizzlies of the National Basketball Association is the only team from one of the "big four" major sports leagues in Memphis.[107] The Memphis Redbirds of the Pacific Coast League is a Triple-A baseball farm team for the St. Louis Cardinals.[108]
+
+The University of Memphis college basketball team, the Memphis Tigers, has a strong following in the city due to a history of competitive success. The Tigers have competed in three NCAA Final Fours (1973, 1985, 2008), with the latter two appearances being vacated. The current coach of the Memphis Tigers is Anfernee Hardaway. Memphis is home to Liberty Bowl Memorial Stadium, the site of University of Memphis football, the Liberty Bowl and the Southern Heritage Classic.
+
+The annual St. Jude Classic, a regular part of the PGA Tour, is also held in the city. Each February the city hosts the Regions Morgan Keegan Championships and the Cellular South Cup, which are men's ATP World Tour 500 series and WTA events, respectively.
+
+Memphis has a significant history in pro wrestling. Jerry "The King" Lawler and Jimmy "The Mouth of the South" Hart are among the sport's most well-known figures who came out of the city. Sputnik Monroe, a wrestler of the 1950s, like Lawler, promoted racial integration in the city. Ric Flair also noted Memphis as his birthplace.
+
+In the 1970s and early 1980s, the former WFL franchise Memphis Southmen / Memphis Grizzlies sued the NFL in an attempt to be accepted as an expansion franchise. In 1993, the Memphis Hound Dogs was a proposed NFL expansion that was passed over in favor of the Jacksonville Jaguars and Carolina Panthers. The Liberty Bowl Memorial Stadium also served as the temporary home of the former Tennessee Oilers while the city of Nashville worked out stadium issues.
+
+The city is also the site of Memphis International Raceway, which held NASCAR events from 1998 to 2009, when Dover Motorsports closed it. In 2011 it reopened under different ownership. It no longer holds NASCAR races, but the Arca Menards Series returned to the track in 2020.
+
+Media related to Parks in Memphis, Tennessee at Wikimedia Commons
+Major Memphis parks include W.C. Handy Park, Tom Lee Park, Audubon Park, Overton Park including the Old Forest Arboretum,[109] the Lichterman Nature Center (a nature learning center), the Memphis Botanic Garden,[110] and Jesse H Turner Park.
+
+Shelby Farms park, located at the eastern edge of the city, is one of the largest urban parks in the United States.
+
+Beginning in 1963, Memphis adopted a mayor-council form of government, with 13 City Council members, six elected at-large from throughout the city and seven elected from geographic districts. Following passage of the Voting Rights Act of 1965, civil rights activists challenged the at-large is electoral system in court because it made it more difficult for the minority to elect candidates of their choice; at-large voting favored candidates who could command a majority across the city. In 1995, the city adopted a new plan. The 13 Council positions are elected from nine geographic districts: seven are single-member districts and two elect three members each.
+
+Jim Strickland is the city's current mayor, elected on October 8, 2015. He is a former Memphis city councilman. The previous mayor of the city of Memphis was A C Wharton.
+
+Since the late 20th century, regional discussions have recurred on the concept of consolidating unincorporated Shelby County and Memphis into a metropolitan government, as Nashville-Davidson County did in 1963. Consolidation was a referendum item on the 2010 ballots in both the city of Memphis and Shelby County, under the state law for dual-voting on such measures. The referendum was controversial in both jurisdictions. Black leaders, including then-Shelby County Commissioner Joe Ford and national civil rights leader Al Sharpton, opposed the consolidation. According to the plaintiffs' expert, Marcus Pohlmann, these leaders "tried to turn that referendum into a civil rights issue, suggesting that for blacks to vote for consolidation was to give up hard-won civil rights victories of the past".[111]
+
+In October 2010 before the vote, eight Shelby County citizens had filed a lawsuit in federal court against the state and the Shelby County Elections Commission against the dual-voting requirement. Plaintiffs argued that total votes for the referendum should have been counted together, rather than as separate elections. City voters narrowly supported the measure for consolidation with 50.8% in favor; county voters overwhelmingly voted against the measure with 85% against.[112] The state argued that with the election decided, the lawsuit should be dismissed, but the federal court disagreed.[111]
+
+By late 2013, in pre-trial actions, both sides were trying to disqualify the other's experts, in discussions of whether regional voting revealed racial polarization, and whether voting on the referendum demonstrated racial bloc voting. "The experts for both sides have clashed on whether racial bloc voting is inevitable in local elections and whether that would require some kind of court remedy."[111]
+
+The defendants' expert, Todd Donovan, did not think that polarized voting as revealed for political candidates meant that "African-American voters and white voters have polarized interests when it comes to referendum choices on government administration, taxation, service provision and other policy questions."[111] He noted, "In the absence of distinct political interests that create polarized blocs of referendum voters defined by race, there is no cohesive racial minority voting interest that can be diluted by a referendum."[111]
+
+In 2014, the federal district court dismissed the lawsuit, on the grounds that the referendum would have failed when both jurisdictions' votes were counted together. (In total voting, 64% of voters opposed the consolidation.) In the last week of December 2014, the U.S. Sixth District Court of Appeals upheld that decision, ruling that, ""In this election, the referendum for consolidation did not pass and would not have passed even if there had been no dual-majority vote requirement (with the vote counts combined)."[112]
+
+Before the referendum, the decision was made by the city and county to exclude public school management and operations from the proposed consolidation. As noted below, in 2011 the Memphis city council voted to dissolve its city school board and consolidate with the Shelby County School System, without the collaboration or agreement of Shelby County.[113] The city had authority for this action under Tennessee state laws that differentiate between city and county powers.
+
+The city is served by Shelby County Schools. On March 8, 2011, residents voted to dissolve the charter for Memphis City Schools, effectively merging it with the Shelby County School District.[114] After issues with state law and court challenges, the merger took effect the start of the 2013–14 school year. In Shelby County, six incorporated cities voted to establish separate school systems in 2013.
+
+The Shelby County School System operates more than 200 elementary, middle, and high schools.
+
+The Memphis area is also home to many private, college-prep schools: Briarcrest Christian School (co-ed), Christian Brothers High School (boys), Evangelical Christian School (co-ed), First Assembly Christian School (co-ed), St. Mary's Episcopal School (girls), Hutchison School (girls), Lausanne Collegiate School (co-ed), Memphis University School (boys), Saint Benedict at Auburndale (co-ed), St. Agnes Academy (girls), Immaculate Conception Cathedral School (girls), and Elliston Baptist Academy (co-ed). Also included in this list is Memphis Harding Academy, a co-ed school affiliated with the Churches of Christ.
+
+Colleges and universities located in the city include the University of Memphis, including University of Memphis Cecil C. Humphreys School of Law, Rhodes College, Christian Brothers University, Memphis College of Art, LeMoyne–Owen College, Baptist College of Health Sciences, Memphis Theological Seminary, Harding School of Theology, Embry–Riddle Aeronautical University, Worldwide (Memphis Campus),[115] Reformed Theological Seminary (satellite campus), William R. Moore College of Technology, Southern College of Optometry, Southwest Tennessee Community College, Tennessee Technology Center at Memphis, Visible Music College, Mid-America Baptist Theological Seminary, and the University of Tennessee Health Science Center. Memphis also has campuses of several for-profit post-secondary institutions, including Concorde Career College, ITT Technical Institute, Remington College,[116] Vatterott College,[117] and University of Phoenix.
+
+The University of Tennessee College of Dentistry was founded in 1878, making it the oldest dental college in the South, and the third oldest public college of dentistry in the United States.[118]
+
+The Christian Brothers High School Band is the oldest high school band in America, founded in 1872.[119]
+
+Examples of Colleges and Universities in Memphis, Tennessee
+
+Nielsen Media Research currently defines Memphis and its surrounding metropolitan area as the 51st largest American media market.[125]
+
+Major broadcast television affiliate stations in the Memphis area include, but are not limited to:
+
+Terrestrial broadcast radio stations in the Memphis area include, but are not limited to:
+
+Memphis is the subject of numerous pop and country songs, including "The Memphis Blues" by W. C. Handy, "Memphis, Tennessee" by Chuck Berry, "Night Train to Memphis" by Roy Acuff, "Goin' to Memphis" by Paul Revere and the Raiders, "Queen of Memphis" by Confederate Railroad, "Memphis Soul Stew" by King Curtis, "Maybe It Was Memphis" by Pam Tillis, "Graceland" by Paul Simon, "Memphis Train" by Rufus Thomas, "All the Way from Memphis" by Mott the Hoople, "Wrong Side of Memphis" by Trisha Yearwood, "Stuck Inside of Mobile with the Memphis Blues Again" by Bob Dylan, "Memphis Skyline" by Rufus Wainwright, "Sequestered in Memphis" by The Hold Steady and "Walking in Memphis" by Marc Cohn.
+
+In addition, Memphis is mentioned in scores of other songs, including "Proud Mary" by Creedence Clearwater Revival, "Honky Tonk Women" by the Rolling Stones, "Dixie Chicken" by Little Feat, "Who's Gonna Fill Their Shoes" by George Jones, "Daisy Jane" by America, "Life Is a Highway" by Tom Cochrane, "Black Velvet" by Alannah Myles, "Cities" by Talking Heads, "Crazed Country Rebel" by Hank Williams III, "Pride (In the Name of Love)" by U2, "M.E.M.P.H.I.S." by the Disco Biscuits, "New New Minglewood Blues" and "Candyman" by the Grateful Dead, "You Should Be Glad" by Widespread Panic, "Roll With Me" by 8Ball & MJG, "Someday" by Steve Earle and popularly recorded by Shawn Colvin, and many others.
+
+More than 1,000 commercial recordings of over 800 distinct songs contain "Memphis" in them. The Memphis Rock N' Soul Museum maintains an ever updated list of these on their website.[129]
+
+Many films are set in the American city including, Black Snake Moan, The Blind Side, Cast Away, Choices: The Movie, The Client, The Firm, Forty Shades of Blue, Great Balls of Fire!, Hustle & Flow, Kill Switch, Making the Grade, Memphis Belle, Mississippi Grind, Mystery Train, N-Secure, The Rainmaker, The Silence of the Lambs, Soul Men, and Walk the Line.
+
+Many of those and other films have also been filmed in Memphis including, Black Snake Moan, Walk the Line, Hustle & Flow, Forty Shades of Blue, 21 Grams, A Painted House, American Saint, The Poor and Hungry, Cast Away, Woman's Story, The Big Muddy, The Rainmaker, Finding Graceland, The People vs. Larry Flynt, The Delta, Teenage Tupelo, A Family Thing, Without Air, The Firm, The Client, The Gun in Betty Lou's Handbag, Trespass, The Silence of the Lambs, Great Balls of Fire!, Elvis and Me, Mystery Train, Leningrad Cowboys Go America, Heart of Dixie, The Contemporary Gladiator, U2: Rattle and Hum, Making the Grade, The River Rat, The River, Hallelujah!, Elizabethtown, 3000 Miles to Graceland, A Face in the Crowd, Undefeated, Man on the Moon, Nothing But the Truth, Sore Losers, Soul Men, I Was a Zombie for the F.B.I., I'm From Hollywood, The Grace Card, This is Elvis, Cookie's Fortune, Open Five, The Open Road, In the Valley of Elah, Walk Hard, My Blueberry Nights, Savage Country, and Two-Lane Blacktop.[130]
+
+The television series Greenleaf, Memphis Beat, Quarry and Bluff City Law are set in the city.
+
+Literature
+
+Many works of fiction and literature are set in Memphis. These include The Reivers by William Faulkner (1962), September, September by Shelby Foote (1977); Peter Taylor's The Old Forest and Other Stories (1985), and his Pulitzer Prize-winning A Summons to Memphis (1986); The Firm (1991) and The Client (1993), both by John Grisham; Memphis Afternoons: a Memoir by James Conaway (1993), Plague of Dreamers by Steve Stern (1997); Cassina Gambrel Was Missing by William Watkins (1999); The Guardian by Beecher Smith (1999), "We are Billion-Year-Old Carbon" by Corey Mesler (2005), The Silence of the Lambs by Thomas Harris, and The Architect by James Williamson (2007).
+
+Interstate 40, Interstate 55, Interstate 22, Interstate 240, Interstate 269, and State Route 385 are the main expressways in the Memphis area. Interstates 40 and 55 cross the Mississippi River at Memphis from the state of Arkansas.[131] Interstate 69 is a proposed interstate that, upon completion, would connect Memphis to Canada and Mexico.[132]
+
+I-40 is a coast-to-coast freeway that connects Memphis to Nashville and on to North Carolina to the east, and Little Rock, Arkansas, Oklahoma City, and the Greater Los Angeles Area to the west. I-55 connects Memphis to St. Louis and Chicago to the north, and Jackson, Mississippi and New Orleans to the south. I-240 is the inner beltway which serves areas including Downtown, Midtown, South Memphis, Memphis International Airport, East Memphis, and North Memphis.[131] I-269 is the larger, outer interstate loop immediately serving the suburbs of Millington, Eads, Arlington, Collierville, and Hernando, Mississippi. It was completed in 2018.[133]
+
+Interstate 22 connects Memphis with Birmingham, Alabama, via northern Mississippi (including Tupelo) and northwestern Alabama. While technically not entering the city of Memphis proper, I-22 ends at I-269 in Byhalia, Mississippi, connecting it to the rest of the Memphis interstate system.
+
+Interstate 69 is proposed to follow I-55 and I-240 through the city of Memphis. Once completed, I-69 will link Memphis with Port Huron, Michigan via Indianapolis, Indiana, and Brownsville, Texas via Shreveport, Louisiana and Houston, Texas.[132]
+
+A new spur, Interstate 555, also serves the Memphis metro area connecting it to Jonesboro, Arkansas.
+
+Other important federal highways though Memphis include the east-west U.S. Route 70, U.S. Route 64, and U.S. Route 72; and the north-south U.S. Route 51 and U.S. Route 61.[131] The former is the historic highway north to Chicago via Cairo, Illinois, while the latter roughly parallels the Mississippi River for most of its course and crosses the Mississippi Delta region to the south, with the Delta also legendary for Blues music.
+
+A large volume of railroad freight moves through Memphis, because of its two heavy-duty Mississippi River railroad crossings, which carry several major east-west railroad freight lines, and also because of the major north-south railroad lines through Memphis which connect with such major cities as Chicago, St. Louis, Indianapolis, Louisville, New Orleans, Dallas, Houston, Mobile, and Birmingham.
+
+By the early 20th century, Memphis had two major passenger railroad stations, which made the city a regional hub for trains coming from the north, east, south and west. After passenger railroad service declined heavily through the middle of the 20th century, the Memphis Union Station was demolished in 1969. The Memphis Central Station[134] was eventually renovated, and it still serves the city.  The only inter-city passenger railroad service to Memphis is the daily City of New Orleans train, operated by Amtrak, which has one train northbound and one train southbound each day between Chicago and New Orleans.
+
+Memphis International Airport is the global "SuperHub" of FedEx Express, and has the second largest cargo operations by volume of any airport worldwide, surpassed only by Hong Kong International Airport.[135][136]
+
+Memphis International ranks as the 41st busiest passenger airport in the US and served as a hub for Northwest Airlines (later Delta Air Lines) until September 3, 2013.[137] and had 4.39 million boarding passengers (enplanements) in 2011, an 11.9% decrease over the previous year.[138] Delta has reduced its flights at Memphis by approximately 65% since its 2008 merger with Northwest Airlines and operates an average of 30 daily flights as of December 2013, with two international destinations (Cancún - seasonally; Toronto year-round). Delta Air Lines announced the closing of its Memphis pilot and crew base in 2012. Other airlines providing passenger service are: Southwest Airlines; American Airlines; United Airlines; Allegiant; Frontier; Air Canada; and Southern Vacations Express.[139]
+
+There are also general aviation airports in the Memphis Metropolitan Area, including the Millington Regional Jetport, located at the former Naval Air Station in Millington, Tennessee.
+
+Memphis has the second-busiest cargo port on the Mississippi River, which is also the fourth-busiest inland port in the United States.[140] The International Port of Memphis covers both the Tennessee and Arkansas sides of the Mississippi River from river mile 725 (km 1167) to mile 740 (km 1191).[141] A focal point of the river port is the industrial park on President's Island, just south of Downtown Memphis.
+
+Four railroad and highway bridges cross the Mississippi River at Memphis. In order of their opening years, these are the Frisco Bridge (1892, single-track rail), the Harahan Bridge (1916, a road-rail bridge until 1949, currently carries double-track rail), the Memphis-Arkansas Memorial Bridge (Highway, 1949; later incorporated into Interstate 55), and the Hernando de Soto Bridge (Interstate 40, 1973). A bicycle/pedestrian walkway opened along the Harahan Bridge in late 2016, utilizing the former westbound roadway.[142][143][144]
+
+Memphis's primary utility provider is the Memphis Light, Gas and Water Division (MLGW). This is the largest three-service municipal utility in the United States, providing electricity, natural gas, and pure water service to all residents of Shelby County. Prior to that, Memphis was served by two primary electric companies, which were merged into the Memphis Power Company.[145]
+
+The City of Memphis bought the private company in 1939 to form MLGW,[145][146] which was an early customer of electricity from the Tennessee Valley Authority (TVA). In 1954 the Dixon-Yates contract was proposed to make more power available to the city from the TVA, but the contract was cancelled; it had been an issue for the Democrats in the 1954 Congressional elections.
+
+MLGW still buys most of its power from TVA, and the company pumps its own fresh water from the Memphis Aquifer, using more than 180 water wells.
+
+The Memphis and Shelby County region supports numerous hospitals, including the Methodist and Baptist Memorial health systems, two of the largest private hospitals in the country.
+
+Methodist Le Bonheur Healthcare, the largest healthcare provider in the Memphis region and the fourth largest employer as of 2018,[147] operates seven hospitals and several rural clinics. Modern Healthcare magazine ranked Methodist Healthcare[148] in the top 100 integrated healthcare networks in the United States. Methodist Healthcare operates, among others, the Le Bonheur Children's Hospital, which offers primary level 1 pediatric trauma care, as well as a nationally recognized pediatric brain tumor program.
+
+Baptist Memorial Healthcare operates fifteen hospitals (three in Memphis), including Baptist Memorial Hospital, and with a merger in 2018 became the largest healthcare system in the mid-South.[149] According to Health Care Market Guide's annual studies, Mid-Southerners have named Baptist Memorial their "preferred hospital choice for quality".
+
+The St. Jude Children's Research Hospital, leading pediatric treatment and research facility focused on children's catastrophic diseases, resides in Memphis. The institution was conceived and built by entertainer Danny Thomas in 1962 as a tribute to St. Jude Thaddeus, patron saint of impossible, hopeless, and difficult causes.
+
+Memphis is also home to Regional One Healthcare,[150] which is locally referred to as "The Med". In recent years, the hospital has experienced severe funding difficulties that nearly led to a reduction or elimination of emergency room services. In July 2010, The Med received approximately $40.6 million in federal and local funding to keep the Elvis Presley Trauma Center operational.
+
+Memphis is home to Delta Medical Center of Memphis,[151] which is the only employee-owned medical facility in North America.
+
+Individual health insurance marketplace insurers are limited, with Bright Health and Cigna offering coverage in the area.[152]
+
+Memphis has three sister cities, as per Sister Cities International:[153]

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+
+
+Menstruation, also known as a period or monthly,[1] is the regular discharge of blood and mucosal tissue (known as menses) from the inner lining of the uterus through the vagina.[2] The first period usually begins between twelve and fifteen years of age, a point in time known as menarche.[1] However, periods may occasionally start as young as eight years old and still be considered normal.[2] The average age of the first period is generally later in the developing world, and earlier in the developed world.[3] The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women, and 21 to 31 days in adults (an average of 28 days).[2][3] Bleeding usually lasts around 2 to 7 days.[2] Menstruation stops occurring after menopause, which usually occurs between 45 and 55 years of age.[4] Periods also stop during pregnancy and typically do not resume during the initial months of breastfeeding.[2]
+
+Up to 80% of women report having some symptoms prior to menstruation.[5] Common signs and symptoms include acne, tender breasts, bloating, feeling tired, irritability, and mood changes.[6] These may interfere with normal life, therefore qualifying as premenstrual syndrome, in 20 to 30% of women.[5] In 3 to 8%, symptoms are severe.[5]
+
+A lack of periods, known as amenorrhea, is when periods do not occur by age 15 or have not occurred in 90 days.[2] Other problems with the menstrual cycle include painful periods and abnormal bleeding such as bleeding between periods or heavy bleeding.[2] Menstruation in other animals occur in primates (apes and monkeys).[7][8]
+
+The menstrual cycle occurs due to the rise and fall of hormones.[2] This cycle results in the thickening of the lining of the uterus, and the growth of an egg, (which is required for pregnancy).[2] The egg is released from an ovary around day fourteen in the cycle; the thickened lining of the uterus provides nutrients to an embryo after implantation.[2] If implantation does not occur, the lining is released in what is known as menstruation.[2]
+
+The first menstrual period occurs after the onset of pubertal growth, and is called menarche. The average age of menarche is 12 to 15.[1][9] However, it may start as early as eight.[2] The average age of the first period is generally later in the developing world, and earlier in the developed world.[3] The average age of menarche has changed little in the United States since the 1950s.[3]
+
+Menstruation is the most visible phase of the menstrual cycle and its beginning is used as the marker between cycles. The first day of menstrual bleeding is the date used for the last menstrual period (LMP). The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women, and 21 to 31 days in adults.[2][3] The average length is 28 days; one study estimated it at 29.3 days.[10]
+
+Perimenopause is when fertility in a female declines, and menstruation occurs less regularly in the years leading up to the final menstrual period, when a female stops menstruating completely and is no longer fertile. The medical definition of menopause is one year without a period and typically occurs between 45 and 55 in Western countries.[4][11]:p. 381
+
+During pregnancy and for some time after childbirth, menstruation does not occur. The average length of postpartum amenorrhoea is longer when breastfeeding; this is termed lactational amenorrhoea.
+
+In most women, various physical changes are brought about by fluctuations in hormone levels during the menstrual cycle. This includes muscle contractions of the uterus (menstrual cramping) that can precede or accompany menstruation. Some may notice bloating, changes in sex drive, fatigue, breast tenderness, headaches, or irritability before the onset of their period.[12][13][14] It is unclear if the breast discomfort and bloating is related to electrolyte changes or water retention.[15] Some women have mild or no symptoms before the onset of their periods.[13] A healthy diet, reduced consumption of salt, caffeine and alcohol, and regular exercise may be effective for women in controlling water retention.[16] Severe symptoms that disrupt daily activities and functioning may be diagnosed as premenstrual dysphoric disorder.[13]
+
+Many women experience painful cramps, also known as dysmenorrhea, during menstruation.[17]
+
+Painful menstrual cramps that result from an excess of prostaglandin release are referred to as primary dysmenorrhea. Primary dysmenorrhea usually begins within a year or two of menarche, typically with the onset of ovulatory cycles.[18] Treatments that target the mechanism of pain include non-steroidal anti-inflammatory drugs (NSAIDs) and hormonal contraceptives. NSAIDs inhibit prostaglandin production. With long-term treatment, hormonal birth control reduces the amount of uterine fluid/tissue expelled from the uterus. Thus resulting in shorter, less painful menstruation.[19] These drugs are typically more effective than treatments that do not target the source of the pain (e.g. acetaminophen).[20] Risk factors for primary dysmenorrhea include: early age at menarche, long or heavy menstrual periods, smoking, and a family history of dysmenorrhea.[18] Regular physical activity may limit the severity of uterine cramps.[18]
+
+For many women, primary dysmenorrhea gradually subsides in late second generation. Pregnancy has also been demonstrated to lessen the severity of dysmenorrhea, when menstruation resumes.  However, dysmenorrhea can continue until menopause. 5–15% of women with dysmenorrhea experience symptoms severe enough to interfere with daily activities.[18]
+
+Secondary dysmenorrhea is the diagnosis given when menstruation pain is a secondary cause to another disorder. Conditions causing secondary dysmenorrhea include endometriosis, uterine fibroids, and uterine adenomyosis. Rarely, congenital malformations, intrauterine devices, certain cancers, and pelvic infections cause secondary dysmenorrhea.[18] If the pain occurs between menstrual periods, lasts longer than the first few days of the period, or is not adequately relieved by the use of non-steroidal anti-inflammatory drugs (NSAIDs) or hormonal contraceptives, women should be evaluated for secondary causes of dysmenorrhea.[11]:p. 379
+
+When severe pelvic pain and bleeding suddenly occur or worsen during a cycle, the woman or girl should be evaluated for ectopic pregnancy and spontaneous abortion. This evaluation begins with a pregnancy test and should be done as soon as unusual pain begins, because ectopic pregnancies can be life‑threatening.[21]
+
+In some cases, stronger physical and emotional or psychological sensations may interfere with normal activities, and include menstrual pain (dysmenorrhea), migraine headaches, and depression. Dysmenorrhea, or severe uterine pain, is particularly common for young females (one study found that 67.2% of girls aged 13–19 have it).[22]
+
+Some women experience emotional disturbances starting one or two weeks before their period, and stopping within a few days of the period starting.[6][23] Symptoms may include mental tension, irritability, mood swings, and crying spells. Problems with concentration and memory may occur.[6] There may also be depression or anxiety.[6]
+
+These symptoms can be severe enough to impact a person's performance at work, school, and in every day activities. Greater loss in workplace productivity, quality of life, and greater healthcare costs occur in those with moderate to severe symptoms in comparison to those without these symptoms.[24]
+
+This is part of premenstrual syndrome (PMS) and is estimated to occur in 20 to 30% of women.[5] In 3 to 8% it is severe.[5]
+
+More severe symptoms of anxiety or depression may be signs of premenstrual dysphoric disorder (PMDD). This disorder is listed in the DSM-5 as a depressive disorder.[24] Rarely, in individuals who are susceptible, menstruation may be a trigger for menstrual psychosis.
+
+Extreme psychological stress can also result in periods stopping.[25]
+
+The average volume of menstrual fluid during a monthly menstrual period is 35 milliliters (2.4 tablespoons of menstrual fluid) with 10–80 milliliters (1–6 tablespoons of menstrual fluid) considered typical. Menstrual fluid is the correct name for the flow, although many people prefer to refer to it as menstrual blood. Menstrual fluid is reddish-brown, a slightly darker color than venous blood.[11]:p. 381
+
+About half of menstrual fluid is blood. This blood contains sodium, calcium, phosphate, iron, and chloride, the extent of which depends on the woman. As well as blood, the fluid consists of cervical mucus, vaginal secretions, and endometrial tissue. Vaginal fluids in menses mainly contribute water, common electrolytes, organ moieties, and at least 14 proteins, including glycoproteins.[26]
+
+Many mature females notice blood clots during menstruation. These appear as clumps of blood that may look like tissue. If there are questions (for example, was there an miscarriage or an stillbirth?), examination under a microscope can confirm if it was endometrial tissue or pregnancy tissue (products of conception) that was shed.[27] Sometimes menstrual clots or shed endometrial tissue is incorrectly thought to indicate an early-term miscarriage of an embryo. An enzyme called plasmin – contained in the endometrium – tends to inhibit the blood from clotting.
+
+The amount of iron lost in menstrual fluid is relatively small for most women.[28] In one study, premenopausal women who exhibited symptoms of iron deficiency were given endoscopies. 86% of them actually had gastrointestinal disease and were at risk of being misdiagnosed simply because they were menstruating.[29] Heavy menstrual bleeding, occurring monthly, can result in anemia.
+
+There is a wide spectrum of differences in how women experience menstruation. There are several ways that someone's menstrual cycle can differ from the norm, any of which should be discussed with a doctor to identify the underlying cause:
+
+There is a movement among gynecologists to discard the terms noted above, which although they are widely used, do not have precise definitions.  Many now argue to describe menstruation in simple terminology, including:
+
+Dysfunctional uterine bleeding is a hormonally caused bleeding abnormality.  Dysfunctional uterine bleeding typically occurs in premenopausal women who do not ovulate normally (i.e. are anovulatory). All these bleeding abnormalities need medical attention; they may indicate hormone imbalances, uterine fibroids, or other problems. As pregnant women may bleed, a pregnancy test forms part of the evaluation of abnormal bleeding.
+
+Women who had undergone female genital mutilation (particularly type III- infibulation)  a practice common in parts of Africa, may experience menstrual problems, such as slow and painful menstruation, that is caused by the near-complete sealing off of the vagina.[31]
+
+Premature or delayed menarche should be investigated if menarche begins before 9 years, if menarche has not begun by age 15, if there is no breast development by age 13, or if there is no period by 3 years after the onset of breast development.[3]
+
+Sexual intercourse during menstruation does not cause damage in and of itself, but the woman's body is more vulnerable during this time. Vaginal pH is higher and thus less acidic than normal,[32] the cervix is lower in its position, the cervical opening is more dilated, and the uterine endometrial lining is absent, thus allowing organisms direct access to the bloodstream through the numerous blood vessels that nourish the uterus. All these conditions increase the chance of infection during menstruation.[33]
+
+Hormonal contraception affects the frequency, duration, severity, volume, and regularity of menstruation and menstrual symptoms.
+
+The most common form of hormonal contraception is the combined birth control pill, which contains both estrogen and progestogen. It is typically taken in 28-day cycles, 21 hormonal pills with either a 7-day break from pills, or 7 placebo pills during which the woman menstruates. Although the primary function of the pill is to prevent pregnancy, it may be used to improve some menstrual symptoms and syndromes which affect menstruation, such as polycystic ovary syndrome (PCOS), endometriosis, adenomyosis, amenorrhea, menstrual cramps, menstrual migraines, menorrhagia (excessive menstrual bleeding), menstruation-related or fibroid-related anemia and dysmenorrhea (painful menstruation) by creating regularity in menstrual cycles and reducing overall menstrual flow.[34][35]
+
+Using the combined birth control pill, it is also possible for a woman to delay or completely eliminate menstrual periods, a practice called menstrual suppression.[36] Some women do this simply for convenience in the short-term,[37] while others prefer to eliminate periods altogether when possible. This can be done either by skipping the placebo pills, or using an extended cycle combined oral contraceptive pill, which were first marketed in the U.S. in the early 2000s. This continuous administration of active pills without the placebo can lead to the achievement of amenorrhea in 80% of users within 1 year of use.[38]
+
+Injections such as depo-provera (DMPA) became available in the 1960s and later became used to also achieve amenorrhea. A majority of patients will achieve amenorrhea within 1 year of initiating DMPA therapy. DMPA therapy is typically successful in achieving amenorrhea but also has side effects of decreased bone mineral density that must be considered before beginning therapy.[38]
+
+Levonorgestrel intrauterine devices have also been used been shown to induce amenorrhea. The lower dose device has a lower rate of achieving amenorrhea compared to the higher dose device where 50% of users have been found to achieve amenorrhea within 1 year of use. A concern for usage of these devices  is the invasive administration and initial breakthrough bleeding while utilizing these devices however they have the advantage of the most infrequent dosing schedule of every 5 years. Use of intrauterine devices have also shown to reduce menorrhagia and dysmenorrhea.[38][39]
+
+When using the subdermal progestin only implants, unpredictable bleeding continues and amenorrhea is not commonly achieved amongst patients.[38]Progestogen-only contraceptive pills (sometimes called the 'mini pill') are taken continuously without a 7-day span of using placebo pills, and therefore menstrual periods are less likely to occur than with the combined pill with placebo pills. However, disturbance of the menstrual cycle is common with the mini-pill; 1/3-1/2 of women taking it will experience prolonged periods, and up to 70% experience break-through bleeding (metrorrhagia). Irregular and prolonged bleeding is the most common reason that women discontinue using the mini pill.[40]
+
+When the first birth control pill was being developed, the researchers were aware that they could use the contraceptive to space menstrual periods up to 90 days apart, but they settled on a 28-day cycle that would mimic a natural menstrual cycle and produce monthly periods.  The intention behind this decision was the hope of the inventor, John Rock, to win approval for his invention from the Roman Catholic Church. That attempt failed, but the 28-day cycle remained the standard when the pill became available to the public.[41]
+
+There is debate among medical researchers about the potential long-term impacts of these practices upon female health. Some researchers point to the fact that historically, females have had far fewer menstrual periods throughout their lifetimes, a result of shorter life expectancies, as well as a greater length of time spent pregnant or breast-feeding, which reduced the number of periods experienced by females.[42] There is also the advantage of inducing menstrual suppression amongst people with extreme cognitive and physical disabilities who may not be able to properly manage their menstrual hygiene even with the use of a caregiver.[43] On the other hand, some researchers believe there is a greater potential for negative impacts from exposing females perhaps unnecessarily to regular low doses of synthetic hormones over their reproductive years.[44] There is limited evidence that the act of menstrual suppression directly causes physiologic harm and the primary disadvantages shown to be associated with menstrual suppression are due to side effects of the methods used to achieve amenorrhea.[38][43]
+
+Breastfeeding causes negative feedback to occur on pulse secretion of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH). Depending on the strength of the negative feedback, breastfeeding women may experience complete suppression of follicular development, follicular development but no ovulation, or normal menstrual cycles may resume.[45] Suppression of ovulation is more likely when suckling occurs more frequently.[46] The production of prolactin in response to suckling is important to maintaining lactational amenorrhea.[47] On average, women who are fully breastfeeding whose infants suckle frequently experience a return of menstruation at fourteen and a half months postpartum. There is a wide range of response among individual breastfeeding women, however, with some experiencing return of menstruation at two months and others remaining amenorrheic for up to 42 months postpartum.[48]
+
+Menstruating women manage menstruation primarily by wearing menstrual products such as tampons, napkins or menstrual cups. These products catch the menstrual blood to prevent it from staining and damaging clothing and inconveniencing the wearer. Menstruation can also be suppressed altogether through certain methods of birth control.[49]
+
+Due to poverty, some cannot afford commercial feminine hygiene products.[50][51] Instead, they use materials found in the environment or other improvised materials. Absorption materials that may be used by women who cannot afford anything else include: sand, ash, small hole in earth,[52] cloth, whole leaf, leaf fiber (such as water hyacinth, banana, papyrus, cotton fibre), paper (toilet paper, re-used newspaper, brown paper bags, pulped and dried paper),[53] animal pelt (such as goat skin),[52] double layer of underwear, socks, skirt, or sari.[51][54]
+
+Menstrual products (also called "feminine hygiene" products) are made to absorb or catch menstrual blood. A number of different products are available - some are disposable, some are reusable. Where women can afford it, items used to absorb or catch menses are usually commercially manufactured products.
+
+There are disposable products:
+
+Reusable products include:
+
+Menstrual hygiene products are considered by many states within the United States as "tangible individual property" resulting in additional sales tax. This additional tax increases the overall price and further limits accessibility to menstrual hygiene products to lower income women. These products are classified as medical devices but are not eligible for purchase through government funded assistance programs.[55] The Scottish government have in 2019 begun providing free sanitary products for poorer students at schools, with hopes that this will be rolled out across the entire nation.[56][57]
+
+In developing countries, women experience the lack of access to affordable menstrual hygiene products in addition to a lack of access to other services such as sanitation and waste disposal systems needed to manage their menstrual cycles. Lack of access to waste disposal leads women to throw used products in toilet systems, pit latrines, or discarded in to open areas such as bodies of water. These practices pose dangers to workers who handle these wastes as it increases possible exposure to bloodborne infections in soaked menstrual products and exposure to chemicals found in menstrual hygiene products. Inappropriate disposal also creates pressures on sanitation systems as menstrual hygiene products create sewage blockages.[50] The effects of these inadequate facilities has been shown to have social effects on girls in developing countries leading to school absenteeism.[58]
+
+The most common treatment for menstrual cramps are non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs can be used to reduce moderate to severe pain, and all appear similar.[59] About 1 in 5 women do not respond to NSAIDs and require alternative therapy, such as simple analgesics or heat pads.[60] Other medications for pain management include aspirin or paracetamol and combined oral contraceptives. Although combined oral contraceptives may be used, there is insufficient evidence for the efficacy of intrauterine progestogens.[61]
+
+One review found tentative evidence that acupuncture may be useful, at least in the short term.[62] Another review found insufficient evidence to determine an effect.[63]
+
+Period poverty is a global issue affecting women and girls who do not have access to safe, hygienic sanitary products.[64]
+
+Many religions have menstruation-related traditions, for example: Islam prohibits sexual contact with women during menstruation in the 2nd chapter of the Quran. Some scholars argue that menstruating women are in a state in which they are unable to maintain wudhu, and are therefore prohibited from touching the Arabic version of the Qur'an. Other biological and involuntary functions such as vomiting, bleeding, sexual intercourse, and going to the bathroom also invalidate one's wudhu.[65] In Judaism, a woman during menstruation is called Niddah and may be banned from certain actions. For example, the Jewish Torah prohibits sexual intercourse with a menstruating woman.[66] In Hinduism, menstruating women are traditionally considered ritually impure and given rules to follow.[citation needed] Western civilization, which has been predominantly Christian, has a history of menstrual taboos.[citation needed]
+
+Menstruation education is frequently taught in combination with sex education at school in Western countries, although girls may prefer their mothers to be the primary source of information about menstruation and puberty.[67] Information about menstruation is often shared among friends and peers, which may promote a more positive outlook on puberty.[68] The quality of menstrual education in a society determines the accuracy of people's understanding of the process.[69] In many Western countries where menstruation is a taboo subject, girls tend to conceal the fact that they may be menstruating and struggle to ensure that they give no sign of menstruation.[69] Effective educational programs are essential to providing children and adolescents with clear and accurate information about menstruation. Schools can be an appropriate place for menstrual education to take place.[70] Programs led by peers or third-party agencies are another option.[70] Low-income girls are less likely to receive proper sex education on puberty, leading to a decreased understanding of why menstruation occurs and the associated physiological changes that take place. This has been shown to cause the development of a negative attitude towards menstruation.[71]
+
+Most female mammals have an estrous cycle, yet only ten primate species, four bat species, the elephant shrew and the spiny mouse have a menstrual cycle.[72][73] The lack of immediate relationship between these groups suggests that four distinct evolutionary events have caused menstruation to arise.[74]
+
+Some anthropologists have questioned the energy cost of rebuilding the endometrium every fertility cycle. It has proposed that the energy savings of not having to continuously maintain the uterine lining more than offsets energy cost of having to rebuild the lining in the next fertility cycle, even in species such as humans where much of the lining is lost through bleeding (overt menstruation) rather than reabsorbed (covert menstruation).[75][76]
+
+Many have questioned the evolution of overt menstruation in humans and related species, speculating on what advantage there could be to losing blood associated with dismantling the endometrium, rather than absorbing it, as most mammals do.  Humans do, in fact, reabsorb about two-thirds of the endometrium each cycle. Some work asserts that overt menstruation does not occur because partial endometrial loss is beneficial in itself.  Rather, the fetal development of these species requires a more developed endometrium, one which is too thick to reabsorb completely. There is a correlation between species that have overt menstruation to those that have a large uterus relative to the adult female body size.[75]
+
+Recent reviews suggest that menstruation itself is not an evolved, adaptive trait. Rather, it is an inherent consequence of spontaneous decidualization evolving as a derived trait from non-spontaneous decidualization.[74]
+
+The grandmother hypothesis is a hypothesis to explain the existence of menopause in human life history by identifying the adaptive value of extended kin networking.
+
+Beginning in 1971, some research suggested that menstrual cycles of cohabiting human females became synchronized (menstrual synchrony). However, there is currently significant dispute as to whether menstrual synchrony exists.[77] A 2013 review concluded that menstrual synchrony likely does not exist.[78]
+

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+
+
+Menstruation, also known as a period or monthly,[1] is the regular discharge of blood and mucosal tissue (known as menses) from the inner lining of the uterus through the vagina.[2] The first period usually begins between twelve and fifteen years of age, a point in time known as menarche.[1] However, periods may occasionally start as young as eight years old and still be considered normal.[2] The average age of the first period is generally later in the developing world, and earlier in the developed world.[3] The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women, and 21 to 31 days in adults (an average of 28 days).[2][3] Bleeding usually lasts around 2 to 7 days.[2] Menstruation stops occurring after menopause, which usually occurs between 45 and 55 years of age.[4] Periods also stop during pregnancy and typically do not resume during the initial months of breastfeeding.[2]
+
+Up to 80% of women report having some symptoms prior to menstruation.[5] Common signs and symptoms include acne, tender breasts, bloating, feeling tired, irritability, and mood changes.[6] These may interfere with normal life, therefore qualifying as premenstrual syndrome, in 20 to 30% of women.[5] In 3 to 8%, symptoms are severe.[5]
+
+A lack of periods, known as amenorrhea, is when periods do not occur by age 15 or have not occurred in 90 days.[2] Other problems with the menstrual cycle include painful periods and abnormal bleeding such as bleeding between periods or heavy bleeding.[2] Menstruation in other animals occur in primates (apes and monkeys).[7][8]
+
+The menstrual cycle occurs due to the rise and fall of hormones.[2] This cycle results in the thickening of the lining of the uterus, and the growth of an egg, (which is required for pregnancy).[2] The egg is released from an ovary around day fourteen in the cycle; the thickened lining of the uterus provides nutrients to an embryo after implantation.[2] If implantation does not occur, the lining is released in what is known as menstruation.[2]
+
+The first menstrual period occurs after the onset of pubertal growth, and is called menarche. The average age of menarche is 12 to 15.[1][9] However, it may start as early as eight.[2] The average age of the first period is generally later in the developing world, and earlier in the developed world.[3] The average age of menarche has changed little in the United States since the 1950s.[3]
+
+Menstruation is the most visible phase of the menstrual cycle and its beginning is used as the marker between cycles. The first day of menstrual bleeding is the date used for the last menstrual period (LMP). The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women, and 21 to 31 days in adults.[2][3] The average length is 28 days; one study estimated it at 29.3 days.[10]
+
+Perimenopause is when fertility in a female declines, and menstruation occurs less regularly in the years leading up to the final menstrual period, when a female stops menstruating completely and is no longer fertile. The medical definition of menopause is one year without a period and typically occurs between 45 and 55 in Western countries.[4][11]:p. 381
+
+During pregnancy and for some time after childbirth, menstruation does not occur. The average length of postpartum amenorrhoea is longer when breastfeeding; this is termed lactational amenorrhoea.
+
+In most women, various physical changes are brought about by fluctuations in hormone levels during the menstrual cycle. This includes muscle contractions of the uterus (menstrual cramping) that can precede or accompany menstruation. Some may notice bloating, changes in sex drive, fatigue, breast tenderness, headaches, or irritability before the onset of their period.[12][13][14] It is unclear if the breast discomfort and bloating is related to electrolyte changes or water retention.[15] Some women have mild or no symptoms before the onset of their periods.[13] A healthy diet, reduced consumption of salt, caffeine and alcohol, and regular exercise may be effective for women in controlling water retention.[16] Severe symptoms that disrupt daily activities and functioning may be diagnosed as premenstrual dysphoric disorder.[13]
+
+Many women experience painful cramps, also known as dysmenorrhea, during menstruation.[17]
+
+Painful menstrual cramps that result from an excess of prostaglandin release are referred to as primary dysmenorrhea. Primary dysmenorrhea usually begins within a year or two of menarche, typically with the onset of ovulatory cycles.[18] Treatments that target the mechanism of pain include non-steroidal anti-inflammatory drugs (NSAIDs) and hormonal contraceptives. NSAIDs inhibit prostaglandin production. With long-term treatment, hormonal birth control reduces the amount of uterine fluid/tissue expelled from the uterus. Thus resulting in shorter, less painful menstruation.[19] These drugs are typically more effective than treatments that do not target the source of the pain (e.g. acetaminophen).[20] Risk factors for primary dysmenorrhea include: early age at menarche, long or heavy menstrual periods, smoking, and a family history of dysmenorrhea.[18] Regular physical activity may limit the severity of uterine cramps.[18]
+
+For many women, primary dysmenorrhea gradually subsides in late second generation. Pregnancy has also been demonstrated to lessen the severity of dysmenorrhea, when menstruation resumes.  However, dysmenorrhea can continue until menopause. 5–15% of women with dysmenorrhea experience symptoms severe enough to interfere with daily activities.[18]
+
+Secondary dysmenorrhea is the diagnosis given when menstruation pain is a secondary cause to another disorder. Conditions causing secondary dysmenorrhea include endometriosis, uterine fibroids, and uterine adenomyosis. Rarely, congenital malformations, intrauterine devices, certain cancers, and pelvic infections cause secondary dysmenorrhea.[18] If the pain occurs between menstrual periods, lasts longer than the first few days of the period, or is not adequately relieved by the use of non-steroidal anti-inflammatory drugs (NSAIDs) or hormonal contraceptives, women should be evaluated for secondary causes of dysmenorrhea.[11]:p. 379
+
+When severe pelvic pain and bleeding suddenly occur or worsen during a cycle, the woman or girl should be evaluated for ectopic pregnancy and spontaneous abortion. This evaluation begins with a pregnancy test and should be done as soon as unusual pain begins, because ectopic pregnancies can be life‑threatening.[21]
+
+In some cases, stronger physical and emotional or psychological sensations may interfere with normal activities, and include menstrual pain (dysmenorrhea), migraine headaches, and depression. Dysmenorrhea, or severe uterine pain, is particularly common for young females (one study found that 67.2% of girls aged 13–19 have it).[22]
+
+Some women experience emotional disturbances starting one or two weeks before their period, and stopping within a few days of the period starting.[6][23] Symptoms may include mental tension, irritability, mood swings, and crying spells. Problems with concentration and memory may occur.[6] There may also be depression or anxiety.[6]
+
+These symptoms can be severe enough to impact a person's performance at work, school, and in every day activities. Greater loss in workplace productivity, quality of life, and greater healthcare costs occur in those with moderate to severe symptoms in comparison to those without these symptoms.[24]
+
+This is part of premenstrual syndrome (PMS) and is estimated to occur in 20 to 30% of women.[5] In 3 to 8% it is severe.[5]
+
+More severe symptoms of anxiety or depression may be signs of premenstrual dysphoric disorder (PMDD). This disorder is listed in the DSM-5 as a depressive disorder.[24] Rarely, in individuals who are susceptible, menstruation may be a trigger for menstrual psychosis.
+
+Extreme psychological stress can also result in periods stopping.[25]
+
+The average volume of menstrual fluid during a monthly menstrual period is 35 milliliters (2.4 tablespoons of menstrual fluid) with 10–80 milliliters (1–6 tablespoons of menstrual fluid) considered typical. Menstrual fluid is the correct name for the flow, although many people prefer to refer to it as menstrual blood. Menstrual fluid is reddish-brown, a slightly darker color than venous blood.[11]:p. 381
+
+About half of menstrual fluid is blood. This blood contains sodium, calcium, phosphate, iron, and chloride, the extent of which depends on the woman. As well as blood, the fluid consists of cervical mucus, vaginal secretions, and endometrial tissue. Vaginal fluids in menses mainly contribute water, common electrolytes, organ moieties, and at least 14 proteins, including glycoproteins.[26]
+
+Many mature females notice blood clots during menstruation. These appear as clumps of blood that may look like tissue. If there are questions (for example, was there an miscarriage or an stillbirth?), examination under a microscope can confirm if it was endometrial tissue or pregnancy tissue (products of conception) that was shed.[27] Sometimes menstrual clots or shed endometrial tissue is incorrectly thought to indicate an early-term miscarriage of an embryo. An enzyme called plasmin – contained in the endometrium – tends to inhibit the blood from clotting.
+
+The amount of iron lost in menstrual fluid is relatively small for most women.[28] In one study, premenopausal women who exhibited symptoms of iron deficiency were given endoscopies. 86% of them actually had gastrointestinal disease and were at risk of being misdiagnosed simply because they were menstruating.[29] Heavy menstrual bleeding, occurring monthly, can result in anemia.
+
+There is a wide spectrum of differences in how women experience menstruation. There are several ways that someone's menstrual cycle can differ from the norm, any of which should be discussed with a doctor to identify the underlying cause:
+
+There is a movement among gynecologists to discard the terms noted above, which although they are widely used, do not have precise definitions.  Many now argue to describe menstruation in simple terminology, including:
+
+Dysfunctional uterine bleeding is a hormonally caused bleeding abnormality.  Dysfunctional uterine bleeding typically occurs in premenopausal women who do not ovulate normally (i.e. are anovulatory). All these bleeding abnormalities need medical attention; they may indicate hormone imbalances, uterine fibroids, or other problems. As pregnant women may bleed, a pregnancy test forms part of the evaluation of abnormal bleeding.
+
+Women who had undergone female genital mutilation (particularly type III- infibulation)  a practice common in parts of Africa, may experience menstrual problems, such as slow and painful menstruation, that is caused by the near-complete sealing off of the vagina.[31]
+
+Premature or delayed menarche should be investigated if menarche begins before 9 years, if menarche has not begun by age 15, if there is no breast development by age 13, or if there is no period by 3 years after the onset of breast development.[3]
+
+Sexual intercourse during menstruation does not cause damage in and of itself, but the woman's body is more vulnerable during this time. Vaginal pH is higher and thus less acidic than normal,[32] the cervix is lower in its position, the cervical opening is more dilated, and the uterine endometrial lining is absent, thus allowing organisms direct access to the bloodstream through the numerous blood vessels that nourish the uterus. All these conditions increase the chance of infection during menstruation.[33]
+
+Hormonal contraception affects the frequency, duration, severity, volume, and regularity of menstruation and menstrual symptoms.
+
+The most common form of hormonal contraception is the combined birth control pill, which contains both estrogen and progestogen. It is typically taken in 28-day cycles, 21 hormonal pills with either a 7-day break from pills, or 7 placebo pills during which the woman menstruates. Although the primary function of the pill is to prevent pregnancy, it may be used to improve some menstrual symptoms and syndromes which affect menstruation, such as polycystic ovary syndrome (PCOS), endometriosis, adenomyosis, amenorrhea, menstrual cramps, menstrual migraines, menorrhagia (excessive menstrual bleeding), menstruation-related or fibroid-related anemia and dysmenorrhea (painful menstruation) by creating regularity in menstrual cycles and reducing overall menstrual flow.[34][35]
+
+Using the combined birth control pill, it is also possible for a woman to delay or completely eliminate menstrual periods, a practice called menstrual suppression.[36] Some women do this simply for convenience in the short-term,[37] while others prefer to eliminate periods altogether when possible. This can be done either by skipping the placebo pills, or using an extended cycle combined oral contraceptive pill, which were first marketed in the U.S. in the early 2000s. This continuous administration of active pills without the placebo can lead to the achievement of amenorrhea in 80% of users within 1 year of use.[38]
+
+Injections such as depo-provera (DMPA) became available in the 1960s and later became used to also achieve amenorrhea. A majority of patients will achieve amenorrhea within 1 year of initiating DMPA therapy. DMPA therapy is typically successful in achieving amenorrhea but also has side effects of decreased bone mineral density that must be considered before beginning therapy.[38]
+
+Levonorgestrel intrauterine devices have also been used been shown to induce amenorrhea. The lower dose device has a lower rate of achieving amenorrhea compared to the higher dose device where 50% of users have been found to achieve amenorrhea within 1 year of use. A concern for usage of these devices  is the invasive administration and initial breakthrough bleeding while utilizing these devices however they have the advantage of the most infrequent dosing schedule of every 5 years. Use of intrauterine devices have also shown to reduce menorrhagia and dysmenorrhea.[38][39]
+
+When using the subdermal progestin only implants, unpredictable bleeding continues and amenorrhea is not commonly achieved amongst patients.[38]Progestogen-only contraceptive pills (sometimes called the 'mini pill') are taken continuously without a 7-day span of using placebo pills, and therefore menstrual periods are less likely to occur than with the combined pill with placebo pills. However, disturbance of the menstrual cycle is common with the mini-pill; 1/3-1/2 of women taking it will experience prolonged periods, and up to 70% experience break-through bleeding (metrorrhagia). Irregular and prolonged bleeding is the most common reason that women discontinue using the mini pill.[40]
+
+When the first birth control pill was being developed, the researchers were aware that they could use the contraceptive to space menstrual periods up to 90 days apart, but they settled on a 28-day cycle that would mimic a natural menstrual cycle and produce monthly periods.  The intention behind this decision was the hope of the inventor, John Rock, to win approval for his invention from the Roman Catholic Church. That attempt failed, but the 28-day cycle remained the standard when the pill became available to the public.[41]
+
+There is debate among medical researchers about the potential long-term impacts of these practices upon female health. Some researchers point to the fact that historically, females have had far fewer menstrual periods throughout their lifetimes, a result of shorter life expectancies, as well as a greater length of time spent pregnant or breast-feeding, which reduced the number of periods experienced by females.[42] There is also the advantage of inducing menstrual suppression amongst people with extreme cognitive and physical disabilities who may not be able to properly manage their menstrual hygiene even with the use of a caregiver.[43] On the other hand, some researchers believe there is a greater potential for negative impacts from exposing females perhaps unnecessarily to regular low doses of synthetic hormones over their reproductive years.[44] There is limited evidence that the act of menstrual suppression directly causes physiologic harm and the primary disadvantages shown to be associated with menstrual suppression are due to side effects of the methods used to achieve amenorrhea.[38][43]
+
+Breastfeeding causes negative feedback to occur on pulse secretion of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH). Depending on the strength of the negative feedback, breastfeeding women may experience complete suppression of follicular development, follicular development but no ovulation, or normal menstrual cycles may resume.[45] Suppression of ovulation is more likely when suckling occurs more frequently.[46] The production of prolactin in response to suckling is important to maintaining lactational amenorrhea.[47] On average, women who are fully breastfeeding whose infants suckle frequently experience a return of menstruation at fourteen and a half months postpartum. There is a wide range of response among individual breastfeeding women, however, with some experiencing return of menstruation at two months and others remaining amenorrheic for up to 42 months postpartum.[48]
+
+Menstruating women manage menstruation primarily by wearing menstrual products such as tampons, napkins or menstrual cups. These products catch the menstrual blood to prevent it from staining and damaging clothing and inconveniencing the wearer. Menstruation can also be suppressed altogether through certain methods of birth control.[49]
+
+Due to poverty, some cannot afford commercial feminine hygiene products.[50][51] Instead, they use materials found in the environment or other improvised materials. Absorption materials that may be used by women who cannot afford anything else include: sand, ash, small hole in earth,[52] cloth, whole leaf, leaf fiber (such as water hyacinth, banana, papyrus, cotton fibre), paper (toilet paper, re-used newspaper, brown paper bags, pulped and dried paper),[53] animal pelt (such as goat skin),[52] double layer of underwear, socks, skirt, or sari.[51][54]
+
+Menstrual products (also called "feminine hygiene" products) are made to absorb or catch menstrual blood. A number of different products are available - some are disposable, some are reusable. Where women can afford it, items used to absorb or catch menses are usually commercially manufactured products.
+
+There are disposable products:
+
+Reusable products include:
+
+Menstrual hygiene products are considered by many states within the United States as "tangible individual property" resulting in additional sales tax. This additional tax increases the overall price and further limits accessibility to menstrual hygiene products to lower income women. These products are classified as medical devices but are not eligible for purchase through government funded assistance programs.[55] The Scottish government have in 2019 begun providing free sanitary products for poorer students at schools, with hopes that this will be rolled out across the entire nation.[56][57]
+
+In developing countries, women experience the lack of access to affordable menstrual hygiene products in addition to a lack of access to other services such as sanitation and waste disposal systems needed to manage their menstrual cycles. Lack of access to waste disposal leads women to throw used products in toilet systems, pit latrines, or discarded in to open areas such as bodies of water. These practices pose dangers to workers who handle these wastes as it increases possible exposure to bloodborne infections in soaked menstrual products and exposure to chemicals found in menstrual hygiene products. Inappropriate disposal also creates pressures on sanitation systems as menstrual hygiene products create sewage blockages.[50] The effects of these inadequate facilities has been shown to have social effects on girls in developing countries leading to school absenteeism.[58]
+
+The most common treatment for menstrual cramps are non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs can be used to reduce moderate to severe pain, and all appear similar.[59] About 1 in 5 women do not respond to NSAIDs and require alternative therapy, such as simple analgesics or heat pads.[60] Other medications for pain management include aspirin or paracetamol and combined oral contraceptives. Although combined oral contraceptives may be used, there is insufficient evidence for the efficacy of intrauterine progestogens.[61]
+
+One review found tentative evidence that acupuncture may be useful, at least in the short term.[62] Another review found insufficient evidence to determine an effect.[63]
+
+Period poverty is a global issue affecting women and girls who do not have access to safe, hygienic sanitary products.[64]
+
+Many religions have menstruation-related traditions, for example: Islam prohibits sexual contact with women during menstruation in the 2nd chapter of the Quran. Some scholars argue that menstruating women are in a state in which they are unable to maintain wudhu, and are therefore prohibited from touching the Arabic version of the Qur'an. Other biological and involuntary functions such as vomiting, bleeding, sexual intercourse, and going to the bathroom also invalidate one's wudhu.[65] In Judaism, a woman during menstruation is called Niddah and may be banned from certain actions. For example, the Jewish Torah prohibits sexual intercourse with a menstruating woman.[66] In Hinduism, menstruating women are traditionally considered ritually impure and given rules to follow.[citation needed] Western civilization, which has been predominantly Christian, has a history of menstrual taboos.[citation needed]
+
+Menstruation education is frequently taught in combination with sex education at school in Western countries, although girls may prefer their mothers to be the primary source of information about menstruation and puberty.[67] Information about menstruation is often shared among friends and peers, which may promote a more positive outlook on puberty.[68] The quality of menstrual education in a society determines the accuracy of people's understanding of the process.[69] In many Western countries where menstruation is a taboo subject, girls tend to conceal the fact that they may be menstruating and struggle to ensure that they give no sign of menstruation.[69] Effective educational programs are essential to providing children and adolescents with clear and accurate information about menstruation. Schools can be an appropriate place for menstrual education to take place.[70] Programs led by peers or third-party agencies are another option.[70] Low-income girls are less likely to receive proper sex education on puberty, leading to a decreased understanding of why menstruation occurs and the associated physiological changes that take place. This has been shown to cause the development of a negative attitude towards menstruation.[71]
+
+Most female mammals have an estrous cycle, yet only ten primate species, four bat species, the elephant shrew and the spiny mouse have a menstrual cycle.[72][73] The lack of immediate relationship between these groups suggests that four distinct evolutionary events have caused menstruation to arise.[74]
+
+Some anthropologists have questioned the energy cost of rebuilding the endometrium every fertility cycle. It has proposed that the energy savings of not having to continuously maintain the uterine lining more than offsets energy cost of having to rebuild the lining in the next fertility cycle, even in species such as humans where much of the lining is lost through bleeding (overt menstruation) rather than reabsorbed (covert menstruation).[75][76]
+
+Many have questioned the evolution of overt menstruation in humans and related species, speculating on what advantage there could be to losing blood associated with dismantling the endometrium, rather than absorbing it, as most mammals do.  Humans do, in fact, reabsorb about two-thirds of the endometrium each cycle. Some work asserts that overt menstruation does not occur because partial endometrial loss is beneficial in itself.  Rather, the fetal development of these species requires a more developed endometrium, one which is too thick to reabsorb completely. There is a correlation between species that have overt menstruation to those that have a large uterus relative to the adult female body size.[75]
+
+Recent reviews suggest that menstruation itself is not an evolved, adaptive trait. Rather, it is an inherent consequence of spontaneous decidualization evolving as a derived trait from non-spontaneous decidualization.[74]
+
+The grandmother hypothesis is a hypothesis to explain the existence of menopause in human life history by identifying the adaptive value of extended kin networking.
+
+Beginning in 1971, some research suggested that menstrual cycles of cohabiting human females became synchronized (menstrual synchrony). However, there is currently significant dispute as to whether menstrual synchrony exists.[77] A 2013 review concluded that menstrual synchrony likely does not exist.[78]
+

en/3769.html.txt

@@ -0,0 +1,116 @@
+
+
+Menstruation, also known as a period or monthly,[1] is the regular discharge of blood and mucosal tissue (known as menses) from the inner lining of the uterus through the vagina.[2] The first period usually begins between twelve and fifteen years of age, a point in time known as menarche.[1] However, periods may occasionally start as young as eight years old and still be considered normal.[2] The average age of the first period is generally later in the developing world, and earlier in the developed world.[3] The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women, and 21 to 31 days in adults (an average of 28 days).[2][3] Bleeding usually lasts around 2 to 7 days.[2] Menstruation stops occurring after menopause, which usually occurs between 45 and 55 years of age.[4] Periods also stop during pregnancy and typically do not resume during the initial months of breastfeeding.[2]
+
+Up to 80% of women report having some symptoms prior to menstruation.[5] Common signs and symptoms include acne, tender breasts, bloating, feeling tired, irritability, and mood changes.[6] These may interfere with normal life, therefore qualifying as premenstrual syndrome, in 20 to 30% of women.[5] In 3 to 8%, symptoms are severe.[5]
+
+A lack of periods, known as amenorrhea, is when periods do not occur by age 15 or have not occurred in 90 days.[2] Other problems with the menstrual cycle include painful periods and abnormal bleeding such as bleeding between periods or heavy bleeding.[2] Menstruation in other animals occur in primates (apes and monkeys).[7][8]
+
+The menstrual cycle occurs due to the rise and fall of hormones.[2] This cycle results in the thickening of the lining of the uterus, and the growth of an egg, (which is required for pregnancy).[2] The egg is released from an ovary around day fourteen in the cycle; the thickened lining of the uterus provides nutrients to an embryo after implantation.[2] If implantation does not occur, the lining is released in what is known as menstruation.[2]
+
+The first menstrual period occurs after the onset of pubertal growth, and is called menarche. The average age of menarche is 12 to 15.[1][9] However, it may start as early as eight.[2] The average age of the first period is generally later in the developing world, and earlier in the developed world.[3] The average age of menarche has changed little in the United States since the 1950s.[3]
+
+Menstruation is the most visible phase of the menstrual cycle and its beginning is used as the marker between cycles. The first day of menstrual bleeding is the date used for the last menstrual period (LMP). The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women, and 21 to 31 days in adults.[2][3] The average length is 28 days; one study estimated it at 29.3 days.[10]
+
+Perimenopause is when fertility in a female declines, and menstruation occurs less regularly in the years leading up to the final menstrual period, when a female stops menstruating completely and is no longer fertile. The medical definition of menopause is one year without a period and typically occurs between 45 and 55 in Western countries.[4][11]:p. 381
+
+During pregnancy and for some time after childbirth, menstruation does not occur. The average length of postpartum amenorrhoea is longer when breastfeeding; this is termed lactational amenorrhoea.
+
+In most women, various physical changes are brought about by fluctuations in hormone levels during the menstrual cycle. This includes muscle contractions of the uterus (menstrual cramping) that can precede or accompany menstruation. Some may notice bloating, changes in sex drive, fatigue, breast tenderness, headaches, or irritability before the onset of their period.[12][13][14] It is unclear if the breast discomfort and bloating is related to electrolyte changes or water retention.[15] Some women have mild or no symptoms before the onset of their periods.[13] A healthy diet, reduced consumption of salt, caffeine and alcohol, and regular exercise may be effective for women in controlling water retention.[16] Severe symptoms that disrupt daily activities and functioning may be diagnosed as premenstrual dysphoric disorder.[13]
+
+Many women experience painful cramps, also known as dysmenorrhea, during menstruation.[17]
+
+Painful menstrual cramps that result from an excess of prostaglandin release are referred to as primary dysmenorrhea. Primary dysmenorrhea usually begins within a year or two of menarche, typically with the onset of ovulatory cycles.[18] Treatments that target the mechanism of pain include non-steroidal anti-inflammatory drugs (NSAIDs) and hormonal contraceptives. NSAIDs inhibit prostaglandin production. With long-term treatment, hormonal birth control reduces the amount of uterine fluid/tissue expelled from the uterus. Thus resulting in shorter, less painful menstruation.[19] These drugs are typically more effective than treatments that do not target the source of the pain (e.g. acetaminophen).[20] Risk factors for primary dysmenorrhea include: early age at menarche, long or heavy menstrual periods, smoking, and a family history of dysmenorrhea.[18] Regular physical activity may limit the severity of uterine cramps.[18]
+
+For many women, primary dysmenorrhea gradually subsides in late second generation. Pregnancy has also been demonstrated to lessen the severity of dysmenorrhea, when menstruation resumes.  However, dysmenorrhea can continue until menopause. 5–15% of women with dysmenorrhea experience symptoms severe enough to interfere with daily activities.[18]
+
+Secondary dysmenorrhea is the diagnosis given when menstruation pain is a secondary cause to another disorder. Conditions causing secondary dysmenorrhea include endometriosis, uterine fibroids, and uterine adenomyosis. Rarely, congenital malformations, intrauterine devices, certain cancers, and pelvic infections cause secondary dysmenorrhea.[18] If the pain occurs between menstrual periods, lasts longer than the first few days of the period, or is not adequately relieved by the use of non-steroidal anti-inflammatory drugs (NSAIDs) or hormonal contraceptives, women should be evaluated for secondary causes of dysmenorrhea.[11]:p. 379
+
+When severe pelvic pain and bleeding suddenly occur or worsen during a cycle, the woman or girl should be evaluated for ectopic pregnancy and spontaneous abortion. This evaluation begins with a pregnancy test and should be done as soon as unusual pain begins, because ectopic pregnancies can be life‑threatening.[21]
+
+In some cases, stronger physical and emotional or psychological sensations may interfere with normal activities, and include menstrual pain (dysmenorrhea), migraine headaches, and depression. Dysmenorrhea, or severe uterine pain, is particularly common for young females (one study found that 67.2% of girls aged 13–19 have it).[22]
+
+Some women experience emotional disturbances starting one or two weeks before their period, and stopping within a few days of the period starting.[6][23] Symptoms may include mental tension, irritability, mood swings, and crying spells. Problems with concentration and memory may occur.[6] There may also be depression or anxiety.[6]
+
+These symptoms can be severe enough to impact a person's performance at work, school, and in every day activities. Greater loss in workplace productivity, quality of life, and greater healthcare costs occur in those with moderate to severe symptoms in comparison to those without these symptoms.[24]
+
+This is part of premenstrual syndrome (PMS) and is estimated to occur in 20 to 30% of women.[5] In 3 to 8% it is severe.[5]
+
+More severe symptoms of anxiety or depression may be signs of premenstrual dysphoric disorder (PMDD). This disorder is listed in the DSM-5 as a depressive disorder.[24] Rarely, in individuals who are susceptible, menstruation may be a trigger for menstrual psychosis.
+
+Extreme psychological stress can also result in periods stopping.[25]
+
+The average volume of menstrual fluid during a monthly menstrual period is 35 milliliters (2.4 tablespoons of menstrual fluid) with 10–80 milliliters (1–6 tablespoons of menstrual fluid) considered typical. Menstrual fluid is the correct name for the flow, although many people prefer to refer to it as menstrual blood. Menstrual fluid is reddish-brown, a slightly darker color than venous blood.[11]:p. 381
+
+About half of menstrual fluid is blood. This blood contains sodium, calcium, phosphate, iron, and chloride, the extent of which depends on the woman. As well as blood, the fluid consists of cervical mucus, vaginal secretions, and endometrial tissue. Vaginal fluids in menses mainly contribute water, common electrolytes, organ moieties, and at least 14 proteins, including glycoproteins.[26]
+
+Many mature females notice blood clots during menstruation. These appear as clumps of blood that may look like tissue. If there are questions (for example, was there an miscarriage or an stillbirth?), examination under a microscope can confirm if it was endometrial tissue or pregnancy tissue (products of conception) that was shed.[27] Sometimes menstrual clots or shed endometrial tissue is incorrectly thought to indicate an early-term miscarriage of an embryo. An enzyme called plasmin – contained in the endometrium – tends to inhibit the blood from clotting.
+
+The amount of iron lost in menstrual fluid is relatively small for most women.[28] In one study, premenopausal women who exhibited symptoms of iron deficiency were given endoscopies. 86% of them actually had gastrointestinal disease and were at risk of being misdiagnosed simply because they were menstruating.[29] Heavy menstrual bleeding, occurring monthly, can result in anemia.
+
+There is a wide spectrum of differences in how women experience menstruation. There are several ways that someone's menstrual cycle can differ from the norm, any of which should be discussed with a doctor to identify the underlying cause:
+
+There is a movement among gynecologists to discard the terms noted above, which although they are widely used, do not have precise definitions.  Many now argue to describe menstruation in simple terminology, including:
+
+Dysfunctional uterine bleeding is a hormonally caused bleeding abnormality.  Dysfunctional uterine bleeding typically occurs in premenopausal women who do not ovulate normally (i.e. are anovulatory). All these bleeding abnormalities need medical attention; they may indicate hormone imbalances, uterine fibroids, or other problems. As pregnant women may bleed, a pregnancy test forms part of the evaluation of abnormal bleeding.
+
+Women who had undergone female genital mutilation (particularly type III- infibulation)  a practice common in parts of Africa, may experience menstrual problems, such as slow and painful menstruation, that is caused by the near-complete sealing off of the vagina.[31]
+
+Premature or delayed menarche should be investigated if menarche begins before 9 years, if menarche has not begun by age 15, if there is no breast development by age 13, or if there is no period by 3 years after the onset of breast development.[3]
+
+Sexual intercourse during menstruation does not cause damage in and of itself, but the woman's body is more vulnerable during this time. Vaginal pH is higher and thus less acidic than normal,[32] the cervix is lower in its position, the cervical opening is more dilated, and the uterine endometrial lining is absent, thus allowing organisms direct access to the bloodstream through the numerous blood vessels that nourish the uterus. All these conditions increase the chance of infection during menstruation.[33]
+
+Hormonal contraception affects the frequency, duration, severity, volume, and regularity of menstruation and menstrual symptoms.
+
+The most common form of hormonal contraception is the combined birth control pill, which contains both estrogen and progestogen. It is typically taken in 28-day cycles, 21 hormonal pills with either a 7-day break from pills, or 7 placebo pills during which the woman menstruates. Although the primary function of the pill is to prevent pregnancy, it may be used to improve some menstrual symptoms and syndromes which affect menstruation, such as polycystic ovary syndrome (PCOS), endometriosis, adenomyosis, amenorrhea, menstrual cramps, menstrual migraines, menorrhagia (excessive menstrual bleeding), menstruation-related or fibroid-related anemia and dysmenorrhea (painful menstruation) by creating regularity in menstrual cycles and reducing overall menstrual flow.[34][35]
+
+Using the combined birth control pill, it is also possible for a woman to delay or completely eliminate menstrual periods, a practice called menstrual suppression.[36] Some women do this simply for convenience in the short-term,[37] while others prefer to eliminate periods altogether when possible. This can be done either by skipping the placebo pills, or using an extended cycle combined oral contraceptive pill, which were first marketed in the U.S. in the early 2000s. This continuous administration of active pills without the placebo can lead to the achievement of amenorrhea in 80% of users within 1 year of use.[38]
+
+Injections such as depo-provera (DMPA) became available in the 1960s and later became used to also achieve amenorrhea. A majority of patients will achieve amenorrhea within 1 year of initiating DMPA therapy. DMPA therapy is typically successful in achieving amenorrhea but also has side effects of decreased bone mineral density that must be considered before beginning therapy.[38]
+
+Levonorgestrel intrauterine devices have also been used been shown to induce amenorrhea. The lower dose device has a lower rate of achieving amenorrhea compared to the higher dose device where 50% of users have been found to achieve amenorrhea within 1 year of use. A concern for usage of these devices  is the invasive administration and initial breakthrough bleeding while utilizing these devices however they have the advantage of the most infrequent dosing schedule of every 5 years. Use of intrauterine devices have also shown to reduce menorrhagia and dysmenorrhea.[38][39]
+
+When using the subdermal progestin only implants, unpredictable bleeding continues and amenorrhea is not commonly achieved amongst patients.[38]Progestogen-only contraceptive pills (sometimes called the 'mini pill') are taken continuously without a 7-day span of using placebo pills, and therefore menstrual periods are less likely to occur than with the combined pill with placebo pills. However, disturbance of the menstrual cycle is common with the mini-pill; 1/3-1/2 of women taking it will experience prolonged periods, and up to 70% experience break-through bleeding (metrorrhagia). Irregular and prolonged bleeding is the most common reason that women discontinue using the mini pill.[40]
+
+When the first birth control pill was being developed, the researchers were aware that they could use the contraceptive to space menstrual periods up to 90 days apart, but they settled on a 28-day cycle that would mimic a natural menstrual cycle and produce monthly periods.  The intention behind this decision was the hope of the inventor, John Rock, to win approval for his invention from the Roman Catholic Church. That attempt failed, but the 28-day cycle remained the standard when the pill became available to the public.[41]
+
+There is debate among medical researchers about the potential long-term impacts of these practices upon female health. Some researchers point to the fact that historically, females have had far fewer menstrual periods throughout their lifetimes, a result of shorter life expectancies, as well as a greater length of time spent pregnant or breast-feeding, which reduced the number of periods experienced by females.[42] There is also the advantage of inducing menstrual suppression amongst people with extreme cognitive and physical disabilities who may not be able to properly manage their menstrual hygiene even with the use of a caregiver.[43] On the other hand, some researchers believe there is a greater potential for negative impacts from exposing females perhaps unnecessarily to regular low doses of synthetic hormones over their reproductive years.[44] There is limited evidence that the act of menstrual suppression directly causes physiologic harm and the primary disadvantages shown to be associated with menstrual suppression are due to side effects of the methods used to achieve amenorrhea.[38][43]
+
+Breastfeeding causes negative feedback to occur on pulse secretion of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH). Depending on the strength of the negative feedback, breastfeeding women may experience complete suppression of follicular development, follicular development but no ovulation, or normal menstrual cycles may resume.[45] Suppression of ovulation is more likely when suckling occurs more frequently.[46] The production of prolactin in response to suckling is important to maintaining lactational amenorrhea.[47] On average, women who are fully breastfeeding whose infants suckle frequently experience a return of menstruation at fourteen and a half months postpartum. There is a wide range of response among individual breastfeeding women, however, with some experiencing return of menstruation at two months and others remaining amenorrheic for up to 42 months postpartum.[48]
+
+Menstruating women manage menstruation primarily by wearing menstrual products such as tampons, napkins or menstrual cups. These products catch the menstrual blood to prevent it from staining and damaging clothing and inconveniencing the wearer. Menstruation can also be suppressed altogether through certain methods of birth control.[49]
+
+Due to poverty, some cannot afford commercial feminine hygiene products.[50][51] Instead, they use materials found in the environment or other improvised materials. Absorption materials that may be used by women who cannot afford anything else include: sand, ash, small hole in earth,[52] cloth, whole leaf, leaf fiber (such as water hyacinth, banana, papyrus, cotton fibre), paper (toilet paper, re-used newspaper, brown paper bags, pulped and dried paper),[53] animal pelt (such as goat skin),[52] double layer of underwear, socks, skirt, or sari.[51][54]
+
+Menstrual products (also called "feminine hygiene" products) are made to absorb or catch menstrual blood. A number of different products are available - some are disposable, some are reusable. Where women can afford it, items used to absorb or catch menses are usually commercially manufactured products.
+
+There are disposable products:
+
+Reusable products include:
+
+Menstrual hygiene products are considered by many states within the United States as "tangible individual property" resulting in additional sales tax. This additional tax increases the overall price and further limits accessibility to menstrual hygiene products to lower income women. These products are classified as medical devices but are not eligible for purchase through government funded assistance programs.[55] The Scottish government have in 2019 begun providing free sanitary products for poorer students at schools, with hopes that this will be rolled out across the entire nation.[56][57]
+
+In developing countries, women experience the lack of access to affordable menstrual hygiene products in addition to a lack of access to other services such as sanitation and waste disposal systems needed to manage their menstrual cycles. Lack of access to waste disposal leads women to throw used products in toilet systems, pit latrines, or discarded in to open areas such as bodies of water. These practices pose dangers to workers who handle these wastes as it increases possible exposure to bloodborne infections in soaked menstrual products and exposure to chemicals found in menstrual hygiene products. Inappropriate disposal also creates pressures on sanitation systems as menstrual hygiene products create sewage blockages.[50] The effects of these inadequate facilities has been shown to have social effects on girls in developing countries leading to school absenteeism.[58]
+
+The most common treatment for menstrual cramps are non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs can be used to reduce moderate to severe pain, and all appear similar.[59] About 1 in 5 women do not respond to NSAIDs and require alternative therapy, such as simple analgesics or heat pads.[60] Other medications for pain management include aspirin or paracetamol and combined oral contraceptives. Although combined oral contraceptives may be used, there is insufficient evidence for the efficacy of intrauterine progestogens.[61]
+
+One review found tentative evidence that acupuncture may be useful, at least in the short term.[62] Another review found insufficient evidence to determine an effect.[63]
+
+Period poverty is a global issue affecting women and girls who do not have access to safe, hygienic sanitary products.[64]
+
+Many religions have menstruation-related traditions, for example: Islam prohibits sexual contact with women during menstruation in the 2nd chapter of the Quran. Some scholars argue that menstruating women are in a state in which they are unable to maintain wudhu, and are therefore prohibited from touching the Arabic version of the Qur'an. Other biological and involuntary functions such as vomiting, bleeding, sexual intercourse, and going to the bathroom also invalidate one's wudhu.[65] In Judaism, a woman during menstruation is called Niddah and may be banned from certain actions. For example, the Jewish Torah prohibits sexual intercourse with a menstruating woman.[66] In Hinduism, menstruating women are traditionally considered ritually impure and given rules to follow.[citation needed] Western civilization, which has been predominantly Christian, has a history of menstrual taboos.[citation needed]
+
+Menstruation education is frequently taught in combination with sex education at school in Western countries, although girls may prefer their mothers to be the primary source of information about menstruation and puberty.[67] Information about menstruation is often shared among friends and peers, which may promote a more positive outlook on puberty.[68] The quality of menstrual education in a society determines the accuracy of people's understanding of the process.[69] In many Western countries where menstruation is a taboo subject, girls tend to conceal the fact that they may be menstruating and struggle to ensure that they give no sign of menstruation.[69] Effective educational programs are essential to providing children and adolescents with clear and accurate information about menstruation. Schools can be an appropriate place for menstrual education to take place.[70] Programs led by peers or third-party agencies are another option.[70] Low-income girls are less likely to receive proper sex education on puberty, leading to a decreased understanding of why menstruation occurs and the associated physiological changes that take place. This has been shown to cause the development of a negative attitude towards menstruation.[71]
+
+Most female mammals have an estrous cycle, yet only ten primate species, four bat species, the elephant shrew and the spiny mouse have a menstrual cycle.[72][73] The lack of immediate relationship between these groups suggests that four distinct evolutionary events have caused menstruation to arise.[74]
+
+Some anthropologists have questioned the energy cost of rebuilding the endometrium every fertility cycle. It has proposed that the energy savings of not having to continuously maintain the uterine lining more than offsets energy cost of having to rebuild the lining in the next fertility cycle, even in species such as humans where much of the lining is lost through bleeding (overt menstruation) rather than reabsorbed (covert menstruation).[75][76]
+
+Many have questioned the evolution of overt menstruation in humans and related species, speculating on what advantage there could be to losing blood associated with dismantling the endometrium, rather than absorbing it, as most mammals do.  Humans do, in fact, reabsorb about two-thirds of the endometrium each cycle. Some work asserts that overt menstruation does not occur because partial endometrial loss is beneficial in itself.  Rather, the fetal development of these species requires a more developed endometrium, one which is too thick to reabsorb completely. There is a correlation between species that have overt menstruation to those that have a large uterus relative to the adult female body size.[75]
+
+Recent reviews suggest that menstruation itself is not an evolved, adaptive trait. Rather, it is an inherent consequence of spontaneous decidualization evolving as a derived trait from non-spontaneous decidualization.[74]
+
+The grandmother hypothesis is a hypothesis to explain the existence of menopause in human life history by identifying the adaptive value of extended kin networking.
+
+Beginning in 1971, some research suggested that menstrual cycles of cohabiting human females became synchronized (menstrual synchrony). However, there is currently significant dispute as to whether menstrual synchrony exists.[77] A 2013 review concluded that menstrual synchrony likely does not exist.[78]
+

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+An army (from Latin arma "arms, weapons" via Old French armée, "armed" [feminine]), ground force or land force is a fighting force that fights primarily on land. In the broadest sense, it is the land-based military branch, service branch or armed service of a nation or state. It may also include aviation assets by possessing an army aviation component. Within a national military force, the word army may also mean a field army.
+
+In some countries, such as France and China, the term "army", especially in its plural form "armies", has the broader meaning of armed forces as a whole, while retaining the colloquial sense of land forces. To differentiate the colloquial army from the formal concept of military force, the term is qualified, for example in France the land force is called Armée de terre, meaning Land Army, and the air force is called Armée de l'Air, meaning Air Army. The naval force, although not using the term "army", is also included in the broad sense of the term "armies" — thus the French Navy is an integral component of the collective French Armies (French Armed Forces) under the Ministry of the Armies. A similar pattern is seen in China, with the People's Liberation Army (PLA) being the overall military, the "actual army" being the PLA Ground Force, and so forth for the PLA Air Force, the PLA Navy, and other branches.
+
+The current largest army in the world, by number of active troops, is the PLA Ground Force of China with 1,600,000 active troops and 510,000 reserve personnel followed by the Indian Army with 1,237,117 active troops and 960,000 reserve personnel.
+
+By convention, irregular military is understood in contrast to regular armies which grew slowly from personal bodyguards or elite militia. Regular in this case refers to standardized doctrines, uniforms, organizations, etc. Regular military can also refer to full-time status (standing army), versus reserve or part-time personnel. Other distinctions may separate statutory forces (established under laws such as the National Defence Act), from de facto "non-statutory" forces such as some guerrilla and revolutionary armies. Armies may also be expeditionary (designed for overseas or international deployment) or fencible (designed for – or restricted to – homeland defence)
+
+India's armies were among the first in the world. The first recorded battle, the Battle of the Ten Kings, happened when a Hindu Aryan king named Sudas defeated an alliance of ten kings and their supportive chieftains. During the Iron Age, the Maurya and Nanda Empires had the largest armies in the world, the peak being approximately over 600,000 Infantry, 30,000 Cavalry, 8,000 War-Chariots and 9,000 War Elephants not including tributary state allies.[1][2][3][4] In the Gupta age, large armies of longbowmen were recruited to fight off invading horse archer armies. Elephants, pikemen and cavalry were other featured troops.
+
+In Rajput times, the main piece of equipment was iron or chain-mail armour, a round shield, either a curved blade or a straight-sword, a chakra disc and a katar dagger.[citation needed]
+
+The states of China raised armies for at least 1000 years before the Spring and Autumn Annals[citation needed]. By the Warring States period, the crossbow had been perfected enough to become a military secret, with bronze bolts which could pierce any armor. Thus any political power of a state rested on the armies and their organization. China underwent political consolidation of the states of Han (韓), Wei (魏), Chu (楚), Yan (燕), Zhao (趙) and Qi (齊), until by 221 BCE, Qin Shi Huang (秦始皇帝), the first emperor of the Qin dynasty, attained absolute power. This first emperor of China could command the creation of a Terracotta Army to guard his tomb in the city of Xi'an (西安), as well as a realignment of the Great Wall of China to strengthen his empire against insurrection, invasion and incursion.
+
+Sun Tzu's The Art of War remains one of China's Seven Military Classics, even though it is two thousand years old.[5] Since no political figure could exist without an army, measures were taken to ensure only the most capable leaders could control the armies.[6] Civil bureaucracies (士大夫) arose to control the productive power of the states, and their military power.[7]
+
+The Spartan Army was one of the earliest known professional armies. Boys were sent to a barracks at the age of seven or eight to train for becoming a soldier. At the age of thirty they were released from the barracks and allowed to marry and have a family. After that, men devoted their lives to war until their retirement at the age of 60. Unlike other civilizations, whose armies had to disband during the planting and harvest seasons, the Spartan serfs or helots, did the manual labor.
+
+This allowed the Spartans to field a full-time army with a campaign season that lasted all year.[citation needed] The Spartan Army was largely composed of hoplites, equipped with arms and armor nearly identical to each other. Each hoplite bore the Spartan emblem and a scarlet uniform. The main pieces of this armor were a round shield, a spear and a helmet.
+
+The Roman Army had its origins in the citizen army of the Republic, which was staffed by citizens serving mandatory duty for Rome. Reforms turned the army into a professional organization which was still largely filled by citizens, but these citizens served continuously for 25 years before being discharged.[8]
+
+The Romans were also noted for making use of auxiliary troops, non-Romans who served with the legions and filled roles that the traditional Roman military could not fill effectively, such as light skirmish troops and heavy cavalry. After their service in the army they were made citizens of Rome and then their children were citizens also. They were also given land and money to settle in Rome. In the Late Roman Empire, these auxiliary troops, along with foreign mercenaries, became the core of the Roman Army; moreover, by the time of the Late Roman Empire tribes such as the Visigoths were paid to serve as mercenaries.
+
+In the earliest Middle Ages it was the obligation of every aristocrat to respond to the call to battle with his own equipment, archers, and infantry. This decentralized system was necessary due to the social order of the time, but could lead to motley forces with variable training, equipment and abilities. The more resources the noble had access to, the better his troops would be.
+
+Initially, the words "knight" and "noble" were used interchangeably as there was not generally a distinction between them. While the nobility did fight upon horseback, they were also supported by lower class citizens – and mercenaries and criminals – whose only purpose was participating in warfare because, most often than not, they held brief employment during their lord's engagement.[9] As the Middle Ages progressed and feudalism developed in a legitimate social and economic system, knights started to develop into their own class with a minor caveat: they were still in debt to their lord. No longer primarily driven by economic need, the newly established vassal class were, instead, driven by fealty and chivalry.
+
+As central governments grew in power, a return to the citizen armies of the classical period also began, as central levies of the peasantry began to be the central recruiting tool. England was one of the most centralized states in the Middle Ages, and the armies that fought in the Hundred Years' War were, predominantly, composed of paid professionals.
+
+In theory, every Englishman had an obligation to serve for forty days. Forty days was not long enough for a campaign, especially one on the continent.[10]
+
+Thus the scutage was introduced, whereby most Englishmen paid to escape their service and this money was used to create a permanent army. However, almost all high medieval armies in Europe were composed of a great deal of paid core troops, and there was a large mercenary market in Europe from at least the early 12th century.
+
+As the Middle Ages progressed in Italy, Italian cities began to rely mostly on mercenaries to do their fighting rather than the militias that had dominated the early and high medieval period in this region. These would be groups of career soldiers who would be paid a set rate. Mercenaries tended to be effective soldiers, especially in combination with standing forces, but in Italy they came to dominate the armies of the city states. This made them considerably less reliable than a standing army. Mercenary-on-mercenary warfare in Italy also led to relatively bloodless campaigns which relied as much on maneuver as on battles.
+
+In 1439 the French legislature, known as the  Estates General (French: états généraux), passed laws that restricted military recruitment and training to the king alone. There was a new tax to be raised known as the taille that was to provide funding for a new Royal army. The mercenary companies were given a choice of either joining the Royal army as compagnies d'ordonnance on a permanent basis, or being hunted down and destroyed if they refused. France gained a total standing army of around 6,000 men, which was sent out to gradually eliminate the remaining mercenaries who insisted on operating on their own. The new standing army had a more disciplined and professional approach to warfare than its predecessors. The reforms of the 1440s,  eventually led to the French victory at Castillon in 1453, and the conclusion of the Hundred Years' War. By 1450 the companies were divided into the field army, known as the grande ordonnance and the garrison force known as the petite ordonnance.[11]
+
+First nation states lacked the funds needed to maintain standing forces, so they tended to hire mercenaries to serve in their armies during wartime. Such mercenaries typically formed at the ends of periods of conflict, when men-at-arms were no longer needed by their respective governments.
+
+The veteran soldiers thus looked for other forms of employment, often becoming mercenaries. Free Companies would often specialize in forms of combat that required longer periods of training that was not available in the form of a mobilized militia.
+
+As late as the 1650s, most troops were mercenaries. However, after the 17th century, most states invested in better disciplined and more politically reliable permanent troops. For a time mercenaries became important as trainers and administrators, but soon these tasks were also taken by the state. The massive size of these armies required a large supporting force of administrators.
+
+The newly centralized states were forced to set up vast organized bureaucracies to manage these armies, which some historians argue is the basis of the modern bureaucratic state. The combination of increased taxes and increased centralisation of government functions caused a series of revolts across Europe such as the Fronde in France and the English Civil War.
+
+In many countries, the resolution of this conflict was the rise of absolute monarchy. Only in England and the Netherlands did representative government evolve as an alternative. From the late 17th century, states learned how to finance wars through long term low interest loans from national banking institutions. The first state to master this process was the Dutch Republic. This transformation in the armies of Europe had great social impact. The defense of the state now rested on the commoners, not on the aristocrats.
+
+However, aristocrats continued to monopolise the officer corps of almost all early modern armies, including their high command. Moreover, popular revolts almost always failed unless they had the support and patronage of the noble or gentry classes. The new armies, because of their vast expense, were also dependent on taxation and the commercial classes who also began to demand a greater role in society. The great commercial powers of the Dutch and English matched much larger states in military might.
+
+As any man could be quickly trained in the use of a musket, it became far easier to form massive armies. The inaccuracy of the weapons necessitated large groups of massed soldiers. This led to a rapid swelling of the size of armies. For the first time huge masses of the population could enter combat, rather than just the highly skilled professionals.
+
+It has been argued that the drawing of men from across the nation into an organized corps helped breed national unity and patriotism, and during this period the modern notion of the nation state was born. However, this would only become apparent after the French Revolutionary Wars. At this time, the levée en masse and conscription would become the defining paradigm of modern warfare.
+
+Before then, however, most national armies were in fact composed of many nationalities. In Spain armies were recruited from all the Spanish European territories including Spain, Italy, Wallonia (Walloon Guards) and Germany. The French recruited some soldiers from Germany, Switzerland as well as from Piedmont. Britain recruited Hessian and Hanovrian troops until the late 18th century. Irish Catholics made careers for themselves in the armies of many Catholic European states.
+
+Prior to the English Civil War in England, the monarch maintained a personal bodyguard of Yeomen of the Guard and the Honourable Corps of Gentlemen at Arms, or "gentlemen pensioners", and a few locally raised companies to garrison important places such as Berwick on Tweed or Portsmouth (or Calais before it was recaptured by France in 1558).
+
+Troops for foreign expeditions were raised upon an ad hoc basis. Noblemen and professional regular soldiers were commissioned by the monarch to supply troops, raising their quotas by indenture from a variety of sources. On January 26, 1661 Charles II issued the Royal Warrant that created the genesis of what would become the British Army, although the Scottish and English Armies would remain two separate organizations until the unification of England and Scotland in 1707. The small force was represented by only a few regiments.
+
+After the American Revolutionary War the Continental Army was quickly disbanded as part of the Americans' distrust of standing armies, and irregular state militias became the sole ground army of the United States, with the exception of one battery of artillery guarding West Point's arsenal. Then First American Regiment was established in 1784. However, because of continuing conflict with Native Americans, it was soon realized that it was necessary to field a trained standing army. The first of these, the Legion of the United States, was established in 1791.
+
+Until 1733 the common soldiers of Prussian Army consisted largely of peasantry recruited or impressed from Brandenburg–Prussia, leading many to flee to neighboring countries.[13] To halt this trend, Frederick William I divided Prussia into regimental cantons. Every youth was required to serve as a soldier in these recruitment districts for three months each year; this met agrarian needs and added extra troops to bolster the regular ranks.[14]
+
+Russian tsars before Peter I of Russia maintained professional hereditary musketeer corps (streltsy in Russian) that were highly unreliable and undisciplined. In times of war the armed forces were augmented by peasants. Peter I introduced a modern regular army built on German model, but with a new aspect: officers not necessarily from nobility, as talented commoners were given promotions that eventually included a noble title at the attainment of an officer's rank. Conscription of peasants and townspeople was based on quota system, per settlement. Initially it was based on the number of households, later it was based on the population numbers.[16] The term of service in the 18th century was for life. In 1793 it was reduced to 25 years. In 1834 it was reduced to 20 years plus 5 years in reserve and in 1855 to 12 years plus 3 years of reserve.[16][chronology citation needed]
+
+The first Ottoman standing army were Janissaries. They replaced forces that mostly comprised tribal warriors (ghazis) whose loyalty and morale could not always be trusted. The first Janissary units were formed from prisoners of war and slaves, probably as a result of the sultan taking his traditional one-fifth share of his army's booty in kind rather than cash.
+
+From the 1380s onwards, their ranks were filled under the devşirme system, where feudal dues were paid by service to the sultan. The "recruits" were mostly Christian youths, reminiscent of mamluks.
+
+China organized the Manchu people into the Eight Banner system in the early 17th century. Defected Ming armies formed the Green Standard Army. These troops enlisted voluntarily and for long terms of service.
+
+Conscription allowed the French Republic to form the Grande Armée, what Napoleon Bonaparte called "the nation in arms", which successfully battled European professional armies.
+
+Conscription, particularly when the conscripts are being sent to foreign wars that do not directly affect the security of the nation, has historically been highly politically contentious in democracies.
+
+Canada also had a political dispute over conscription during World War II. Similarly, mass protests against conscription to fight the Vietnam War occurred in several countries in the late 1960s.
+
+In developed nations, the increasing emphasis on technological firepower and better-trained fighting forces, the sheer unlikelihood of a conventional military assault on most developed nations, as well as memories of the contentiousness of the Vietnam War experience, make mass conscription unlikely in the foreseeable future.
+
+Russia, as well as many other nations, retains mainly a conscript army. There is also a very rare citizen army as used in Switzerland (see Military of Switzerland).
+
+Western armies are usually subdivided as follows:
+
+A field army is composed of a headquarters, army troops, a variable number of corps, typically between three and four, and a variable number of divisions, also between three and four. A battle is influenced at the Field Army level by transferring divisions and reinforcements from one corps to another to increase the pressure on the enemy at a critical point. Field armies are controlled by a general or lieutenant general.
+
+A particular army can be named or numbered to distinguish it from military land forces in general. For example, the First United States Army and the Army of Northern Virginia. In the British Army it is normal to spell out the ordinal number of an army (e.g. First Army), whereas lower formations use figures (e.g. 1st Division).
+
+Armies (as well as army groups and theaters) are large formations which vary significantly between armed forces in size, composition, and scope of responsibility.
+
+In the Soviet Red Army and the Soviet Air Force, "Armies" could vary in size, but were subordinate to an Army Group-sized "front" in wartime. In peacetime, a Soviet army was usually subordinate to a military district. Viktor Suvorov's Inside the Soviet Army describes how Cold War era Soviet military districts were actually composed of a front headquarters and a military district headquarters co-located for administration and deception ('maskirovika') reasons.

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+
+
+The Adriatic Sea /ˌeɪdriˈætɪk/ is a body of water separating the Italian Peninsula from the Balkans. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto (where it connects to the Ionian Sea) to the northwest and the Po Valley. The countries with coasts on the Adriatic are Albania, Bosnia and Herzegovina, Croatia, Italy, Montenegro and Slovenia. The Adriatic contains over 1,300 islands, mostly located along the Croatian part of its eastern coast. It is divided into three basins, the northern being the shallowest and the southern being the deepest, with a maximum depth of 1,233 metres (4,045 ft). The Otranto Sill, an underwater ridge, is located at the border between the Adriatic and Ionian Seas. The prevailing currents flow counterclockwise from the Strait of Otranto, along the eastern coast and back to the strait along the western (Italian) coast. Tidal movements in the Adriatic are slight, although larger amplitudes are known to occur occasionally. The Adriatic's salinity is lower than the Mediterranean's because the Adriatic collects a third of the fresh water flowing into the Mediterranean, acting as a dilution basin. The surface water temperatures generally range from 30 °C (86 °F) in summer to 12 °C (54 °F) in winter, significantly moderating the Adriatic Basin's climate.
+
+The Adriatic Sea sits on the Apulian or Adriatic Microplate, which separated from the African Plate in the Mesozoic era. The plate's movement contributed to the formation of the surrounding mountain chains and Apennine tectonic uplift after its collision with the Eurasian plate. In the Late Oligocene, the Apennine Peninsula first formed, separating the Adriatic Basin from the rest of the Mediterranean. All types of sediment are found in the Adriatic, with the bulk of the material transported by the Po and other rivers on the western coast. The western coast is alluvial or terraced, while the eastern coast is highly indented with pronounced karstification. There are dozens of marine protected areas in the Adriatic, designed to protect the sea's karst habitats and biodiversity. The sea is abundant in flora and fauna—more than 7,000 species are identified as native to the Adriatic, many of them endemic, rare and threatened ones.
+
+The Adriatic's shores are populated by more than 3.5 million people; the largest cities are Bari, Venice, Trieste and Split. The earliest settlements on the Adriatic shores were Etruscan, Illyrian, and Greek. By the 2nd century BC, the shores were under Rome's control. In the Middle Ages, the Adriatic shores and the sea itself were controlled, to a varying extent, by a series of states—most notably the Byzantine Empire, the Croatian Kingdom, the Republic of Venice, the Habsburg Monarchy and the Ottoman Empire. The Napoleonic Wars resulted in the First French Empire gaining coastal control and the British effort to counter the French in the area, ultimately securing most of the eastern Adriatic shore and the Po Valley for Austria. Following Italian unification, the Kingdom of Italy started an eastward expansion that lasted until the 20th century. Following World War I and the collapse of Austria-Hungary and the Ottoman Empire, the eastern coast's control passed to Yugoslavia and Albania. The former disintegrated during the 1990s, resulting in four new states on the Adriatic coast. Italy and Yugoslavia agreed on their maritime boundaries by 1975 and this boundary is recognised by Yugoslavia's successor states, but the maritime boundaries between Slovenia, Croatia, Bosnia-Herzegovina, and Montenegro are still disputed. Italy and Albania agreed on their maritime boundary in 1992.
+
+Fisheries and tourism are significant sources of income all along the Adriatic coast. Adriatic Croatia's tourism industry has grown faster economically than the rest of the Adriatic Basin's. Maritime transport is also a significant branch of the area's economy—there are 19 seaports in the Adriatic that each handle more than a million tonnes of cargo per year. The largest Adriatic seaport by annual cargo turnover is the Port of Trieste, while the Port of Split is the largest Adriatic seaport by passengers served per year.
+
+The origins of the name Adriatic are linked to the Etruscan settlement of Adria, which probably derives its name from the Illyrian adur meaning water or sea.[2] In classical antiquity, the sea was known as Mare Adriaticum (Mare Hadriaticum, also sometimes simplified to Adria) or, less frequently, as Mare Superum, "[the] upper sea".[3] The two terms were not synonymous, however. Mare Adriaticum generally corresponds to the Adriatic Sea's extent, spanning from the Gulf of Venice to the Strait of Otranto. That boundary became more consistently defined by Roman authors – early Greek sources place the boundary between the Adriatic and Ionian seas at various places ranging from adjacent to the Gulf of Venice to the southern tip of the Peloponnese, eastern shores of Sicily and western shores of Crete.[4] Mare Superum on the other hand normally encompassed both the modern Adriatic Sea and the sea off the Apennine peninsula's southern coast, as far as the Strait of Sicily.[5] Another name used in the period was Mare Dalmaticum, applied to waters off the coast of Dalmatia or Illyricum.[6]
+
+The names for the sea in the languages of the surrounding countries include Albanian: Deti Adriatik; Emilian: Mèr Adriatic; Friulian: Mâr Adriatic; Greek: Αδριατική θάλασσα – Adriatikí thálassa; Istro Romanian: Marea Adriatică; Italian: Mare Adriatico; Serbo-Croatian: Jadransko more, Јадранско море; Slovene: Jadransko morje; Venetian: Mar Adriàtico. In Serbo-Croatian and Slovene, the sea is often referred to as simply Jadran.
+
+The Adriatic Sea is a semi-enclosed sea,[7] bordered in the southwest by the Apennine or Italian Peninsula, in the northwest by the Italian regions of Veneto and Friuli-Venezia Giulia, and in the northeast by Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, and Albania—the Balkan peninsula. In the southeast, the Adriatic Sea connects to the Ionian Sea at the 72-kilometre (45 mi) wide Strait of Otranto.[8] The International Hydrographic Organization (IHO) defines the boundary between the Adriatic and the Ionian seas as a line running from the Butrinto River's mouth (latitude 39°44'N) in Albania to the Karagol Cape in Corfu, through this island to the Kephali Cape (these two capes are in latitude 39°45'N), and on to the Santa Maria di Leuca Cape (latitude 39°48'N).[9] It extends 800 kilometres (500 mi) from the northwest to the southeast and is 200 kilometres (120 mi) wide. It covers 138,600 square kilometres (53,500 sq mi) and has a volume of 35,000 cubic kilometres (8,400 cu mi). The Adriatic extends northwest from 40° to 45°47' north, representing the Mediterranean's northernmost portion.[8] The sea is geographically divided into the Northern Adriatic, Central (or Middle) Adriatic, and Southern Adriatic.[10] The Adriatic Sea drainage basin encompasses 235,000 square kilometres (91,000 sq mi), yielding a land–sea ratio of 1.8. The drainage basin's mean elevation is 782 metres (2,566 ft) above sea level, with a mean slope of 12.1°.[11] Major rivers discharging into the Adriatic include the Po, Soča, Krka, Neretva, Drin, Bojana, and Vjosë.[12][13] In the late 19th century, Austria-Hungary established a geodetic network with an elevation benchmark using the average Adriatic Sea level at the Sartorio pier in Trieste, Italy. The benchmark was subsequently retained by Austria, adopted by Yugoslavia, and retained by the states that emerged after its dissolution.[14][15] In 2016, Slovenia adopted a new elevation benchmark referring to the upgraded tide gauge station in the coastal town of Koper.[16]
+
+The Adriatic Sea contains more than 1,300 islands and islets, most along the Adriatic's eastern coast—especially in Croatia, with 1,246 counted.[20] The number includes islands, islets, and rocks of all sizes, including ones emerging at ebb tide only.[21] The Croatian islands include the largest—Cres and Krk, each covering about the same area of 405.78 square kilometres (156.67 sq mi)—and the tallest—Brač, whose peak reaches 780 metres (2,560 ft) above sea level. The islands of Cres and the adjacent Lošinj are separated only by a narrow navigable canal dug in the time of classical antiquity;[22] the original single island was known to the Greeks as Apsyrtides.[23] The Croatian islands include 47 permanently inhabited ones, the most populous among them being Krk, Korčula and Brač.[24] The islands along the Adriatic's western (Italian) coast are smaller and less numerous than those along the opposite coast; the best-known ones are the 117 islands on which the city of Venice is built.[25] The northern shore of the Greek island of Corfu also lies in the Adriatic Sea as defined by the IHO.[26] The IHO boundary places the Diapontia Islands (northwest of Corfu) in the Adriatic Sea.[9][27]
+
+The Adriatic Sea's average depth is 259.5 metres (851 ft), and its maximum depth is 1,233 metres (4,045 ft); however, the North Adriatic basin rarely exceeds a depth of 100 metres (330 ft).[17] The North Adriatic basin, extending between Venice and Trieste towards a line connecting Ancona and Zadar, is only 15 metres (49 ft) deep at its northwestern end; it gradually deepens towards the southeast. It is the largest Mediterranean shelf and is simultaneously a dilution basin and a site of bottom water formation.[28] The Middle Adriatic basin is south of the Ancona–Zadar line, with the 270-metre (890 ft) deep Middle Adriatic Pit (also called the Pomo Depression or the Jabuka Pit). The 170-metre (560 ft) deep Palagruža Sill is south of the Middle Adriatic Pit, separating it from the 1,200-metre (3,900 ft) deep South Adriatic Pit and the Middle Adriatic basin from the South Adriatic Basin. Further on to the south, the sea floor rises to 780 metres (2,560 ft) to form the Otranto Sill at the boundary to the Ionian Sea. The South Adriatic Basin is similar in many respects to the Northern Ionian Sea, to which it is connected.[13] Transversely, the Adriatic Sea is also asymmetric: the Apennine peninsular coast is relatively smooth with very few islands and the Monte Conero and Gargano promontories as the only significant protrusions into the sea; in contrast, the Balkan peninsular coast is rugged with numerous islands, especially in Croatia. The coast's ruggedness is exacerbated by the Dinaric Alps' proximity to the coast, in contrast to the opposite (Italian) coast where the Apennine Mountains are further away from the shoreline.[29]
+
+The coastal water dynamics are determined by the asymmetric coasts and the inflow of the Mediterranean seawater through the Straits of Otranto and further on along the eastern coast.[30] The smooth Italian coast (with very few protrusions and no major islands) allows the Western Adriatic Current to flow smoothly, which is composed of the relatively freshwater mass on the surface and the cold and dense water mass at the bottom.[31] The coastal currents on the opposite shore are far more complex owing to the jagged shoreline, several large islands and the proximity of the Dinaric Alps to the shore. The last produces significant temperature variations between the sea and the hinterland, which leads to the creation of local jets.[29] The tidal movement is normally slight, usually remaining below 30 centimetres (12 in). The amphidromic point is at the mid-width east of Ancona.[32]
+
+The normal tide levels are known to increase significantly in a conducive environment, leading to coastal flooding; this phenomenon is most famously known in Italy—especially Venice—as acqua alta. Such tides can exceed normal levels by more than 140 centimetres (55 in),[33] with the highest tide level of 194 centimetres (76 in) observed on 4 November 1966.[34] Such flooding is caused by a combination of factors, including the alignment of the Sun and Moon, meteorological factors such as sirocco related storm surges,[35] and the basin's geometric shape (which amplifies or reduces the astronomical component). Moreover, the Adriatic's long and narrow rectangular shape is the source of an oscillating water motion (French: seiche) along the basin's minor axis.[36] Finally, Venice is increasingly vulnerable to flooding due to coastal area soil subsidence.[37] Such unusually high tides resulting in flooding have also been observed elsewhere in the Adriatic Sea, and have been recorded in recent years in the towns of Koper, Zadar and Šibenik as well.[38][39][40]
+
+It is estimated that the Adriatic's entire volume is exchanged through the Strait of Otranto in 3.4±0.4 years, a comparatively short period. (For instance, approximately 500 years are necessary to exchange all the Black Sea's water.) This short period is particularly important as the rivers flowing into the Adriatic discharge up to 5,700 cubic metres per second (200,000 cu ft/s). This rate of discharge amounts to 0.5% of the total Adriatic Sea volume, or a 1.3-metre (4 ft 3 in) layer of water each year. The greatest portion of the discharge from any single river comes from the Po (28%),[41] with an average discharge from it alone of 1,569 cubic metres per second (55,400 cu ft/s).[42] In terms of the annual total discharge into the entire Mediterranean Sea, the Po is ranked second, followed by the Neretva and Drin, which rank as third and fourth.[43] Another significant contributor of freshwater to the Adriatic is the submarine groundwater discharge through submarine springs (Croatian: vrulja); it is estimated to comprise 29% of the total water flux into the Adriatic.[44] The submarine springs include thermal springs, discovered offshore near the town of Izola. The thermal springwater is rich with hydrogen sulfide, has a temperature of 22 to 29.6 °C (71.6 to 85.3 °F), and has enabled the development of specific ecosystems.[45] The inflow of freshwater, representing a third of the freshwater volume flowing into the Mediterranean,[13] makes the Adriatic a dilution basin for the Mediterranean Sea.[46] The Middle and South Adriatic Gyres (SAG), are significant cyclonic circulation features, with the former being intermittent and the latter permanent. The SAG measures 150 kilometres (93 miles) in diameter. It contributes to the flow of bottom water from the Adriatic to the Levantine Basin through the Ionian Sea. Through that process, the Adriatic Sea produces most of the East Mediterranean deep water.[47]
+
+The Adriatic's surface temperature usually ranges from 22 to 30 °C (72 to 86 °F) in the summer, or 12 to 14 °C (54 to 57 °F) in the winter, except along the western Adriatic coast's northern part, where it drops to 9 °C (48 °F) in the winter. The distinct seasonal temperature variations, with a longitudinal gradient in the Northern and transversal gradient in the Middle and Southern Adriatic,[48] are attributed to the continental characteristics of the Adriatic Sea: it is shallower and closer to land than are oceans.[49] During particularly cold winters, sea ice may appear in the Adriatic's shallow coastal areas, especially in the Venetian Lagoon but also in isolated shallows as far south as Tisno (south of Zadar).[50][51] The Southern Adriatic is about 8 to 10 °C (14 to 18 °F) warmer during the winter than the more northerly regions.[52] The Adriatic's salinity variation over the year is likewise distinct:[49] it ranges between 38 and 39 PSUs.[48] The southern Adriatic is subjected to saltier water from the Levantine Basin.[52]
+
+According to the Köppen climate classification, the upper half of the Adriatic is classified as humid subtropical climate (Cfa), with wetter summers and colder and drier winters, and the southern Adriatic are classified as hot-summer Mediterranean climate (Csa).[53][54] The air temperature can fluctuate by about 20 °C (36 °F) during a season.[48]
+
+The predominant winter winds are the bora and sirocco (called jugo along the eastern coast). The bora is significantly conditioned by wind gaps in the Dinaric Alps bringing cold and dry continental air; it reaches peak speeds in the areas of Trieste, Senj, and Split, with gusts of up to 180 kilometres per hour (97 kn; 110 mph). The sirocco brings humid and warm air, often carrying Saharan sand causing rain dust.[55]
+
+Bari
+Venice
+
+Trieste
+Durrës
+
+On the Adriatic Sea's coasts and islands, there are numerous small settlements, and a number of larger cities. Among the largest are Bari, Venice, Trieste, and Rimini in Italy, Split, Rijeka and Zadar in Croatia, Durrës and Vlorë in Albania and Koper in Slovenia. In total, more than 3.5 million people live on the Adriatic coasts.[61] There are also some larger cities that are located very near the coast, such as the Italian cities of Ravenna and Lecce.
+
+Venice, which was originally built on islands off the coast, is most at risk due to subsidence, but the threat is present in the Po delta as well. The causes are a decrease in sedimentation rate due to loss of sediment behind dams, the deliberate excavation of sand for industrial purposes, agricultural use of water, and removal of ground water.[62][63]
+
+The sinking of Venice slowed after artesian wells were banned in the 1960s, but the city remains threatened by the acqua alta floods. Recent studies have suggested that the city is no longer sinking,[64][65] but a state of alert remains in place. In May 2003, then-Prime Minister Silvio Berlusconi inaugurated the MOSE project (Italian: Modulo Sperimentale Elettromeccanico), an experimental model for evaluating the performance of inflatable gates. The project proposes laying a series of 79 inflatable pontoons across the sea bed at the three entrances to the Venetian Lagoon. When tides are predicted to rise above 110 centimetres (43 in), the pontoons will be filled with air and block the incoming water from the Adriatic Sea. This engineering work is due to be completed by 2014.[66][needs update]
+
+Geophysical and geological information indicate that the Adriatic Sea and the Po Valley are associated with a tectonic microplate—identified as the Apulian or Adriatic Plate—that separated from the African Plate during the Mesozoic era. This separation began in the Middle and Late Triassic, when limestone began to be deposited in the area. Between the Norian and Late Cretaceous, the Adriatic and Apulia Carbonate Platforms formed as a thick series of carbonate sediments (dolomites and limestones), up to 8,000 metres (26,000 ft) deep.[67] Remnants of the former are found in the Adriatic Sea, as well as in the southern Alps and the Dinaric Alps, and remnants of the latter are seen as the Gargano Promontory and the Maiella mountain. In the Eocene and early Oligocene, the plate moved north and north-east, contributing to the Alpine orogeny (along with the African and Eurasian Plates' movements) via the tectonic uplift of the Dinarides and Alps. In the Late Oligocene, the motion was reversed and the Apennine Mountains' orogeny took place.[68] An unbroken zone of increased seismic activity borders the Adriatic Sea, with a belt of thrust faults generally oriented in the northeast–southwest direction on the east coast and the northeast–southwest normal faults in the Apennines, indicating an Adriatic counterclockwise rotation.[69] An active 200-kilometre (120 mi) fault has been identified to the northwest of Dubrovnik, adding to the Dalmatian islands as the Eurasian Plate slides over the Adriatic microplate. Furthermore, the fault causes the Apennine peninsula's southern tip to move towards the opposite shore by about 0.4 centimetres (0.16 in) per year. If this movement continues, the seafloor will be completely consumed and the Adriatic Sea closed off in 50–70 million years.[70] In the Northern Adriatic, the coast of the Gulf of Trieste and western Istria is gradually subsiding, having sunk about 1.5 metres (4 ft 11 in) in the past two thousand years.[71] In the Middle Adriatic Basin, there is evidence of Permian volcanism in the area of Komiža on the island of Vis and the volcanic islands of Jabuka and Brusnik.[72] Earthquakes have been observed in the region since the earliest historical records.[73] A recent strong earthquake in the region was the 1979 Montenegro earthquake, measuring 7.0 on the Richter scale.[74] Historical earthquakes in the area include the 1627 Gargano peninsula and the 1667 Dubrovnik earthquakes, both followed by strong tsunamis.[75] In the last 600 years, fifteen tsunamis have occurred in the Adriatic Sea.[76]
+
+All types of seafloor sediments are found in the Adriatic Sea. The Northern Adriatic's comparatively shallow seabed is characterised by relict sand (from times when the water level was lower and the area was a sandy beach), while a muddy bed is typical at depths below 100 metres (330 ft).[30][77] There are five geomorphological units in the Adriatic: the Northern Adriatic (up to 100 metres (330 ft) deep); the North Adriatic islands area protected against sediments filling it in by outer islands (pre-Holocene karst relief); the Middle Adriatic islands area (large Dalmatian islands); the Middle Adriatic (characterized by the Middle Adriatic Depression); and the Southern Adriatic consisting of a coastal shelf and the Southern Adriatic Depression. Sediments deposited in the Adriatic Sea today generally come from the northwest coast, being carried by the Po, Reno, Adige, Brenta, Tagliamento, Piave and Soča rivers. The volume of sediments carried from the eastern shore by the Rječina, Zrmanja, Krka, Cetina, Ombla, Dragonja, Mirna, Raša and Neretva rivers is negligible, because these sediments are mostly deposited at the river mouths. The Adriatic's western shores are largely either alluvial or terraced, whereas the eastern shores are predominantly rocky, except for the southernmost part of the shore located in Albania that consists of sandy coves and rocky capes.[68]
+
+The eastern Adriatic shore's Croatian part is the most indented Mediterranean coastline.[78] Most of the eastern coast is characterised by a karst topography, developed from the Adriatic Carbonate Platform's exposure to weathering. Karstification there largely began after the Dinarides' final uplift in the Oligocene and the Miocene, when carbonate deposits were exposed to atmospheric effects; this extended to the level of 120 metres (390 ft) below the present sea level, exposed during the Last Glacial Maximum. It is estimated that some karst formations are from earlier sea level drops, most notably the Messinian salinity crisis.[67] Similarly, karst developed in Apulia from the Apulian Carbonate Platform.[79]
+
+The largest part of the eastern coast consists of carbonate rocks, while flysch (a particular type of sedimentary rock) is significantly represented in the Gulf of Trieste coast, especially along Slovenia's coast where the 80-metre (260 ft) Strunjan cliff—the highest cliff on the entire Adriatic and the only one of its type on the eastern Adriatic coast—is located,[80] on the Kvarner Gulf coast opposite Krk, and in Dalmatia north of Split.[81] Rocks of the same type are found in Albania and on the western Adriatic coast.[82][83]
+
+There are alternations of maritime and alluvial sediments occurring in the Po Valley, at the Adriatic's north-west coast, and as far west as Piacenza, dating to the Pleistocene as the sea advanced and receded over the valley. An advance began after the Last Glacial Maximum, which brought the Adriatic to a high point at about 5,500 years ago.[84] Since then, the Po delta has been prograding (expanding/extending). The rate of coastal zone progradation between 1000 BC and 1200 AD was 4 metres (13 ft) per year.[85] In the 12th century, the delta advanced at a rate of 25 metres (82 ft) per year. In the 17th century, the delta began to become a human-controlled environment, as the excavation of artificial channels started; the channels and new distributaries of the Po have been prograding at rates of 50 metres (160 ft) per year or more since then.[86] There are more than 20 other rivers flowing into the Adriatic Sea in Italy alone, also forming alluvial coastlines,[87] including the lagoons of Venice, Grado and Caorle.[88] There are smaller eastern Adriatic alluvial coasts—in the deltas of the Dragonja,[89] Bojana and Neretva rivers.[90][91]
+
+The Adriatic Sea is a unique water body in respect of its overall biogeochemical physiognomy. It exports inorganic nutrients and imports particulate organic carbon and nitrogen through the Strait of Otranto—acting as a mineralization site. The exchange of the substances is made more complex by bathymetry of the Adriatic Sea—75% of water flowing north through the strait recirculates at the Palagruža Sill and North Adriatic adds no more than 3 – 4% of water to the South Adriatic.[92] This is reflected in its biogeography and ecology, and particularly in the composition and properties of its ecosystems.[93] Its main biogeographic units are the Northern Adriatic, the Central Adriatic, and the Southern Adriatic.[94]
+
+The unique nature of the Adriatic gives rise to an abundance of endemic flora and fauna. The Croatian National Biodiversity Strategy Action Plan identified more than 7,000 animal and plant species in the Adriatic Sea. The Central Adriatic is especially abundant in endemic plant species, with 535 identified species of green, brown and red algae.[95] Four out of five Mediterranean seagrass species are found in the Adriatic Sea. The most common species are Cymodocea nodosa and Zostera noltii, while Zostera marina and Posidonia oceanica are comparatively rare.[96]
+
+A number of rare and threatened species are also found along the Adriatic's eastern coast; it is relatively clearer and less polluted than the western Adriatic coast—in part because the sea currents flow through the Adriatic in a counterclockwise direction, thus bringing clearer waters up the eastern coast and returning increasingly polluted water down the western coast. This circulation has significantly contributed to the biodiversity of the countries along the eastern Adriatic coast; the common bottlenose dolphin is frequent in the eastern coast's waters only, and the Croatian coast provides refuge for the critically endangered monk seal and sea turtles.[95] Recent studies revealed that cetaceans and other marine megafaunas, that were once thought to be vagrants to Adriatic Sea, migrate and live in the semi-closed sea on larger scales.[97] Largest of these live normally is the fin whale,[98] and sperm whale,[99] the largest of toothed whales also migrate but less common than fin whales, followed by Cuvier's beaked whales.[97] Basking sharks[100] and manta rays are some of migrant species to the sea.[101][102][103] Historical presences of depleted or extinct species such as North Atlantic right whales (extinct or functionally extinct), atlantic gray whales (extinct), and humpback whales have been speculated as well.[104]
+
+The Northern Adriatic in particular is rich in endemic fish fauna.[13] Around thirty species of fish are found in only one or two countries bordering the Adriatic Sea. These are particularly due to or dependent upon the karst morphology of the coastal or submarine topography; this includes inhabiting subterranean habitats, karst rivers, and areas around freshwater springs.[105] There are 45 known subspecies endemic to the Adriatic's coasts and islands. In the Adriatic, there are at least 410 species and subspecies of fish, representing approximately 70% of Mediterranean taxa, with at least 7 species endemic to the Adriatic. Sixty-four known species are threatened with extinction, largely because of overfishing.[95] Only a small fraction of the fish found in the Adriatic are attributed to recent processes such as Lessepsian migration, and escape from mariculture.[106]
+
+The biodiversity of the Adriatic is relatively high, and several marine protected areas have been established by countries along its coasts. In Italy, these are Miramare in the Gulf of Trieste (in the Northern Adriatic), Torre del Cerrano and Isole Tremiti in the Middle Adriatic basin and Torre Guaceto in southern Apulia.[107][108] The Miramare protected area was established in 1986 and covers 30 hectares (74 acres) of coast and 90 hectares (220 acres) of sea. The area encompasses 1.8 kilometres (1.1 mi) of coastline near the Miramare promontory in the Gulf of Trieste.[109] The Torre del Cerrano protected area was created in 2009, extending 3 nautical miles (5.6 km; 3.5 mi) into the sea and along 7 kilometres (4.3 mi) of coastline. Various zones of the protected area cover 37 square kilometres (14 sq mi) of sea surface.[110] The Isole Tremiti reserve has been protected since 1989, while the Tremiti islands themselves are part of the Gargano National Park.[111] The Torre Guaceto protected area, located near Brindisi and Carovigno, covers a sea surface of 2,227 hectares (5,500 acres) and is adjacent to the Torre Guaceto State Reserve covering 1,114 hectares (2,750 acres) of coast and sharing an 8-kilometre (5.0 mi) coastline with the marine protected area.[112] Furthermore, there are 10 internationally important (Ramsar) wetland reserves in Italy located along the Adriatic coast.[113]
+
+There are seven marine protected areas in Croatia: Brijuni and the Lim Canal off the Istria peninsula's coast, near Pula and Rovinj respectively; Kornati and Telašćica in the Middle Adriatic basin, near Zadar; and Lastovo, Bay of Mali Ston (Croatian: Malostonski zaljev) and Mljet in southern Dalmatia.[107] The Brijuni national park encompasses the 743.3-hectare (1,837-acre) archipelago itself and 2,651.7 hectares (6,552 acres) of surrounding sea;[114] it became a national park in 1999.[115] The Lim Canal is a 10-kilometre (6.2 mi) ria of the Pazinčica river.[116] The Kornati national park was established in 1980; it covers approximately 220 square kilometres (85 sq mi), including 89 islands and islets. The marine environment encompasses three-quarters of the total area, while the island shores' combined length equals 238 kilometres (148 mi).[117] Telašćica is a nature park established on Dugi Otok in 1988. The park covers 69 kilometres (43 mi) of coastline, 22.95 square kilometres (8.86 sq mi) of land and 44.55 square kilometres (17.20 sq mi) of sea.[118] The Bay of Mali Ston is located at the border of Croatia and Bosnia–Herzegovina, north of the Pelješac peninsula. The marine protected area covers 48 square kilometres (19 sq mi).[107] The Lastovo nature park was established in 2006, and it includes 44 islands and islets, 53 square kilometres (20 sq mi) of land and 143 square kilometres (55 sq mi) of sea surface.[119] The Mljet national park was established in 1960, covering a 24-square-kilometre (9.3 sq mi) marine protection area.[107] In addition, there is a Ramsar wetland reserve in Croatia—the Neretva river's delta.[120]
+
+In Slovenia, the marine and coastal protected nature areas are the Sečovlje Salina Landscape Park, Strunjan Landscape Park, Škocjan Inlet Nature Reserve, and the Debeli Rtič, Cape Madona and Lakes in Fiesa natural monuments.[121][122] The Sečovlje Salina Landscape Park was established in 1990, covers 721 hectares (1,780 acres), and includes four nature reserves.[123][124] In 1993, the area was designated a Ramsar site;[121] it is also a site of international importance for waterbird species.[125] The 429-hectare (1,060-acre) Strunjan Landscape Park was established in 2004 and comprises two nature reserves.[121][123] It includes a 4 kilometres (2.5 mi) long cliff, the northernmost Mediterranean salt field and the only Slovenian lagoon system.[126] It is also the northernmost point of growth of some Mediterranean plant species.[127] The Škocjan Inlet Nature Reserve was established in 1998 and covers 122 hectares (300 acres).[128] The Debeli Rtič natural monument covers 24 hectares (59 acres),[129] the Cape Madona natural monument covers 12 hectares (30 acres),[130] and the Lakes in Fiesa natural monument, with the coastal lake as the only brackish lake in Slovenia,[131] covers 2.1 hectares (5.2 acres).[132]
+
+In 2010, Albania established its first marine protection area, the Karaburun-Sazan National Marine Park at the Karaburun Peninsula where the Adriatic and Ionian Seas meet. The park covers a total of 12,570 hectares (31,100 acres).[133] Two additional marine protection areas are planned in Albania: the Cape of Rodon (Albanian: Kepi i Rodonit) and Porto Palermo.[107] In addition, Albania is home to two Ramsar wetland reserves: Karavasta Lagoon, and Butrint.[134] Neither Bosnia–Herzegovina nor Montenegro have or plan to establish any marine protection areas.[107]
+
+The Adriatic Sea ecosystem is threatened by excessive input of nutrients through drainage from agricultural land and wastewater flowing from cities; this includes both along its coast and from rivers draining into the sea—especially from the Po River.[135] Venice is often cited as an example of polluted coastal waters where shipping, transportation, farming, manufacturing and wastewater disposal contribute to polluting the sea.[136] A further risk is presented by ballast water discharge by ships, especially tankers. Still, since most of the cargo handled by the Adriatic ports, and virtually all liquid (tanker) cargo handled by the ports, is coming to—not coming from—the Adriatic Basin, the risk from ballast water (from tankers expelling ballast water then loading in the Adriatic) remains minimal. However, proposed export oil pipelines were objected to specifically because of this issue. Oil spills are a major concern in terms of potential environmental impact and damage to tourism and fisheries.[137] It is estimated that if a major oil spill happened, a million people would lose their livelihoods in Croatia alone.[138] An additional risk is presented by oil refineries in the Po River basin where oil spills have occurred before,[139] in addition to accidents occurring in the Adriatic already, so far with no significant environmental consequences.[140] Since 2006, Italy has been considering the construction of an offshore and an onshore LNG terminal in the Gulf of Trieste, as well as a pipeline, in the immediate vicinity of the Slovenian–Italian border.[141] The Slovenian government and municipalities,[142] the municipal council of Trieste,[143] and non-governmental organisations have voiced concern over their environmental hazards, effect on transport and effect on tourism.[144][145]
+
+Another source of pollution of the Adriatic is solid waste. Drifting waste—occasionally relatively large quantities of material, especially waste plastic—is transported northwest by the sirocco.[146] Air pollution in the Adriatic Basin is associated with the large industrial centres in the Po River valley and the large industrial cities along the coast.[147][148]
+
+Italy and Yugoslavia established a joint commission to protect the Adriatic Sea from pollution in 1977; the organization later changed with Slovenia, Croatia and Montenegro replacing Yugoslavia.[149] Future pollution hazards are addressed and pollution hotspots are assessed not only by nations in the basin but also through regional projects with World Bank support. 27 such hotspots have been determined as of 2011, 6 warranting an urgent response.[150]
+
+Settlements along the Adriatic dating to between 6100 and 5900 BC appear in Albania and Dalmatia on the eastern coast, related to the Cardium pottery culture.[151] During classical antiquity, Illyrians inhabited the eastern Adriatic coast,[152] and the western coast was inhabited by the peoples of Ancient Italy, mainly Etruscans, before the Roman Republic's rise.[153] Greek colonisation of the Adriatic dates back to the 7th and 6th centuries BC when Epidamnos and Apollonia were founded. The Greeks soon expanded further north establishing several cities, including Epidaurus, Black Corcyra, Issa and Ancona, with trade established as far north as the Po River delta, where the emporion (trading station) of Adria was founded.[154]
+
+Roman economic and military influence in the region began to grow with the creation by 246 BC of a major naval base at Brundisium (now Brindisi), which was established to bar Carthaginian ships from the Adriatic during the Punic Wars. This led to conflict with the Illyrians, who lived in a collection of semi-Hellenized kingdoms that covered much of the Balkans and controlled the eastern shore of the sea, resulting in the Illyrian Wars from 229–168 BC. The initial Roman intervention in 229 BC, motivated in part by a desire to suppress Illyrian piracy in the Adriatic, marked the first time that the Roman navy crossed that sea to launch a military campaign.[155][156] Those wars ended with the eastern shore becoming a province of the Roman Republic.[157] However, resistance to Roman rule continued sporadically and Rome did not completely consolidate control of the region until Augustus's general Tiberius put down the Great Illyrian Revolt, a bitter struggle waged from 6 to 9 AD.[156][158] Following the repression of the revolt the Roman province of Illyricum was split into Dalmatia and Pannonia. Most of the eastern shore of the Adriatic was part of Dalmatia, except for the southernmost portion, part of the province of Macedonia, and the peninsula of Istria on the northern part of the eastern shore; Istria contained the important Roman colony at Pula and was incorporated into the province of Italy.[159]
+
+During the Roman period Brundisium, on the western shore, and Apollonia and Dyrrachium (originally called Epidamnos, now Durrës in Albania) on the eastern shore became important ports. Brundisium was linked by the Via Appia road to the city of Rome, and Dyrrachium and Apollonia were both on the Via Egnatia, a road that by about 130 BC the Romans had extended eastward across the Balkans to Byzantium (later Constantinople, now Istanbul).[160][161] This made the sea passage across the Adriatic between Brundisium and Dyrrachium (or Apollonia) a link in the primary route for travelers, trade, and troop movements, between Rome and the East. This route played a major role in some of the military operations that marked the end of the Roman Republic and start of the imperial period. Sulla used it during the First Mithridatic War.[162] During Caesar's Civil War, there was a three-month delay in Caesar's Balkan campaign against Pompey caused when winter storms on the Adriatic and a naval blockade held up Mark Antony from reaching him from Brundisium with reinforcements; after the reinforcements finally arrived Caesar made an unsuccessful attempt to capture Dyrrachium before the campaign moved inland.[163]  Marc Antony and Octavian (later Augustus) crossed the Adriatic to Dyrrachium with their armies in their campaign against two of Caesar's assassins, Brutus and Cassius, that culminated in the Battle of Philippi.[164] Brundisium and Dyrrachium remained important ports well after the Roman period, but an earthquake in the 3rd century AD changed the path of a river causing Apollonia's harbor to silt up, and the city to decline.[165]
+
+Another city on the Italian coast of the Adriatic that increased in importance during the Roman era was Ravenna. During the reign of Augustus it became a major naval base as part of his program to re-organize the Roman navy to better protect commerce in the Mediterranean.[166] During the 4th century AD the emperors of the Western Roman Empire had moved their official residence north from Rome to Mediolanum (now Milan) in order to be better able to control the military frontier with the Germanic tribes. In 402 AD, during a period of repeated Germanic invasions of Italy, the capital was shifted to Ravenna because nearby marshes made it more defensible, and the Adriatic provided an easy escape path by sea.[167] When the Western Empire fell in 476 AD Ravenna became the capital of the Ostrogothic Kingdom of Italy.[168]
+
+In the Early Middle Ages, after the Roman Empire's decline, the Adriatic's coasts were ruled by Ostrogoths, Lombards and the Byzantine Empire.[169][170] The Ostrogothic Kingdom ruled Italy following the fall of the Western Roman Empire in 476 AD. However, during the reign of Justinian the Byzantine Empire sent an army under the general Belisarius to regain control of Italy, resulting in the Gothic War (535–554). The Byzantines established the Exarchate of Ravenna and by 553 AD their viceroy (Exarch) ruled almost the entire Italian peninsula from that city. In 568 AD the Lombards invaded northern Italy, and over the course of the next century or so the importance of the Exarchate declined as the territory under Lombard control expanded and as the Byzantine outpost of Venice became increasingly independent. In 752 AD the Lombards overthrew the Exarchate, ending the influence of the Byzantine Empire on the western shore of the Adriatic for a few centuries.[171]
+
+The last part of the period saw the rise of the Carolingian Empire and then the Frankish Kingdom of Italy, which controlled the Adriatic Sea's western coast,[172] while Byzantine Dalmatia on the east coast gradually shrunk following the Avar and Croatian invasions starting in the 7th century.[173] The Republic of Venice was founded during this period and went on to become a significant maritime power after receiving a Byzantine tax exemption in 1082.[174] The end of the period brought about the Holy Roman Empire's control over the Kingdom of Italy (which would last until the Peace of Westphalia in 1648),[175] the establishment of an independent Kingdom of Croatia and the Byzantine Empire's return to the southern Apennine peninsula.[176][177] In addition, the Papal States were carved out in the area around Rome and central Italy in the 8th century.[178]
+
+The High Middle Ages in the Adriatic Sea basin saw further territorial changes, including the Norman conquest of southern Italy ending the Byzantine presence on the Apennine peninsula in the 11th and 12th centuries (the territory would become the Kingdom of Naples in 1282)[179][180] and the control of a substantial part of the eastern Adriatic coast by the Kingdom of Hungary after a personal union was established between Croatia and Hungary in 1102.[181] In this period, the Republic of Venice began to expand its territory and influence.[182] In 1202, the Fourth Crusade was diverted to conquer Zadar at the behest of the Venetians—the first instance of a Crusader force attacking a Catholic city—before proceeding to sack Constantinople.[183] In the 13th century, Venice established itself as a leading maritime nation. During much of the 12th and 13th centuries, Venice and the Republic of Genoa were engaged in warfare culminating in the War of Chioggia, ousting the Genoese from the Adriatic.[184] Still, the 1381 Treaty of Turin that ended the war required Venice to renounce claims to Dalmatia, after losing the territory to Hungary in 1358. In the same year, the Republic of Ragusa was established in Dubrovnik as a city-state after it was freed from Venetian suzerainty.[185]
+
+Venice regained Dalmatia in 1409 and held it for nearly four hundred years, with the republic's apex of trading and military power in the first half of the 15th century.[186] The 15th and the 16th centuries brought about the Byzantine Empire's destruction in 1453 and the Ottoman Empire's expansion that reached Adriatic shores in present-day Albania and Montenegro as well as the immediate hinterland of the Dalmatian coast,[187][188] defeating the Hungarian and Croatian armies at Krbava in 1493 and Mohács in 1526.[189] These defeats spelled the end of an independent Hungarian kingdom, and both Croatian and Hungarian nobility chose Ferdinand I of the House of Habsburg as their new ruler, bringing the Habsburg Monarchy to the shore of the Adriatic Sea, where it would remain for nearly four hundred years.[190] The Ottomans and Venetians fought a series of wars, but until the 17th century these were not fought in the Adriatic area.[191] Ottoman raids on the Adriatic coasts effectively ceased after the massive setback in the Battle of Lepanto in October 1571.[192]
+
+In 1648, the Holy Roman Empire lost its claim on its former Italian lands, formally ending the Kingdom of Italy; however, its only outlet on the Adriatic Sea, the Duchy of Ferrara, was already lost to the Papal States.[193] The 17th century's final territorial changes were caused by the Morean or Sixth Ottoman–Venetian War, when in 1699 Venice slightly enlarged its possessions in Dalmatia.[194] In 1797, the Republic of Venice was abolished after the French conquest.[195] The Venetian territory was then handed over to Austria and briefly ruled as part of the Archduchy of Austria. The territory was turned back over to France after the Peace of Pressburg in 1805, when the territory in the Po valley became an integral part of the new Napoleonic Kingdom of Italy.[196] The new kingdom included the province of Romagna, thus removing the Papal State from the Adriatic coast;[197] however, Trieste, Istria and Dalmatia were joined into a set of separate provinces of the French Empire: the Illyrian Provinces.[196] These were created in 1809 through the Treaty of Schönbrunn; they represented the end of Venetian rule on the eastern Adriatic coast, as well as the end of the Republic of Ragusa.[198] The Adriatic Sea was a minor theatre in the Napoleonic Wars; the Adriatic campaign of 1807–1814 involved the British Royal Navy contesting the Adriatic's control by the combined navies of France, Italy and the Kingdom of Naples. During the campaign, the Royal Navy occupied Vis and established its base there in Port St. George.[199] The campaign reached its climax in the 1811 Battle of Lissa,[200] and ended with British and Austrian troops seizing the coastal cities on the eastern Adriatic coast from the French.[201] Days before the Battle of Waterloo, the Congress of Vienna awarded the Illyrian Provinces (spanning from the Gulf of Trieste to the Bay of Kotor) to Austria.[202] The Congress of Vienna also created the Kingdom of Lombardy–Venetia which encompassed the city of Venice, the surrounding coast and a substantial hinterland, and was controlled by Austria.[203] In the Apennine peninsula's south, the Kingdom of the Two Sicilies was formed in 1816 by unifying the kingdoms of Naples and Sicily.[204]
+
+The process of Italian unification culminated in the Second Italian War of Independence, resulting in the Kingdom of Sardinia annexing all territories along the western Adriatic coast south of Venetia in 1860, and the 1861 establishment of the Kingdom of Italy in its place. The Kingdom of Italy expanded in 1866: it annexed Venetia,[205] but its navy was defeated in the Adriatic near Vis.[206] Following the Austro-Hungarian Compromise of 1867 and the Croatian–Hungarian Settlement of 1868, the control of much of the eastern Adriatic coast was redefined. The cisleithanian (Austrian) part of Austria-Hungary spanned from the Austrian Littoral to the Bay of Kotor, with the exception of the Croatian Littoral mainland. In the territory outside the Austrian Littoral, special status was given to Fiume (modern day Rijeka) as a separate part of the Kingdom of Hungary. The rest of the territory was made a part of the Kingdom of Croatia-Slavonia, which in turn was also in the Transleithanian part of the dual monarchy.[181] The Adriatic coastline controlled by the Ottoman Empire was reduced by the Congress of Berlin in 1878, through recognition of the independence of the Principality of Montenegro, which controlled the coast south of the Bay of Kotor to the Bojana River.[207] The Ottoman Empire lost all territories along the Adriatic following the First Balkan War and consequent 1913 Treaty of London that established an independent Albania.[208]
+
+The World War I Adriatic Campaign was largely limited to blockade attempts by the Allies and the effort of the Central Powers to thwart the British, French and Italian moves.[209] Italy joined the Allies in April 1915 with the Treaty of London, which promised Italy the Austrian Littoral, northern Dalmatia, the port of Vlorë, most of the eastern Adriatic islands and Albania as a protectorate.[210] The treaty provided the basis for all the following divisions between Italy and Yugoslavia.[211] In 1918, the Montenegrin national assembly voted to unite with the Kingdom of Serbia, giving the latter access to the Adriatic.[212] Another short-lived, unrecognised state established in 1918 was the State of Slovenes, Croats and Serbs, formed from parts of Austria-Hungary, comprising most of the former monarchy's Adriatic coastline. Later that year, the Kingdom of Serbia and the State of Slovenes, Croats and Serbs formed the Kingdom of Serbs, Croats and Slovenes—subsequently renamed Yugoslavia. The proponents of the new union in the Croatian parliament saw the move as a safeguard against Italian expansionism as stipulated in the Treaty of London.[213] The treaty was largely disregarded by Britain and France because of conflicting promises made to Serbia and a perceived lack of Italian contribution to the war effort outside Italy itself.[214] The 1919 Treaty of Saint-Germain-en-Laye did transfer the Austrian Littoral and Istria to Italy, but awarded Dalmatia to Yugoslavia.[215] Following the war, a private force of demobilized Italian soldiers seized Rijeka and set up the Italian Regency of Carnaro—seen as a harbinger of Fascism—in order to force the recognition of Italian claims to the city.[216] After sixteen months of the Regency's existence, the 1920 Treaty of Rapallo redefined the Italian–Yugoslav borders, among other things transferring Zadar and the islands of Cres, Lastovo and Palagruža to Italy, securing the island of Krk for Yugoslavia and establishing the Free State of Fiume; this new state was abolished in 1924 by the Treaty of Rome that awarded Fiume (modern Rijeka) to Italy and Sušak to Yugoslavia.[217]
+
+During World War II, the Adriatic saw only limited naval action, starting with the Italian invasion of Albania and the joint Axis invasion of Yugoslavia. The latter led to the annexation of a large part of Dalmatia and nearly all the eastern Adriatic islands by Italy and the establishment of two puppet states, the Independent State of Croatia and the Kingdom of Montenegro, which controlled the remainder of the former Yugoslav Adriatic coast.[218] In 1947, after the Armistice between Italy and Allied armed forces and the war's end, Italy (now a republic) and the Allies signed the Treaty of Peace with Italy. The treaty reversed all wartime annexations, guaranteed the independence of Albania, created the Free Territory of Trieste (FTT) as a city-state, and gave communist Yugoslavia most of the Slovenian Littoral, as well as Istria, the islands of Cres, Lastovo and Palagruža, and the cities of Zadar and Rijeka.[219] The FTT was partitioned in 1954: Trieste itself and the area to the North of it were placed under Italian control, while the rest came under Yugoslav control. This arrangement was made permanent in the 1975 Treaty of Osimo.[220]
+
+During the Cold War, the Adriatic Sea became the southernmost flank of the Iron Curtain as Italy joined NATO,[221] while the Warsaw Pact established bases in Albania.[222] After the fall of communism, Yugoslavia broke apart: Slovenia and Croatia declared independence in 1991,[223] and Bosnia–Herzegovina followed in 1992,[224] while Montenegro remained in a federation with Serbia, officially called Serbia and Montenegro.[225] The ensuing Croatian War of Independence included limited naval engagements and a blockade of Croatia's coast by the Yugoslav Navy,[226] leading to the Battle of the Dalmatian channels and a later withdrawal of Yugoslav vessels.[227] Montenegro declared itself independent in 2006, effectively land-locking Serbia.[225] The period also saw the Adriatic Sea as the theatre of several NATO operations, including the blockade of Yugoslavia,[228] intervention in Bosnia-Herzegovina and the 1999 bombing of Yugoslavia.[229][230]
+
+Italy and Yugoslavia defined their Adriatic continental shelf delimitation in 1968,[231] with an additional agreement signed in 1975 on the Gulf of Trieste boundary, following the Treaty of Osimo. The boundary agreed in 1968 extends 353 nautical miles (654 km; 406 mi) and consists of 43 points connected by straight lines or circular arc segments. The additional boundary agreed upon in 1975 consists of 5 points, extending from an end point of the 1968 line. All successor states of former Yugoslavia accepted the agreements. In the Adriatic's southernmost areas the border was not determined in order to avoid prejudicing the location of the tripoint with the Albanian continental shelf border, which remains undefined. Before the breakup of Yugoslavia, Albania, Italy and Yugoslavia initially proclaimed 15-nautical-mile (28 km; 17 mi) territorial waters, subsequently reduced to international-standard 12 nautical miles (22 km; 14 mi) and all sides adopted baseline systems (mostly in the 1970s). Albania and Italy determined their sea border in 1992 according to the equidistance principle.[232] Following Croatian EU membership, the Adriatic became an internal sea of the EU.[233] The United Nations Convention on the Law of the Sea defines the Adriatic Sea as an enclosed or semi-enclosed sea.[234]
+
+The Adriatic Euroregion was established in Pula in 2006 to promote trans-regional and trans-national cooperation in the Adriatic Sea area and serve as an Adriatic framework to help resolve issues of regional importance. The Adriatic Euroregion consists of 23 members: the Apulia, Molise, Abruzzo, Marche, Emilia-Romagna, Veneto and Friuli-Venezia Giulia regions of Italy; the municipality of Izola in Slovenia; the Istria, Primorje-Gorski Kotar, Lika-Senj, Zadar, Šibenik-Knin, Split-Dalmatia and Dubrovnik-Neretva counties of Croatia; the Herzegovina-Neretva Canton of Bosnia–Herzegovina; the municipalities of Kotor and Tivat in Montenegro; the Fier, Vlorë, Tirana, Shkodër, Durrës and Lezhë counties of Albania; and the Greek prefectures of Thesprotia and Corfu.[235]
+
+The former Yugoslav republics' land borders were decided by demarcation commissions implementing the AVNOJ decisions of 1943 and 1945,[236][237] but the exact course has not been agreed upon by the successor states, which makes the maritime boundaries' definition difficult;[238] the maritime borders were not defined at all in the time of Yugoslavia.[239] In addition, the maritime boundary between Albania and Montenegro was not defined before the 1990s.[232]
+
+Croatia and Slovenia started negotiations to define maritime borders in the Gulf of Piran in 1992 but failed to agree, resulting in a dispute. Both countries also declared their economic zones, which partially overlap.[232][240] Croatia's application to become an EU member state was initially suspended pending resolution of its border disputes with Slovenia.[232] These disputes with Slovenia were eventually settled with an agreement to accept the decision of an international arbitration commission set up via the UN, enabling Croatia to progress towards EU membership.[241][242][243] Aside from the EU membership difficulty, even before its settling the dispute has caused no major practical problems.[232]
+
+The maritime boundary between Bosnia–Herzegovina and Croatia was formally settled in 1999, but a few issues are still in dispute—the Klek peninsula and two islets in the border area. The Croatia–Montenegro maritime boundary is disputed in the Bay of Kotor, at the Prevlaka peninsula. This dispute was exacerbated by the peninsula's occupation by the Yugoslav People's Army and later by the (Serbian–Montenegrin) FR Yugoslav Army, which in turn was replaced by a United Nations observer mission that lasted until 2002. Croatia took over the area with an agreement that allowed Montenegrin presence in the bay's Croatian waters, and the dispute has become far less contentious since Montenegro's independence in 2006.[232]
+
+The Adriatic Sea fishery's production is distributed among countries in the basin.[244] In 2000, the nominal—on a live weight basis—total landings of all Adriatic fisheries reached 110,000 tonnes (108,000 long tons).[245] Overfishing is a recognised problem—450 species of fish live in the Adriatic Sea, including 120 species threatened by excessive commercial fishing, a problem exacerbated by pollution and global warming. Overexploited species include common dentex, red scorpionfish, monkfish, John Dory, blue shark, spiny dogfish,[246] mullet, red mullet, Norway lobster,[247] as well as European hake,[248] and sardines.[249] Turtles and common bottlenose dolphins are also being killed by fishing nets. The depleted fish stock, and Croatia's Ecological and Fisheries Protection Zone (ZERP) contributed to accusations of overfishing exchanged between Italian and Croatian fishermen.[246] ZERP was introduced in 2003, but its application to EU member states was suspended in 2004.[233] The depleted stocks of fish are being addressed through a new proposed EU fisheries policy that was scheduled to take effect in 2013, when Croatia acceded to the EU,[250] and restore the stocks to sustainable levels by 2015.[251]
+
+The largest volume of fish harvesting was in Italy, where the total production volume in 2007 stood at 465,637 tonnes (458,283 long tons).[244] In 2003, 28.8% of Italian fisheries production volume was generated in the Northern and central Adriatic, and 24.5% in Apulia (from the Southern Adriatic and Ionian Sea). Italian fisheries, including those operating outside the Adriatic, employed 60,700 in the primary sector, including aquaculture (which comprises 40% of the total fisheries production). The total fisheries output's gross value in 2002 was $1.9 billion.[252]
+
+In 2007, Croatia's production in live weight reached 53,083 tonnes (52,245 long tons).[244] In 2006, the total Croatian fisheries production volume was 37,800 tonnes (37,200 long tons) of catch and 14,200 tonnes (14,000 long tons) from marine aquaculture. Croatian fisheries employed approximately 20,000. The 2006 marine capture catch in Croatian waters consisted of sardines (44.8%), anchovies (31.3%), tunas (2.7%), other pelagic fish (4.8%), hake (2.4%), mullet (2.1%), other demersal fish (8.3%), crustaceans (largely lobster and Nephrops norvegicus) (0.8%), shellfish (largely oysters and mussels) (0.3%), cuttlefish (0.6%), squids (0.2%) and octopuses and other cephalopods (1.6%). Croatian marine aquaculture production consisted of tuna (47.2%), oysters and mussels (28.2% combined) and bass and bream (24.6% combined).[253]
+
+In 2007, Albanian fisheries production amounted to 7,505 tonnes (7,386 long tons),[244] including aquaculture production, which reached 1,970 tonnes (1,940 long tons) in 2006. At the same time, Slovenian fisheries produced a total of 2,500 tonnes (2,460 long tons) with 55% of the production volume originating in aquaculture, representing the highest ratio in the Adriatic. Finally, the Montenegrin fisheries production stood at 911 tonnes (897 long tons) in 2006, with only 11 tonnes coming from aquaculture.[254] In 2007, the fisheries production in Bosnia–Herzegovina reached volume of 9,625 tonnes (9,473 long tons) and 2,463 tonnes (2,424 long tons) in Slovenia.[244]
+
+The countries bordering the Adriatic Sea are significant tourist destinations. The largest number of tourist overnight stays and the most numerous tourist accommodation facilities are recorded in Italy, especially in the Veneto region (around Venice). Veneto is followed by the Emilia-Romagna region and by the Adriatic Croatian counties. The Croatian tourist facilities are further augmented by 21,000 nautical ports and moorings; nautical tourists are attracted to various types of marine protected areas.[107]
+
+All countries along the Adriatic coast, except Albania and Bosnia–Herzegovina, take part in the Blue Flag beach certification programme (of the Foundation for Environmental Education), for beaches and marinas meeting strict quality standards including environmental protection, water quality, safety and services criteria.[255] As of January 2012, the Blue Flag has been awarded to 103 Italian Adriatic beaches and 29 marinas, 116 Croatian beaches and 19 marinas, 7 Slovenian beaches and 2 marinas, and 16 Montenegrin beaches.[256] Adriatic tourism is a significant source of income for these countries, especially in Croatia and Montenegro where the tourism income generated along the Adriatic coast represents the bulk of such income.[257][258] The direct contribution of travel and tourism to Croatia's GDP stood at 5.1% in 2011, with the total industry contribution estimated at 12.8% of the national GDP.[259] For Montenegro, the direct contribution of tourism to the national GDP is 8.1%, with the total contribution to the economy at 17.2% of Montenegrin GDP.[260] Tourism in Adriatic Croatia has recently exhibited greater growth than in the other regions around the Adriatic.[261]
+
+There are nineteen Adriatic Sea ports (in four different countries) that each handle more than a million tonnes of cargo per year. The largest cargo ports among them are the Port of Trieste (the largest Adriatic cargo port in Italy), the Port of Venice, the Port of Ravenna, the Port of Koper (the largest Slovenian port),[268] the Port of Rijeka (the largest Croatian cargo port), and the Port of Brindisi. The largest passenger ports in the Adriatic are the Port of Split (the largest Croatian passenger port) and ports in Ancona (the largest Italian passenger seaport in the Adriatic).[269][270][271][272] The largest seaport in Montenegro is the Port of Bar.[273] In 2010, the Northern Adriatic seaports of Trieste, Venice, Ravenna, Koper and Rijeka founded the North Adriatic Ports Association to position themselves more favourably in the EU's transport systems.[274][275]
+
+Natural gas is produced through several projects, including a joint venture of the Eni and INA companies that operates two platforms—one is in Croatian waters and draws gas from six wells, and the other (which started operating in 2010) is located in Italian waters. The Adriatic gas fields were discovered in the 1970s,[280]:265   but their development commenced in 1996. In 2008, INA produced 14.58 million BOE per day of gas.[281] About 100 offshore platforms are located in the Emilia-Romagna region,[107] along with 17 in the Northern Adriatic.[282] Eni estimated its concessions in the Adriatic Sea to hold at least 40,000,000,000 cubic metres (1.4×1012 cu ft) of natural gas, adding that they may even reach 100,000,000,000 cubic metres (3.5×1012 cu ft). INA estimates, however, are 50% lower than those supplied by Eni.[283] Oil was discovered in the Northern Adriatic at a depth of approximately 5,400 metres (17,700 ft); the discovery was assessed as not viable because of its location, depth and quality.[284] These gas and oil reserves are part of the Po basin Province of Northern Italy and the Northern Mediterranean Sea.[285]
+
+In the 2000s, investigation works aimed at discovering gas and oil reserves in the Middle and Southern Adriatic basins intensified, and by the decade's end, oil and natural gas reserves were discovered southeast of the Bari, Brindisi—Rovesti and Giove oil discoveries. Surveys indicate reserves of 3 billion barrels of oil in place and 5.7×1010 cubic metres (2,000,000,000,000 cu ft) of gas in place.[286] The discovery was followed by further surveys off the Croatian coast.[287] In January 2012, INA commenced prospecting for oil off Dubrovnik, marking the resumption of oil exploration along the eastern Adriatic coast after surveys commenced in the late 1980s around the island of Brač were cancelled because of Yugoslavia's breakup and war in Croatia. Montenegro is also expected to look for oil off its coast.[288] As of January 2012, only 200 exploration wells had been sunk off the Croatian coast, with all but 30 in the Northern Adriatic basin.[289]
+

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+
+
+The Baltic Sea is a mediterranean sea of the Atlantic Ocean, enclosed by Denmark, Estonia, Finland, Latvia, Lithuania, Sweden, northeast Germany, Poland, Russia and the North and Central European Plain.
+
+The sea stretches from 53°N to 66°N latitude and from 10°E to 30°E longitude. A marginal sea of the Atlantic, with limited water exchange between the two water bodies, the Baltic Sea drains through the Danish Straits into the Kattegat by way of the Øresund, Great Belt and Little Belt.  It includes the Gulf of Bothnia, the Bay of Bothnia, the Gulf of Finland, the Gulf of Riga and the Bay of Gdańsk.
+
+The Baltic Proper is bordered on its northern edge, at the latitude 60°N, by the Åland islands and the Gulf of Bothnia, on its northeastern edge by the Gulf of Finland, on its eastern edge by the Gulf of Riga, and in the west by the Swedish part of the southern Scandinavian Peninsula.
+
+The Baltic Sea is connected by artificial waterways to the White Sea via the White Sea–Baltic Canal and to the German Bight of the North Sea via the Kiel Canal.
+
+Administration
+
+The Helsinki Convention on the Protection of the Marine Environment of the Baltic Sea Area includes the Baltic Sea and the Kattegat, without calling Kattegat a part of the Baltic Sea, "For the purposes of this Convention the 'Baltic Sea Area' shall be the Baltic Sea and the Entrance to the Baltic Sea, bounded by the parallel of the Skaw in the Skagerrak at 57°44.43'N."[3]
+
+Traffic history
+
+Historically, the Kingdom of Denmark collected Sound Dues from ships at the border between the ocean and the land-locked Baltic Sea, in tandem: in the Øresund at Kronborg castle near Helsingør; in the Great Belt at Nyborg; and in the Little Belt at its narrowest part then Fredericia, after that stronghold was built. The narrowest part of Little Belt is the "Middelfart Sund" near Middelfart.[4]
+
+Oceanography
+
+Geographers widely agree that the preferred physical border of the Baltic is a line drawn through the southern Danish islands, Drogden-Sill and Langeland.[5] The Drogden Sill is situated north of Køge Bugt and connects Dragør in the south of Copenhagen to Malmö; it is used by the Øresund Bridge, including the Drogden Tunnel. By this definition, the Danish Straits are part of the entrance, but the Bay of Mecklenburg and the Bay of Kiel are parts of the Baltic Sea.
+Another usual border is the line between Falsterbo, Sweden and Stevns Klint, Denmark, as this is the southern border of Øresund. It's also the border between the shallow southern Øresund (with a typical depth of 5–10 meters only) and notably deeper water.
+
+Hydrography and biology
+
+Drogden Sill (depth of 7 m (23 ft)) sets a limit to Øresund and Darss Sill (depth of 18 m (59 ft)), and a limit to the Belt Sea.[6] The shallow sills are obstacles to the flow of heavy salt water from the Kattegat into the basins around Bornholm and Gotland.
+
+The Kattegat and the southwestern Baltic Sea are well oxygenated and have a rich biology. The remainder of the Sea is brackish, poor in oxygen and in species. Thus, statistically, the more of the entrance that is included in its definition, the healthier the Baltic appears; conversely, the more narrowly it is defined, the more endangered its biology appears.
+
+Tacitus called it Mare Suebicum after the Germanic people of the Suebi,[7] and Ptolemy Sarmatian Ocean after the Sarmatians,[8] but the first to name it the Baltic Sea (Mare Balticum) was the eleventh-century German chronicler Adam of Bremen. The origin of the latter name is speculative and it was adopted into Slavic and Finnic languages spoken around the sea, very likely due to the role of Medieval Latin in cartography. It might be connected to the Germanic word belt, a name used for two of the Danish straits, the Belts, while others claim it to be directly derived from the source of the Germanic word, Latin balteus "belt".[9] Adam of Bremen himself compared the sea with a belt, stating that it is so named because it stretches through the land as a belt (Balticus, eo quod in modum baltei longo tractu per Scithicas regiones tendatur usque in Greciam).
+
+He might also have been influenced by the name of a legendary island mentioned in the Natural History of Pliny the Elder. Pliny mentions an island named Baltia (or Balcia) with reference to accounts of Pytheas and Xenophon. It is possible that Pliny refers to an island named Basilia ("the royal") in On the Ocean by Pytheas. Baltia also might be derived from belt and mean "near belt of sea, strait".
+
+Meanwhile, others have suggested that the name of the island originates from the Proto-Indo-European root *bhel meaning "white, fair".[10] This root and its basic meaning were retained in Lithuanian (as baltas), Latvian (as balts) and Slavic (as bely). On this basis, a related hypothesis holds that the name originated from this Indo-European root via a Baltic language such as Lithuanian.[11] Another explanation is that, while derived from the aforementioned root, the name of the sea is related to names for various forms of water and related substances in several European languages, that might have been originally associated with colors found in swamps (compare Proto-Slavic *bolto "swamp"). Yet another explanation is that the name originally meant "enclosed sea, bay" as opposed to open sea.[12] Some Swedish historians believe the name derives from the god Baldr of Nordic mythology.
+
+In the Middle Ages the sea was known by a variety of names. The name Baltic Sea became dominant only after 1600. Usage of Baltic and similar terms to denote the region east of the sea started only in 19th century.
+
+The Baltic Sea was known in ancient Latin language sources as Mare Suebicum or even Mare Germanicum.[13] Older native names in languages that used to be spoken on the shores of the sea or near it usually indicate the geographical location of the sea (in Germanic languages), or its size in relation to smaller gulfs (in Old Latvian), or tribes associated with it (in Old Russian the sea was known as the Varanghian Sea). In modern languages it is known by the equivalents of "East Sea", "West Sea", or "Baltic Sea" in different languages:
+
+At the time of the Roman Empire, the Baltic Sea was known as the Mare Suebicum or Mare Sarmaticum. Tacitus in his AD 98 Agricola and Germania described the Mare Suebicum, named for the Suebi tribe, during the spring months, as a brackish sea where the ice broke apart and chunks floated about. The Suebi eventually migrated southwest to temporarily reside in the Rhineland area of modern Germany, where their name survives in the historic region known as Swabia. Jordanes called it the Germanic Sea in his work, the Getica.
+
+In the early Middle Ages, Norse (Scandinavian) merchants built a trade empire all around the Baltic. Later, the Norse fought for control of the Baltic against Wendish tribes dwelling on the southern shore. The Norse also used the rivers of Russia for trade routes, finding their way eventually to the Black Sea and southern Russia. This Norse-dominated period is referred to as the Viking Age.
+
+Since the Viking Age, the Scandinavians have referred to the Baltic Sea as Austmarr ("Eastern Lake"). "Eastern Sea", appears in the Heimskringla and Eystra salt appears in Sörla þáttr. Saxo Grammaticus recorded in Gesta Danorum an older name, Gandvik, -vik being Old Norse for "bay", which implies that the Vikings correctly regarded it as an inlet of the sea. Another form of the name, "Grandvik", attested in at least one English translation of Gesta Danorum, is likely to be a misspelling.)
+
+In addition to fish the sea also provides amber, especially from its southern shores within today's borders of Poland, Russia and Lithuania. First mentions of amber deposits on the South coast of the Baltic Sea date back to the 12th century.[14] The bordering countries have also traditionally exported lumber, wood tar, flax, hemp and furs by ship across the Baltic. Sweden had from early medieval times exported iron and silver mined there, while Poland had and still has extensive salt mines. Thus the Baltic Sea has long been crossed by much merchant shipping.
+
+The lands on the Baltic's eastern shore were among the last in Europe to be converted to Christianity. This finally happened during the Northern Crusades: Finland in the twelfth century by Swedes, and what are now Estonia and Latvia in the early thirteenth century by Danes and Germans (Livonian Brothers of the Sword). The Teutonic Order gained control over parts of the southern and eastern shore of the Baltic Sea, where they set up their monastic state. Lithuania was the last European state to convert to Christianity.
+
+In the period between the 8th and 14th centuries, there was much piracy in the Baltic from the coasts of Pomerania and Prussia, and the Victual Brothers held Gotland.
+
+Starting in the 11th century, the southern and eastern shores of the Baltic were settled by migrants mainly from Germany, a movement called the Ostsiedlung ("east settling"). Other settlers were from the Netherlands, Denmark, and Scotland. The Polabian Slavs were gradually assimilated by the Germans.[15] Denmark gradually gained control over most of the Baltic coast, until she lost much of her possessions after being defeated in the 1227 Battle of Bornhöved.
+
+In the 13th to 16th centuries, the strongest economic force in Northern Europe was the Hanseatic League, a federation of merchant cities around the Baltic Sea and the North Sea. In the sixteenth and early seventeenth centuries, Poland, Denmark, and Sweden fought wars for Dominium maris baltici ("Lordship over the Baltic Sea"). Eventually, it was Sweden that virtually encompassed the Baltic Sea. In Sweden the sea was then referred to as Mare Nostrum Balticum ("Our Baltic Sea"). The goal of Swedish warfare during the 17th century was to make the Baltic Sea an all-Swedish sea (Ett Svenskt innanhav), something that was accomplished except the part between Riga in Latvia and Stettin in Pomerania.  However, the Dutch dominated Baltic trade in the seventeenth century.
+
+In the eighteenth century, Russia and Prussia became the leading powers over the sea. Sweden's defeat in the Great Northern War brought Russia to the eastern coast. Russia became and remained a dominating power in the Baltic. Russia's Peter the Great saw the strategic importance of the Baltic and decided to found his new capital, Saint Petersburg, at the mouth of the Neva river at the east end of the Gulf of Finland. There was much trading not just within the Baltic region but also with the North Sea region, especially eastern England and the Netherlands: their fleets needed the Baltic timber, tar, flax and hemp.
+
+During the Crimean War, a joint British and French fleet attacked the Russian fortresses in the Baltic. They bombarded Sveaborg, which guards Helsinki; and Kronstadt, which guards Saint Petersburg; and they destroyed Bomarsund in the Åland Islands. After the unification of Germany in 1871, the whole southern coast became German. World War I was partly fought in the Baltic Sea. After 1920 Poland was connected to the Baltic Sea by the Polish Corridor and enlarged the port of Gdynia in rivalry with the port of the Free City of Danzig.
+
+During World War II, Germany reclaimed all of the southern and much of the eastern shore by occupying Poland and the Baltic states. In 1945, the Baltic Sea became a mass grave for retreating soldiers and refugees on torpedoed troop transports. The sinking of the Wilhelm Gustloff remains the worst maritime disaster in history, killing (very roughly) 9,000 people. In 2005, a Russian group of scientists found over five thousand airplane wrecks, sunken warships, and other material, mainly from World War II, on the bottom of the sea.
+
+Since the end of World War II, various nations, including the Soviet Union, the United Kingdom and the United States have disposed of chemical weapons in the Baltic Sea, raising concerns of environmental contamination.[16] Today, fishermen occasionally find some of these materials: the most recent available report from the Helsinki Commission notes that four small scale catches of chemical munitions representing approximately 105 kg (231 lb) of material were reported in 2005. This is a reduction from the 25 incidents representing 1,110 kg (2,450 lb) of material in 2003.[17] Until now, the U.S. Government refuses to disclose the exact coordinates of the wreck sites. Deteriorating bottles leak mustard gas and other substances, thus slowly poisoning a substantial part of the Baltic Sea.
+
+After 1945, the German population was expelled from all areas east of the Oder-Neisse line, making room for displaced Poles and Russians. Poland gained most of the southern shore. The Soviet Union gained another access to the Baltic with the Kaliningrad Oblast. The Baltic states on the eastern shore were annexed by the Soviet Union. The Baltic then separated opposing military blocs: NATO and the Warsaw Pact. Had war broken out, the Polish navy was prepared to invade the Danish isles. Neutral Sweden developed incident weapons to defend its territorial waters after the Swedish submarine incidents.[18] This border status restricted trade and travel. It ended only after the collapse of the Communist regimes in Central and Eastern Europe in the late 1980s.
+
+Since May 2004, with the accession of the Baltic states and Poland, the Baltic Sea has been almost entirely surrounded by countries of the European Union (EU). The remaining non-EU shore areas are Russian: the Saint Petersburg area and the Kaliningrad Oblast exclave.
+
+Winter storms begin arriving in the region during October. These have caused numerous shipwrecks, and contributed to the extreme difficulties of rescuing passengers of the ferry M/S Estonia en route from Tallinn, Estonia, to Stockholm, Sweden, in September 1994, which claimed the lives of 852 people. Older, wood-based shipwrecks such as the Vasa tend to remain well-preserved, as the Baltic's cold and brackish water does not suit the shipworm.
+
+Storm surge floodings are generally taken to occur when the water level is more than one metre above normal. In Warnemünde about 110 floods occurred from 1950 to 2000, an average of just over two per year.[19]
+
+Historic flood events were the All Saints' Flood of 1304 and other floods in the years 1320, 1449, 1625, 1694, 1784 and 1825. Little is known of their extent.[20] From 1872, there exist regular and reliable records of water levels in the Baltic Sea. The highest was the flood of 1872 when the water was an average of 2.43 m (8 ft 0 in) above sea level at Warnemünde and a maximum of 2.83 m (9 ft 3 in) above sea level in Warnemünde. In the last very heavy floods the average water levels reached 1.88 m (6 ft 2 in) above sea level in 1904, 1.89 m (6 ft 2 in) in 1913, 1.73 m (5 ft 8 in) in January 1954, 1.68 m (5 ft 6 in) on 2–4 November 1995 and 1.65 m (5 ft 5 in) on 21 February 2002.[21]
+
+An arm of the North Atlantic Ocean, the Baltic Sea is enclosed by Sweden and Denmark to the west, Finland to the northeast, the Baltic countries to the southeast, and the North European Plain to the southwest.
+
+It is about 1,600 km (990 mi) long, an average of 193 km (120 mi) wide, and an average of 55 metres (180 ft) deep. The maximum depth is 459 m (1,506 ft) which is on the Swedish side of the center. The surface area is about 349,644 km2 (134,998 sq mi) [22] and the volume is about 20,000 km3 (4,800 cu mi). The periphery amounts to about 8,000 km (5,000 mi) of coastline.[23]
+
+The Baltic Sea is one of the largest brackish inland seas by area, and occupies a basin (a zungenbecken) formed by glacial erosion during the last few ice ages.
+
+Physical characteristics of the Baltic Sea, its main sub-regions, and the transition zone to the Skagerrak/North Sea area[24]
+
+The International Hydrographic Organization defines the limits of the Baltic Sea as follows:[25]
+
+The northern part of the Baltic Sea is known as the Gulf of Bothnia, of which the northernmost part is the Bay of Bothnia  or Bothnian Bay. The more rounded southern basin of the gulf is called Bothnian Sea and immediately to the south of it lies the Sea of Åland. The Gulf of Finland connects the Baltic Sea with Saint Petersburg. The Gulf of Riga lies between the Latvian capital city of Riga and the Estonian island of Saaremaa.
+
+The Northern Baltic Sea lies between the Stockholm area, southwestern Finland and Estonia. The Western and Eastern Gotland basins form the major parts of the Central Baltic Sea or Baltic proper. The Bornholm Basin is the area east of Bornholm, and the shallower Arkona Basin extends from Bornholm to the Danish isles of Falster and Zealand.
+
+In the south, the Bay of Gdańsk lies east of the Hel Peninsula on the Polish coast and west of the Sambia Peninsula in Kaliningrad Oblast. The Bay of Pomerania lies north of the islands of Usedom and Wolin, east of Rügen. Between Falster and the German coast lie the Bay of Mecklenburg and Bay of Lübeck. The westernmost part of the Baltic Sea is the Bay of Kiel. The three Danish straits, the Great Belt, the Little Belt and The Sound (Öresund/Øresund), connect the Baltic Sea with the Kattegat and Skagerrak strait in the North Sea.
+
+The water temperature of the Baltic Sea varies significantly depending on exact location, season and depth. At the Bornholm Basin, which is located directly east of the island of the same name, the surface temperature typically falls to 0–5 °C (32–41 °F) during the peak of the winter and rises to 15–20 °C (59–68 °F) during the peak of the summer, with an annual average of around 9–10 °C (48–50 °F).[27] A similar pattern can be seen in the Gotland Basin, which is located between the island of Gotland and Latvia. In the deep of these basins the temperature variations are smaller. At the bottom of the Bornholm Basin, deeper than 80 m (260 ft), the temperature typically is 1–10 °C (34–50 °F), and at the bottom of the Gotland Basin, at depths greater than 225 m (738 ft), the temperature typically is 4–7 °C (39–45 °F).[27]
+
+On the long-term average, the Baltic Sea is ice-covered at the annual maximum for about 45% of its surface area. The ice-covered area during such a typical winter includes the Gulf of Bothnia, the Gulf of Finland, the Gulf of Riga, the archipelago west of Estonia, the Stockholm archipelago, and the Archipelago Sea southwest of Finland. The remainder of the Baltic does not freeze during a normal winter, except sheltered bays and shallow lagoons such as the Curonian Lagoon. The ice reaches its maximum extent in February or March; typical ice thickness in the northernmost areas in the Bothnian Bay, the northern basin of the Gulf of Bothnia, is about 70 cm (28 in) for landfast sea ice. The thickness decreases farther south.
+
+Freezing begins in the northern extremities of the Gulf of Bothnia typically in the middle of November, reaching the open waters of the Bothnian Bay in early January. The Bothnian Sea, the basin south of Kvarken, freezes on average in late February. The Gulf of Finland and the Gulf of Riga freeze typically in late January. In 2011, the Gulf of Finland was completely frozen on 15 February.[28]
+
+The ice extent depends on whether the winter is mild, moderate, or severe. In severe winters ice can form around southern Sweden and even in the Danish straits. According to the 18th-century natural historian William Derham, during the severe winters of 1703 and 1708, the ice cover reached as far as the Danish straits.[29] Frequently, parts of the Gulf of Bothnia and Gulf of Finland are frozen, in addition to coastal fringes in more southerly locations such as the Gulf of Riga. This description meant that the whole of the Baltic Sea was covered with ice.
+
+Since 1720, the Baltic Sea has frozen over entirely 20 times, most recently in early 1987, which was the most severe winter in Scandinavia since 1720. The ice then covered 400,000 km2 (150,000 sq mi). During the winter of 2010–11, which was quite severe compared to those of the last decades, the maximum ice cover was 315,000 km2 (122,000 sq mi), which was reached on 25 February 2011. The ice then extended from the north down to the northern tip of Gotland, with small ice-free areas on either side, and the east coast of the Baltic Sea was covered by an ice sheet about 25 to 100 km (16 to 62 mi) wide all the way to Gdańsk. This was brought about by a stagnant high-pressure area that lingered over central and northern Scandinavia from around 10 to 24 February. After this, strong southern winds pushed the ice further into the north, and much of the waters north of Gotland were again free of ice, which had then packed against the shores of southern Finland.[30] The effects of the afore-mentioned high-pressure area did not reach the southern parts of the Baltic Sea, and thus the entire sea did not freeze over. However, floating ice was additionally observed near Świnoujście harbour in January 2010.
+
+In recent years before 2011, the Bothnian Bay and the Bothnian Sea were frozen with solid ice near the Baltic coast and dense floating ice far from it. In 2008, almost no ice formed except for a short period in March.[31]
+
+During winter, fast ice, which is attached to the shoreline, develops first, rendering ports unusable without the services of icebreakers. Level ice, ice sludge, pancake ice, and rafter ice form in the more open regions. The gleaming expanse of ice is similar to the Arctic, with wind-driven pack ice and ridges up to 15 m (49 ft). Offshore of the landfast ice, the ice remains very dynamic all year, and it is relatively easily moved around by winds and therefore forms pack ice, made up of large piles and ridges pushed against the landfast ice and shores.
+
+In spring, the Gulf of Finland and the Gulf of Bothnia normally thaw in late April, with some ice ridges persisting until May in the eastern extremities of the Gulf of Finland. In the northernmost reaches of the Bothnian Bay, ice usually stays until late May; by early June it is practically always gone. However, in the famine year of 1867 remnants of ice were observed as late as 17 July near Uddskär.[32] Even as far south as Øresund, remnants of ice have been observed in May on several occasions; near Taarbaek on 15 May 1942 and near Copenhagen on 11 May 1771. Drift ice was also observed on 11 May 1799.[33][34][35]
+
+The ice cover is the main habitat for two large mammals, the grey seal (Halichoerus grypus) and the Baltic ringed seal (Pusa hispida botnica), both of which feed underneath the ice and breed on its surface. Of these two seals, only the Baltic ringed seal suffers when there is not adequate ice in the Baltic Sea, as it feeds its young only while on ice. The grey seal is adapted to reproducing also with no ice in the sea. The sea ice also harbours several species of algae that live in the bottom and inside unfrozen brine pockets in the ice.
+
+The Baltic Sea flows out through the Danish straits; however, the flow is complex. A surface layer of brackish water discharges 940 km3 (230 cu mi) per year into the North Sea. Due to the difference in salinity, by salinity permeation principle, a sub-surface layer of more saline water moving in the opposite direction brings in 475 km3 (114 cu mi) per year. It mixes very slowly with the upper waters, resulting in a salinity gradient from top to bottom, with most of the salt water remaining below 40 to 70 m (130 to 230 ft) deep. The general circulation is anti-clockwise: northwards along its eastern boundary, and south along the western one .[36]
+
+The difference between the outflow and the inflow comes entirely from fresh water. More than 250 streams drain a basin of about 1,600,000 km2 (620,000 sq mi), contributing a volume of 660 km3 (160 cu mi) per year to the Baltic. They include the major rivers of north Europe, such as the Oder, the Vistula, the Neman, the Daugava and the Neva. Additional fresh water comes from the difference of precipitation less evaporation, which is positive.
+
+An important source of salty water are infrequent inflows of North Sea water into the Baltic. Such inflows, are important to the Baltic ecosystem because of the oxygen they transport into the Baltic deeps, used to happen regularly until the 1980s. In recent decades they have become less frequent. The latest four occurred in 1983, 1993, 2003 and 2014 suggesting a new inter-inflow period of about ten years.
+
+The water level is generally far more dependent on the regional wind situation than on tidal effects. However, tidal currents occur in narrow passages in the western parts of the Baltic Sea.
+
+The significant wave height is generally much lower than that of the North Sea. Quite violent, sudden storms sweep the surface ten or more times a year, due to large transient temperature differences and a long reach of wind. Seasonal winds also cause small changes in sea level, of the order of 0.5 m (1 ft 8 in) .[36]
+
+The Baltic Sea is the world's largest inland brackish sea.[37] Only two other brackish waters are larger on some measurements: The Black Sea is larger in both surface area and water volume, but most of it is located outside the continental shelf (only a small percentage is inland). The Caspian Sea is larger in water volume, but—despite its name��it is a lake rather than a sea.[37]
+
+The Baltic Sea's salinity is much lower than that of ocean water (which averages 3.5%), as a result of abundant freshwater runoff from the surrounding land (rivers, streams and alike), combined with the shallowness of the sea itself; runoff contributes roughly one-fortieth its total volume per year, as the volume of the basin is about 21,000 km3 (5,000 cu mi) and yearly runoff is about 500 km3 (120 cu mi).[citation needed]
+
+The open surface waters of the Baltic Sea "proper" generally have a salinity of 0.3 to 0.9%, which is border-line freshwater. The flow of fresh water into the sea from approximately two hundred rivers and the introduction of salt from the southwest builds up a gradient of salinity in the Baltic Sea. The highest surface salinities, generally 0.7–0.9%, is in the southwestern-most part of the Baltic, in the Arkona and Bornholm basins (the former located roughly between southeast Zealand and Bornholm, and the latter directly east of Bornholm). It gradually falls further east and north, reaching the lowest in the Bothnian Bay at around 0.3%.[38] Drinking the surface water of the Baltic as a means of survival would actually hydrate the body instead of dehydrating, as is the case with ocean water.[note 1][citation needed]
+
+As salt water is denser than fresh water, the bottom of the Baltic Sea is saltier than the surface. This creates a vertical stratification of the water column, a halocline, that represents a barrier to the exchange of oxygen and nutrients, and fosters completely separate maritime environments.[39] The difference between the bottom and surface salinities vary depending on location. Overall it follows the same southwest to east and north pattern as the surface. At the bottom of the Arkona Basin (equalling depths greater than 40 m or 130 ft) and Bornholm Basin (depths greater than 80 m or 260 ft) it is typically 1.4–1.8%. Further east and north the salinity at the bottom is consistently lower, being the lowest in Bothnian Bay (depths greater than 120 m or 390 ft) where it is slightly below 0.4%, or only marginally higher than the surface in the same region.[38]
+
+In contrast, the salinity of the Danish straits, which connect the Baltic Sea and Kattegat, tends to be significantly higher, but with major variations from year to year. For example, the surface and bottom salinity in the Great Belt is typically around 2.0% and 2.8% respectively, which is only somewhat below that of the Kattegat.[38] The water surplus caused by the continuous inflow of rivers and streams to the Baltic Sea means that there generally is a flow of brackish water out though the Danish straits to the Kattegat (and eventually the Atlantic).[40] Significant flows in the opposite direction, salt water from the Kattegat through the Danish straits to the Baltic Sea, are less regular. From 1880 to 1980 inflows occurred on average six to seven times per decade. Since 1980 it has been much less frequent, although a very large inflow occurred in 2014.[27]
+
+The rating of mean discharges differs from the ranking of hydrological lengths (from the most distant source to the sea) and the rating of the nominal lengths. Göta älv, a tributary of the Kattegat, is not listed, as due to the northward upper low-salinity-flow in the sea, its water hardly reaches the Baltic proper:
+
+Countries that border the sea:
+
+Denmark,  Estonia,  Finland,  Germany,  Latvia,  Lithuania,  Poland,  Russia,  Sweden.
+
+Countries lands in the outer drainage basin:
+
+Belarus,  Czech Republic,  Norway,  Slovakia,  Ukraine.
+
+The Baltic sea drainage basin is roughly four times the surface area of the sea itself. About 48% of the region is forested, with Sweden and Finland containing the majority of the forest, especially around the Gulfs of Bothnia and Finland.
+
+About 20% of the land is used for agriculture and pasture, mainly in Poland and around the edge of the Baltic Proper, in Germany, Denmark and Sweden. About 17% of the basin is unused open land with another 8% of wetlands. Most of the latter are in the Gulfs of Bothnia and Finland.
+
+The rest of the land is heavily populated. About 85 million people live in the Baltic drainage basin, 15 million within 10 km (6 mi) of the coast and 29 million within 50 km (31 mi) of the coast. Around 22 million live in population centers of over 250,000. 90% of these are concentrated in the 10 km (6 mi) band around the coast. Of the nations containing all or part of the basin, Poland includes 45% of the 85 million, Russia 12%, Sweden 10% and the others less than 6% each.[41]
+
+The biggest coastal cities (by population):
+
+Other important ports:
+
+The Baltic Sea somewhat resembles a riverbed, with two tributaries, the Gulf of Finland and Gulf of Bothnia. Geological surveys show that before the Pleistocene, instead of the Baltic Sea, there was a wide plain around a great river that paleontologists call the Eridanos. Several Pleistocene glacial episodes scooped out the river bed into the sea basin. By the time of the last, or Eemian Stage (MIS 5e), the Eemian Sea was in place. Instead of a true sea, the Baltic can even today also be understood as the common estuary of all rivers flowing into it.
+
+From that time the waters underwent a geologic history summarized under the names listed below. Many of the stages are named after marine animals (e.g. the Littorina mollusk) that are clear markers of changing water temperatures and salinity.
+
+The factors that determined the sea's characteristics were the submergence or emergence of the region due to the weight of ice and subsequent isostatic readjustment, and the connecting channels it found to the North Sea-Atlantic, either through the straits of Denmark or at what are now the large lakes of Sweden, and the White Sea-Arctic Sea.
+
+The land is still emerging isostatically from its depressed state, which was caused by the weight of ice during the last glaciation. The phenomenon is known as post-glacial rebound. Consequently, the surface area and the depth of the sea are diminishing. The uplift is about eight millimetres per year on the Finnish coast of the northernmost Gulf of Bothnia. In the area, the former seabed is only gently sloping, leading to large areas of land being reclaimed in what are, geologically speaking, relatively short periods (decades and centuries).
+
+The "Baltic Sea anomaly" refers to interpretations of an indistinct sonar image taken by Swedish salvage divers on the floor of the northern Baltic Sea in June 2011. The treasure hunters suggested the image showed an object with unusual features of seemingly extraordinary origin. Speculation published in tabloid newspapers claimed that the object was a sunken UFO. A consensus of experts and scientists say that the image most likely shows a natural geological formation.[43][44][45][46][47]
+
+The fauna of the Baltic Sea is a mixture of marine and freshwater species. Among marine fishes are Atlantic cod, Atlantic herring, European hake, European plaice, European flounder, shorthorn sculpin and turbot, and examples of freshwater species include European perch, northern pike, whitefish and common roach. Freshwater species may occur at outflows of rivers or streams in all coastal sections of the Baltic Sea. Otherwise marine species dominate in most sections of the Baltic, at least as far north as Gävle, where less than one-tenth are freshwater species. Further north the pattern is inverted. In the Bothnian Bay, roughly two-thirds of the species are freshwater. In the far north of this bay, saltwater species are almost entirely absent.[27] For example, the common starfish and shore crab, two species that are very widespread along European coasts, are both unable to cope with the significantly lower salinity. Their range limit is west of Bornholm, meaning that they are absent from the vast majority of the Baltic Sea.[27] Some marine species, like the Atlantic cod and European flounder, can survive at relatively low salinities, but need higher salinities to breed, which therefore occurs in deeper parts of the Baltic Sea.[48][49]
+
+There is a decrease in species richness from the Danish belts to the Gulf of Bothnia. The decreasing salinity along this path causes restrictions in both physiology and habitats.[50] At more than 600 species of invertebrates, fish, aquatic mammals, aquatic birds and macrophytes, the Arkona Basin (roughly between southeast Zealand and Bornholm) is far richer than other more eastern and northern basins in the Baltic Sea, which all have less than 400 species from these groups, with the exception of the Gulf of Finland with more than 750 species. However, even the most diverse sections of the Baltic Sea have far less species than the almost-full saltwater Kattegat, which is home to more than 1600 species from these groups.[27] The lack of tides has affected the marine species as compared with the Atlantic.
+
+Since the Baltic Sea is so young there are only two or three known endemic species: the brown alga Fucus radicans and the flounder Platichthys solemdali. Both appear to have evolved in the Baltic basin and were only recognized as species in 2005 and 2018 respectively, having formerly been confused with more widespread relatives.[49][51] The tiny Copenhagen cockle (Parvicardium hauniense), a rare mussel, is sometimes considered endemic, but has now been recorded in the Mediterranean.[52] However, some consider non-Baltic records to be misidentifications of juvenile lagoon cockles (Cerastoderma glaucum).[53] Several widespread marine species have distinctive subpopulations in the Baltic Sea adapted to the low salinity, such as the Baltic Sea forms of the Atlantic herring and lumpsucker, which are smaller than the widespread forms in the North Atlantic.[40]
+
+A peculiar feature of the fauna is that it contains a number of glacial relict species, isolated populations of arctic species which have remained in the Baltic Sea since the last glaciation, such as the large isopod Saduria entomon, the Baltic subspecies of ringed seal, and the fourhorn sculpin. Some of these relicts are derived from glacial lakes, such as  Monoporeia affinis, which is a main element in the benthic fauna of the low-salinity Bothnian Bay.
+
+Cetaceans in Baltic Sea have been monitored by the ASCOBANS. Critically endangered populations of Atlantic white-sided dolphins and harbor porpoises inhabit the sea where white-colored porpoises have been recorded,[54] and occasionally oceanic and out-of-range species such as minke whales,[55] bottlenose dolphins,[56] beluga whales,[57] orcas,[58] and beaked whales[59] visit the waters. In recent years, very small, but with increasing rates, fin whales[60][61][62][63] and humpback whales migrate into Baltic sea including mother and calf pair.[64] Now extinct Atlantic grey whales (remains found from Gräsö along Bothnian Sea/southern Bothnian Gulf[65] and Ystad[66]) and eastern population of North Atlantic right whales that is facing functional extinction[67] once migrated into Baltic Sea.[68]
+
+Other notable megafauna include the basking sharks.[69]
+
+Satellite images taken in July 2010 revealed a massive algal bloom covering 377,000 square kilometres (146,000 sq mi) in the Baltic Sea. The area of the bloom extended from Germany and Poland to Finland. Researchers of the phenomenon have indicated that algal blooms have occurred every summer for decades. Fertilizer runoff from surrounding agricultural land has exacerbated the problem and led to increased eutrophication.[70]
+
+Approximately 100,000 km2 (38,610 sq mi) of the Baltic's seafloor (a quarter of its total area) is a variable dead zone. The more saline (and therefore denser) water remains on the bottom, isolating it from surface waters and the atmosphere. This leads to decreased oxygen concentrations within the zone. It is mainly bacteria that grow in it, digesting organic material and releasing hydrogen sulfide. Because of this large anaerobic zone, the seafloor ecology differs from that of the neighbouring Atlantic.
+
+Plans to artificially oxygenate areas of the Baltic that have experienced eutrophication have been proposed by the University of Gothenburg and Inocean AB. The proposal intends to use wind-driven pumps to inject oxygen (air) into waters at, or around, 130m below sea level.[71]
+
+After World War II, Germany had to be disarmed and large quantities of ammunition stockpiles were disposed directly into the Baltic Sea and the North Sea. Environmental experts and marine biologists warn that these ammunition dumps pose a major environmental threat with potentially life-threatening consequences to the health and safety of humans on the coastlines of these seas.[72]
+
+Construction of the Great Belt Bridge in Denmark (completed 1997) and the Øresund Bridge-Tunnel (completed 1999), linking Denmark with Sweden, provided a highway and railroad connection between Sweden and the Danish mainland (the Jutland Peninsula, precisely the Zealand). The undersea tunnel of the Øresund Bridge-Tunnel provides for navigation of large ships into and out of the Baltic Sea. The Baltic Sea is the main trade route for export of Russian petroleum. Many of the countries neighboring the Baltic Sea have been concerned about this, since a major oil leak in a seagoing tanker would be disastrous for the Baltic—given the slow exchange of water. The tourism industry surrounding the Baltic Sea is naturally concerned about oil pollution.
+
+Much shipbuilding is carried out in the shipyards around the Baltic Sea. The largest shipyards are at Gdańsk, Gdynia, and Szczecin, Poland; Kiel, Germany; Karlskrona and Malmö, Sweden; Rauma, Turku, and Helsinki, Finland; Riga, Ventspils, and Liepāja, Latvia; Klaipėda, Lithuania; and Saint Petersburg, Russia.
+
+There are several cargo and passenger ferries that operate on the Baltic Sea, such as Scandlines, Silja Line, Polferries, the Viking Line, Tallink, and Superfast Ferries.
+
+Piers
+
+
+
+Resort towns
+
+
+
+For the first time ever, all the sources of pollution around an entire sea were made subject to a single convention, signed in 1974 by the then seven Baltic coastal states. The 1974 Convention entered into force on 3 May 1980.
+
+In the light of political changes and developments in international environmental and maritime law, a new convention was signed in 1992 by all the states bordering on the Baltic Sea, and the European Community. After ratification the Convention entered into force on 17 January 2000. The Convention covers the whole of the Baltic Sea area, including inland waters and the water of the sea itself, as well as the seabed. Measures are also taken in the whole catchment area of the Baltic Sea to reduce land-based pollution. The Convention on the Protection of the Marine Environment of the Baltic Sea Area, 1992, entered into force on 17 January 2000.
+
+The governing body of the convention is the Helsinki Commission,[73] also known as HELCOM, or Baltic Marine Environment Protection Commission. The present contracting parties are Denmark, Estonia, the European Community, Finland, Germany, Latvia, Lithuania, Poland, Russia and Sweden.
+
+The ratification instruments were deposited by the European Community, Germany, Latvia and Sweden in 1994, by Estonia and Finland in 1995, by Denmark in 1996, by Lithuania in 1997, and by Poland and Russia in November 1999.

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+
+
+The Caspian Sea  is the world's largest inland body of water, variously classed as the world's largest lake or a full-fledged sea. It is an endorheic basin (a basin without outflows) located between Europe and Asia, to the east of the Caucasus Mountains and to the west of the broad steppe of Central Asia. The sea has a surface area of 371,000 km2 (143,200 sq mi) (excluding the detached lagoon of Garabogazköl) and a volume of 78,200 km3 (18,800 cu mi). It has a salinity of approximately 1.2% (12 g/l), about a third of the salinity of most seawater.  It is bounded by Kazakhstan to the northeast, Russia to the northwest, Azerbaijan to the west, Iran to the south, and Turkmenistan to the southeast. The Caspian Sea is home to a wide range of species and may be best known for its caviar and oil industries. Pollution from the oil industry and dams on rivers draining into the Caspian Sea have had negative effects on the organisms living in the sea.
+
+The wide and endorheic Caspian Sea has a north–south orientation and its main freshwater inflow, the Volga River, enters at the shallow north end. Two deep basins occupy its central and southern areas. These lead to horizontal differences in temperature, salinity, and ecology. The Caspian Sea spreads out over nearly 1,200 kilometres (750 mi) from north to south, with an average width of 320 km (200 mi). It covers a region of around 386,400 km2 (149,200 sq mi) and its surface is about 27 m (89 ft) below sea level. The sea bed in the southern part reaches as low as 1,023 m (3,356 ft) below sea level, which is the second lowest natural depression on Earth after Lake Baikal (−1,180 m or −3,870 ft). The ancient inhabitants of its coast perceived the Caspian Sea as an ocean, probably because of its saltiness and large size.
+
+The word Caspian is derived from the name of the Caspi, an ancient people who lived to the southwest of the sea in Transcaucasia.[2] Strabo wrote that "to the country of the Albanians belongs also the territory called Caspiane, which was named after the Caspian tribe, as was also the sea; but the tribe has now disappeared".[3] Moreover, the Caspian Gates, which is the name of a region in Iran's Tehran province, possibly indicates that they migrated to the south of the sea. The Iranian city of Qazvin shares the root of its name with that of the sea. In fact, the traditional Arabic name for the sea itself is Baḥr Qazwin (Sea of Qazvin).[4]
+
+In classical antiquity among Greeks and Persians it was called the Hyrcanian Ocean.[5] In Persian middle age, as well as in modern Iran, it is known as درياى خزر, Daryā-e Khazar, which was named after Khazars an ancient nomadic tribe in the region. it is also sometimes referred to as Mazandaran Sea (Persian: دریای مازندران‎) in Iran.[6]
+
+Some Turkic peoples refer to the lake as Khazar Sea. In Turkmen, the name is Hazar deňizi, in Azeri, it is Xəzər dənizi, and in modern Turkish, it is Hazar denizi. In all these cases, the second word simply means "sea", and the first word refers to the historical Khazars who had a large empire based to the north of the Caspian Sea between the 7th and 10th centuries. Some other Turkic ethnic groups refer to the lake as Caspian Sea. In Kazakh, where it is called Каспий теңізі, Kaspiy teñizi, in Kyrgyz: Каспий деңизи (Kaspiy deñizi), in Uzbek: Kaspiy dengizi.
+
+Renaissance European maps labelled it as Abbacuch Sea (Oronce Fine's 1531 world map), Mar de Bachu (Ortellius' 1570 map), or Mar de Sala (Mercator's 1569 map).
+
+Old Russian sources call it the Khvalyn or Khvalis Sea (Хвалынское море / Хвалисское море) after the name of Khwarezmia.[7] In modern Russian, it is called Каспи́йское мо́ре, Kaspiyskoye more.
+
+The Caspian Sea, like the Black Sea, is a remnant of the ancient Paratethys Sea. Its seafloor is, therefore, a standard oceanic basalt and not a continental granite body. It became landlocked about 5.5 million years ago due to tectonic uplift and a fall in sea level. During warm and dry climatic periods, the landlocked sea almost dried up, depositing evaporitic sediments like halite that were covered by wind-blown deposits and were sealed off as an evaporite sink when cool, wet climates refilled the basin. (Comparable evaporite beds underlie the Mediterranean.) Due to the current inflow of fresh water in the north, the Caspian Sea water is almost fresh in its northern portions, getting more brackish toward the south. It is most saline on the Iranian shore, where the catchment basin contributes little flow.[8] Currently, the mean salinity of the Caspian is one third that of Earth's oceans. The Garabogazköl embayment, which dried up when water flow from the main body of the Caspian was blocked in the 1980s but has since been restored, routinely exceeds oceanic salinity by a factor of 10.[9]
+
+The Caspian Sea is the largest inland body of water in the world and accounts for 40 to 44% of the total lacustrine waters of the world.[10] The coastlines of the Caspian are shared by Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan. The Caspian is divided into three distinct physical regions: the Northern, Middle, and Southern Caspian.[11] The Northern–Middle boundary is the Mangyshlak Threshold, which runs through Chechen Island and Cape Tiub-Karagan. The Middle–Southern boundary is the Apsheron Threshold, a sill of tectonic origin between the Eurasian continent and an oceanic remnant,[12] that runs through Zhiloi Island and Cape Kuuli.[13] The Garabogazköl Bay is the saline eastern inlet of the Caspian, which is part of Turkmenistan and at times has been a lake in its own right due to the isthmus that cuts it off from the Caspian.
+
+Differences between the three regions are dramatic. The Northern Caspian only includes the Caspian shelf,[14] and is very shallow; it accounts for less than 1% of the total water volume with an average depth of only 5–6 metres (16–20 ft). The sea noticeably drops off towards the Middle Caspian, where the average depth is 190 metres (620 ft).[13] The Southern Caspian is the deepest, with oceanic depths of over 1,000 metres (3,300 ft), greatly exceeding the depth of other regional seas, such as the Persian Gulf. The Middle and Southern Caspian account for 33% and 66% of the total water volume, respectively.[11] The northern portion of the Caspian Sea typically freezes in the winter, and in the coldest winters ice forms in the south as well.[15]
+
+Over 130 rivers provide inflow to the Caspian, with the Volga River being the largest. A second affluent, the Ural River, flows in from the north, and the Kura River flows into the sea from the west. In the past, the Amu Darya (Oxus) of Central Asia in the east often changed course to empty into the Caspian through a now-desiccated riverbed called the Uzboy River, as did the Syr Darya farther north. The Caspian also has several small islands; they are primarily located in the north and have a collective land area of roughly 2,000 km2 (770 sq mi). Adjacent to the North Caspian is the Caspian Depression, a low-lying region 27 metres (89 ft) below sea level. The Central Asian steppes stretch across the northeast coast, while the Caucasus mountains hug the western shore. The biomes to both the north and east are characterized by cold, continental deserts. Conversely, the climate to the southwest and south are generally warm with uneven elevation due to a mix of highlands and mountain ranges; the drastic changes in climate alongside the Caspian have led to a great deal of biodiversity in the region.[9]
+
+The Caspian Sea has numerous islands throughout, all of them near the coasts; none in the deeper parts of the sea. Ogurja Ada is the largest island. The island is 37 km (23 mi) long, with gazelles roaming freely on it. In the North Caspian, the majority of the islands are small and uninhabited, like the Tyuleniy Archipelago, an Important Bird Area (IBA), although some of them have human settlements.
+
+The Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, although it is not a freshwater lake.  It contains about 3.5 times more water, by volume, than all five of North America's Great Lakes combined. The Caspian was once part of the Tethys Ocean, but became landlocked about 5.5 million years ago due to plate tectonics.[10] The Volga River (about 80% of the inflow) and the Ural River discharge into the Caspian Sea, but it has no natural outflow other than by evaporation. Thus the Caspian ecosystem is a closed basin, with its own sea level history that is independent of the eustatic level of the world's oceans.
+
+The level of the Caspian has fallen and risen, often rapidly, many times over the centuries. Some Russian historians[who?] claim that a medieval rising of the Caspian, perhaps caused by the Amu Darya changing its inflow to the Caspian from the 13th century to the 16th century, caused the coastal towns of Khazaria, such as Atil, to flood. In 2004, the water level was 28 metres (92 feet) below sea level.
+
+Over the centuries, Caspian Sea levels have changed in synchrony with the estimated discharge of the Volga, which in turn depends on rainfall levels in its vast catchment basin. Precipitation is related to variations in the amount of North Atlantic depressions that reach the interior, and they in turn are affected by cycles of the North Atlantic oscillation. Thus levels in the Caspian Sea relate to atmospheric conditions in the North Atlantic, thousands of kilometres to the northwest.[citation needed]
+
+The last short-term sea-level cycle started with a sea-level fall of 3 m (10 ft) from 1929 to 1977, followed by a rise of 3 m (10 ft) from 1977 until 1995. Since then smaller oscillations have taken place.[16]
+
+A study by the Azerbaijan Academy of Sciences estimated that the level of the sea was dropping by more than six centimetres per year due to increased evaporation due to rising temperatures caused by climate change.[17]
+
+The Volga River, the largest in Europe, drains 20% of the European land area and is the source of 80% of the Caspian's inflow. Its lower reaches are heavily developed with numerous unregulated releases of chemical and biological pollutants. The UN Environment Programme warns that the Caspian "suffers from an enormous burden of pollution from oil extraction and refining, offshore oil fields, radioactive wastes from nuclear power plants and huge volumes of untreated sewage and industrial waste introduced mainly by the Volga River".[17]
+
+The magnitude of fossil fuel extraction and transport activity in the Caspian also poses a risk to the environment. The island of Vulf off Baku, for example, has suffered ecological damage as a result of the petrochemical industry; this has significantly decreased the number of species of marine birds in the area. Existing and planned oil and gas pipelines under the sea further increase the potential threat to the environment.[18]
+
+The rising level of the Caspian Sea between 1994 and 1996 reduced the number of habitats for rare species of aquatic vegetation. This has been attributed to a general lack of seeding material in newly formed coastal lagoons and water bodies.[citation needed]
+
+The Caspian turtle (Mauremys caspica), although found in neighboring areas, is a wholly freshwater species. The zebra mussel is native to the Caspian and Black Sea basins, but has become an invasive species elsewhere, when introduced. The area has given its name to several species, including the Caspian gull and the Caspian tern. The Caspian seal (Pusa caspica) is the only aquatic mammal and is endemic to the Caspian Sea, being one of very few seal species that live in inland waters, but it is different from the those inhabiting freshwaters due to the hydrological environment of the sea. A century ago the Caspian was home to more than one million seals. Today, fewer than 10% remain.[17]
+
+Archeological studies of Gobustan Rock Art have identified what may be dolphins[20] and porpoises,[21][22] or a certain species of beaked whales[23] and what may be a whaling scene indicates large baleen whales[24] likely being present in Caspian Sea at least until when the Caspian Sea ceased being a part of the ocean system or until the Quaternary or much more recent periods such as until the last glacial period or antiquity.[25] Although the rock art on Kichikdash Mountain is assumed to be of a dolphin[26] or of a beaked whale,[23] it might instead represent the famous beluga sturgeon due to its size (430 cm in length), but fossil records suggest certain ancestors of modern dolphins and whales, such as Macrokentriodon morani (bottlenose dolphins) and Balaenoptera sibbaldina (blue whales) were presumably larger than their present descendants. From the same artworks, auks, like Brunnich's Guillemot could also have been in the sea as well, and these petroglyphs suggest marine inflow between the current Caspian Sea and the Arctic Ocean or North Sea, or the Black Sea.[26] This is supported by the existences of current endemic, oceanic species such as lagoon cockles which was genetically identified to originate in Caspian/Black Seas regions.[24]
+
+The sea's basin (including associated waters such as rivers) has 160 native species and subspecies of fish in more than 60 genera.[19] About 62% of the species and subspecies are endemic, as are 4–6 genera (depending on taxonomic treatment). The lake proper has 115 natives, including 73 endemics (63.5%).[19] Among the more than 50 genera in the lake proper, 3–4 are endemic: Anatirostrum, Caspiomyzon, Chasar (often included in Ponticola) and Hyrcanogobius.[19] By far the most numerous families in the lake proper are gobies (35 species and subspecies), cyprinids (32) and clupeids (22). Two particularly rich genera are Alosa with 18 endemic species/subspecies and Benthophilus with 16 endemic species.[19] Other examples of endemics are four species of Clupeonella, Gobio volgensis, two Rutilus, three Sabanejewia, Stenodus leucichthys, two Salmo, two Mesogobius and three Neogobius.[19] Most non-endemic natives are either shared with the Black Sea basin or widespread Palearctic species such as crucian carp, Prussian carp, common carp, common bream, common bleak, asp, white bream, sunbleak, common dace, common roach, common rudd, European chub, sichel, tench, European weatherfish, wels catfish, northern pike, burbot, European perch and zander.[19] Almost 30 non-indigenous, introduced fish species have been reported from the Caspian Sea, but only a few have become established.[19]
+
+Six sturgeon species, the Russian, bastard, Persian, sterlet, starry and beluga, are native to the Caspian Sea.[19] The last of these is arguably the largest freshwater fish in the world. The sturgeon yield roe (eggs) that are processed into caviar. Overfishing has depleted a number of the historic fisheries.[27] In recent years, overfishing has threatened the sturgeon population to the point that environmentalists advocate banning sturgeon fishing completely until the population recovers. The high price of sturgeon caviar—more than 1,500 Azerbaijani manats[17] (US$880 as of April 2019[update]) per kilo—allows fishermen to afford bribes to ensure the authorities look the other way, making regulations in many locations ineffective.[28] Caviar harvesting further endangers the fish stocks, since it targets reproductive females.
+
+Many rare and endemic plant species of Russia are associated with the tidal areas of the Volga delta and riparian forests of the Samur River delta. The shoreline is also a unique refuge for plants adapted to the loose sands of the Central Asian Deserts. The principal limiting factors to successful establishment of plant species are hydrological imbalances within the surrounding deltas, water pollution, and various land reclamation activities. The water level change within the Caspian Sea is an indirect reason for which plants may not get established.
+
+These affect aquatic plants of the Volga Delta, such as Aldrovanda vesiculosa and the native Nelumbo caspica. About 11 plant species are found in the Samur River Delta, including the unique liana forests that date back to the Tertiary period.[citation needed]
+
+Reptiles native to the region include spur-thighed tortoise (Testudo graeca buxtoni) and Horsfield's tortoise.
+
+The history of the Caspian sea is divided into two parts: a Miocene stage, determined by tectonic events that correlate with the closing of the Tethys Sea, and a Pleistocene stage, that includes glaciation cycles and the creation of the present Volga River. During the first stage, the Tethys Sea had evolved into the Sarmatian Lake, that was created from the modern Black Sea and south Caspian, when the collision of the Arabian peninsula with Western Asia pushed up the Kopet Dag and Caucasus Mountains, setting definitive south and west boundaries to the Caspian basin. This orogeneic movement was continuous throughout the years, while Caspian was regularly disconnecting from the Black Sea. In the late Pontian, a mountain arch rose across the south basin and divided it in the Khachmaz and Lankaran Lakes (or early Balaxani). The period of restriction to the south basin was reversed during the Akchagylian, when the lake expanded to more than three times its present area and established the first of a series of contacts with the Black Sea and with Lake Aral. A recession of the Lake Akchagyl [ru] completed stage one.[31]
+
+The earliest hominid remains found around the Caspian Sea are from Dmanisi dating back to around 1.8 Ma and yielded a number of skeletal remains of Homo erectus or Homo ergaster. More later evidence for human occupation of the region came from a number of caves in Georgia and Azerbaijan such as Kudaro and Azykh Caves. There is evidence for Lower Palaeolithic human occupation south of the Caspian from western Alburz. These are Ganj Par and Darband Cave sites.
+
+Neanderthal remains also have been discovered at a cave site in Georgia. Discoveries in the Huto cave and the adjacent Kamarband cave, near the town of Behshahr, Mazandaran south of the Caspian in Iran, suggest human habitation of the area as early as 11,000 years ago.[32][33]
+
+The Caspian area is rich in energy resources. Oil wells were being dug in the region as early as the 10th century to reach oil "for use in everyday life, both for medicinal purposes and for heating and lighting in homes".[34][full citation needed] By the 16th century, Europeans were aware of the rich oil and gas deposits around the area. English traders Thomas Bannister and Jeffrey Duckett described the area around Baku as "a strange thing to behold, for there issueth out of the ground a marvelous quantity of oil, which serveth all the country to burn in their houses. This oil is black and is called nefte. There is also by the town of Baku, another kind of oil which is white and very precious [i.e., petroleum]."[35][full citation needed]
+
+Greeks also called it Hyrcanian/Hyrkanian Sea (Ancient Greek: Υρκανία θάλαττα[36] and Υρκανία θάλασσα[37]).
+
+In the 18th century, during the rule of Peter I the Great, Fedor I. Soimonov, hydrographer and pioneering explorer of the Caspian Sea charted the until then little known body of water. Soimonov drew a set of four maps and wrote Pilot of the Caspian Sea, the first report and modern maps of the Caspian, that were published in 1720 by the Russian Academy of Sciences.[38]
+
+Today, oil and gas platforms abound along the edges of the sea.[39]
+
+Countries on the Caspian region, such as Azerbaijan, Kazakhstan and Turkmenistan, illustrate the examples of natural-resource-based economies. A resource-based economy is defined as one where the natural resources, oil and gas, compose more than 10 percent of the particular country's GDP and 40 percent of exports.[40] All the Caspian region economies are highly dependent on the mineral wealth. The world energy markets were influenced by Azerbaijan and Kazakhstan, as they became strategically crucial in this sphere, thus attracting the largest share of FDI (foreign direct investment).
+
+Iran has an enormous energy potential based on several specific factors. It has reserves containing 137.5 billion bbl of crude oil, the second largest in the world, producing around four million bbl/day. Additionally, Iran has an estimated 988.4 trillion cubic feet of natural gas, around 16 percent of total world reserves, which makes it to play a key role in the global energy security equation.[41]
+
+Russia's economy ranks as the twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2015.[42] Russia's extensive mineral and energy resources are the largest such reserves in the world,[43] making it the second leading producer of oil and natural gas globally.[44]
+
+Caspian littoral states join efforts to develop infrastructure, tourism and trade in the region. The first Caspian Economic Forum was convened on August 12, 2019 in Turkmenistan and brought together representatives of Kazakhstan, Russia, Azerbaijan, Iran and Turkmenistan. The forum included several meetings of Caspian littoral countries’ ministers of economy and transport ministers.[45]
+
+The Caspian Sea region presently is a significant, but not major, supplier of crude oil to world markets, based upon estimates by BP Amoco and the U.S. Energy Information Administration, U.S. Department of Energy. The Caspian region produced an estimated 1.4–1.5 million barrels per day (bbls/day) including natural gas liquids in 2001, or 1.9% of total world output (table 1).3 More than a dozen non-Caspian countries each produce more than 1.5 million bbls/day. Caspian region production has been higher, but suffered during the collapse of the Soviet Union and the years following. Kazakhstan accounts for 55% and Azerbaijan for about 20% of current regional oil output.[46]
+
+The world's first offshore wells and machine-drilled wells were made in Bibi-Heybat Bay, near Baku, Azerbaijan. In 1873, exploration and development of oil began in some of the largest fields known to exist in the world at that time on the Absheron Peninsula near the villages of Balakhanli, Sabunchi, Ramana, and Bibi Heybat. Total recoverable reserves were more than 500 million tons. By 1900, Baku had more than 3,000 oil wells, 2,000 of which were producing at industrial levels. By the end of the 19th century, Baku became known as the "black gold capital", and many skilled workers and specialists flocked to the city.
+
+By the beginning of the 20th century, Baku was the centre of international oil industry. In 1920, when the Bolsheviks captured Azerbaijan, all private property – including oil wells and factories – was confiscated. Afterwards, the republic's entire oil industry came under the control of the Soviet Union. By 1941, Azerbaijan was producing a record 23.5 million tons of oil per year, and the Baku region supplied nearly 72 percent of all oil extracted in the entire Soviet Union.[34]
+
+In 1994, the "Contract of the Century" was signed, signalling the start of major international development of the Baku oil fields. The Baku–Tbilisi–Ceyhan pipeline, a major pipeline allowing Azerbaijan oil to flow straight to the Turkish Mediterranean port of Ceyhan, opened in 2006.
+
+The Vladimir Filanovsky field in the Russian section of the body of water was discovered for its wealth of oil in 2005. It is reportedly the largest discovery of oil in 25 years. It was announced in October 2016 that Lukoil would start production in this region.[47]
+
+Baku, which is the starting point of all sea routes of Azerbaijan, is the largest port of the Caspian Sea. Azerbaijan has access to the oceans along the Caspian Sea-Volga-Volga-Don Canal, and the Don-Sea of Azov. Along with the Volga-Don Canal, the Azerbaijani vessels have the opportunity to enter the world ocean through the Volga-Baltic and White Sea-Baltic canals. Moreover, oil tankers are being transported through the Caspian Sea. Baku Sea Trade Port and Caspian Shipping Company CJSC, have a big role in the sea transportation of Azerbaijan. The Caspian Sea Shipping Company CJSC, along with the transport fleet, also includes a specialized fleet and shipyards. The transport fleet consists of 51 vessels, including 20 tankers, 13 ferries, 15 universal dry cargo vessels, 2 Ro-Ro vessels, as well as 1 technical vessel and 1 floating workshop. The specialized fleet includes 210 vessels, including 20 cranes, 25 towing and supplying vehicles, 26 passenger, two pipe-laying, six fire-fighting, seven engineering-geological, two diving and 88 auxiliary vessels.[48]
+
+The Caspian Sea Shipping Company of Azerbaijan, which acts as a liaison in the Transport Corridor Europe-Caucasus-Asia (TRACECA), simultaneously with the transportation of cargo and passengers in the Trans-Caspian direction, also performs work to fully ensure the processes of oil and gas production at sea. This activity has a rich history. The development of the shipping industry in Azerbaijan is closely connected with the formation and progress of the oil industry. In the 19th century, the sharp increase in oil production in Baku gave a huge impetus to the development of shipping in the Caspian Sea, and as a result, there was a need to create fundamentally new floating facilities for the transportation of oil and oil products.[49]
+
+Many of the islands along the Azerbaijani coast continue to hold significant geopolitical and economic importance because of the potential oil reserves found nearby. Bulla Island, Pirallahı Island, and Nargin, which is still used as a former Soviet base and is the largest island in the Baku bay, all hold oil reserves.
+
+The collapse of the Soviet Union and subsequent opening of the region has led to an intense investment and development scramble by international oil companies. In 1998, Dick Cheney commented that "I can't think of a time when we've had a region emerge as suddenly to become as strategically significant as the Caspian."[50]
+
+A key problem to further development in the region is the status of the Caspian Sea and the establishment of the water boundaries among the five littoral states. The current disputes along Azerbaijan's maritime borders with Turkmenistan and Iran could potentially affect future development plans.
+
+Much controversy currently exists over the proposed Trans-Caspian oil and gas pipelines. These projects would allow Western markets easier access to Kazakh oil and, potentially, Uzbek and Turkmen gas as well. Russia officially opposes the project on environmental grounds.[51] However, analysts note that the pipelines would bypass Russia completely, thereby denying the country valuable transit fees, as well as destroying its current monopoly on westward-bound hydrocarbon exports from the region.[51] Recently, both Kazakhstan and Turkmenistan have expressed their support for the Trans-Caspian Pipeline.[52]
+
+U.S. diplomatic cables disclosed by WikiLeaks revealed that BP covered up a gas leak and blowout incident in September 2008 at an operating gas field in the Azeri-Chirag-Guneshi area of the Azerbaijan Caspian Sea.[53][54]
+
+Five states are located along about 6500 km of Caspian coastline. The length of the coastline of these countries:[55]
+
+The Caspian Sea is the world's largest salt lake. Its length from north to south is 1,174 km, average width is 326 km, and total area is 375,000 km2. Water depth in the middle of the Caspian Sea ranges up to 788 m and in the southern part, up to 1,025 m. It has no outlet, and although the surface level of water fluctuates, it averages about 25 m below sea level according to recent measurements. Total area of the FSU portion of the Caspian Sea is 322,000 km2, including the shelf zone. To a depth of 200 m, the area is 240,000 km2.[57]
+
+As of 2000[update], negotiations related to the demarcation of the Caspian Sea had been going on for nearly a decade among the states bordering the Caspian – Azerbaijan, Russia, Kazakhstan, Turkmenistan, and Iran. The status of the Caspian Sea[58] is the key problem. Access to mineral resources (oil and natural gas), access for fishing, and access to international waters (through Russia's Volga river and the canals connecting it to the Black Sea and Baltic Sea) all depend upon the outcomes of negotiations. Access to the Volga River is particularly important for the landlocked states of Azerbaijan, Kazakhstan, and Turkmenistan. This concerns Russia, because the potential traffic would use its inland waterways. If a body of water is labelled as a sea, then there would be some precedents and international treaties obliging the granting of access permits to foreign vessels. If a body of water is labelled merely as a lake, then there are no such obligations. Environmental issues are also somewhat connected to the status and borders issue.
+
+All five Caspian littoral states maintain naval forces on the sea.[59]
+
+According to a treaty signed between Iran and the Soviet Union, the Caspian Sea is technically a lake and was divided into two sectors (Iranian and Soviet), but the resources (then mainly fish) were commonly shared. The line between the two sectors was considered an international border in a common lake, like Lake Albert. The Soviet sector was sub-divided into the four littoral republics' administrative sectors.
+
+Russia, Kazakhstan, and Azerbaijan have bilateral agreements with each other based on median lines. Because of their use by the three nations, median lines seem to be the most likely method of delineating territory in future agreements. However, Iran insists on a single, multilateral agreement between the five nations (as this is the only way for it to achieve a one-fifth share of the sea). Azerbaijan is at odds with Iran over some oil fields that both states claim. Occasionally, Iranian patrol boats have fired at vessels sent by Azerbaijan for exploration into the disputed region. There are similar tensions between Azerbaijan and Turkmenistan (the latter claims that the former has pumped more oil than agreed from a field, recognized by both parties as shared).
+
+The Caspian littoral states' meeting in 2007 signed an agreement that bars any ship not flying the national flag of a littoral state from entering the sea.[60]
+
+Negotiations among the five littoral states have been ongoing, amidst ebbs and flows, for the past 20 years, with some degree of progress being made at the fourth Caspian Summit held in Astrakhan in 2014.[61]
+
+The Caspian Summit is a head of state-level meeting of the five littoral states.[62] The fifth Caspian Summit took place on August 12, 2018 in the Kazakh port city of Aktau .[62] The five leaders signed the ‘Convention on the Legal Status of the Caspian Sea’.[63]
+
+Representatives of the Caspian littoral states held a meeting in the capital of Kazakhstan on September 28, 2018 as a follow-up to the Aktau Summit. The conference was hosted by the Kazakh Ministry of Investment and Development. The participants in the meeting agreed to host an investment forum for the Caspian region every two years.[64]
+
+The five littoral states build consensus on legally binding governance of the Caspian Sea through Special Working Groups of a Convention on the Legal Status of the Caspian Sea.[65] In advance of a Caspian Summit, 51st Special Working Group took place in Astana in May 2018 and found consensus on multiple agreements: Agreements on cooperation in the field of transport; trade and economic cooperation; prevention of incidents on the sea; combating terrorism; fighting against organized crime; and border security cooperation.[66]
+
+The convention grants jurisdiction over 24 km (15 mi) of territorial waters to each neighboring country, plus an additional 16 km (10 mi) of exclusive fishing rights on the surface, while the rest is international waters. The seabed, on the other hand, remains undefined, subject to bilateral agreements between countries. Thus, the Caspian Sea is legally neither fully a sea nor a lake.[67]
+
+While the convention addresses caviar production, oil and gas extraction, and military uses, it does not touch on environmental issues.[17]
+
+UNECE recognizes several rivers that cross international borders which flow into the Caspian Sea.[68]
+These are:
+
+Although the Caspian Sea is endorheic, its main tributary, the Volga, is connected by important shipping canals with the Don River (and thus the Black Sea) and with the Baltic Sea, with branch canals to Northern Dvina and to the White Sea.
+
+Another Caspian tributary, the Kuma River, is connected by an irrigation canal with the Don basin as well.
+
+Several scheduled ferry services (including train ferries) operate on the Caspian Sea, including:
+
+The ferries are mostly used for cargo; only the Baku–Aktau and Baku–Türkmenbaşy routes accept passengers.
+
+As an endorheic basin, the Caspian Sea basin has no natural connection with the ocean. Since the medieval period, traders reached the Caspian via a number of portages that connected the Volga and its tributaries with the Don River (which flows into the Sea of Azov) and various rivers that flow into the Baltic Sea. Primitive canals connecting the Volga Basin with the Baltic were constructed as early as the early 18th century. Since then, a number of canal projects have been completed.
+
+The two modern canal systems that connect the Volga Basin, and hence the Caspian Sea, with the ocean are the Volga–Baltic Waterway and the Volga–Don Canal.
+
+The proposed Pechora–Kama Canal was a project that was widely discussed between the 1930s and 1980s. Shipping was a secondary consideration. Its main goal was to redirect some of the water of the Pechora River (which flows into the Arctic Ocean) via the Kama River into the Volga. The goals were both irrigation and the stabilization of the water level in the Caspian, which was thought to be falling dangerously fast at the time. During 1971, some peaceful nuclear construction experiments were carried out in the region by the U.S.S.R.
+
+In June 2007, in order to boost his oil-rich country's access to markets, Kazakhstan's President Nursultan Nazarbayev proposed a 700-kilometre (435-mile) link between the Caspian Sea and the Black Sea. It is hoped that the "Eurasia Canal" (Manych Ship Canal) would transform landlocked Kazakhstan and other Central Asian countries into maritime states, enabling them to significantly increase trade volume. Although the canal would traverse Russian territory, it would benefit Kazakhstan through its Caspian Sea ports. The most likely route for the canal, the officials at the Committee on Water Resources at Kazakhstan's Agriculture Ministry say, would follow the Kuma–Manych Depression, where currently a chain of rivers and lakes is already connected by an irrigation canal (the Kuma–Manych Canal). Upgrading the Volga–Don Canal would be another option.[69]

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+Wednesday is the day of the week between Tuesday and Thursday.  According to international standard ISO 8601 it is the third day of the week. In countries that have Friday as their holiday and in some Muslim countries, Wednesday would be the fifth day of the week. In countries that use the Sunday-first convention and in the Jewish Hebrew calendar Wednesday is defined as the fourth day of the week. The name is derived from Old English Wōdnesdæg and Middle English Wednesdei, "day of Woden", reflecting the religion practiced by the Anglo-Saxons, a variation of the Norse god Odin. In some other languages, such as the French mercredi or Italian mercoledì, the day's name is a calque of dies Mercurii "day of Mercury".
+
+Wednesday is in the middle of the common Western five-day workweek that starts on Monday and finishes on Friday.
+
+The name Wednesday continues Middle English Wednesdei. Old English still had wōdnesdæg, which would be continued as *Wodnesday  (but Old Frisian has an attested wednesdei).
+By the early 13th century, the i-mutated form was introduced unetymologically[clarification needed].
+
+The name is a calque of the Latin dies Mercurii "day of Mercury", reflecting the fact that the Germanic god Woden (Wodanaz or Odin) during the Roman era was interpreted as "Germanic Mercury".
+
+The Latin name dates to the late 2nd or early 3rd century. It is a calque of Greek ἡμέρα Ἕρμου (heméra Hérmou), a term first attested, together with the system of naming the seven weekdays after the seven classical planets, in the Anthologiarum by Vettius Valens (c. AD 170).
+
+The Latin name is reflected directly in the weekday name in most modern Romance languages: Mércuris (Sardinian), mercredi (French), mercoledì (Italian), miércoles (Spanish), miercuri (Romanian), dimecres (Catalan), Marcuri or Mercuri (Corsican), Mèrcore (Venetian). In Welsh it is Dydd Mercher, meaning Mercury's Day.
+
+The Dutch name for the day, woensdag, has the same etymology as English Wednesday; it comes from Middle Dutch wodenesdag, woedensdag ("Wodan's day").
+
+The German name for the day, Mittwoch (literally: "mid-week"), replaced the former name Wodenstag ("Wodan's day") in the 10th century. (Similarly, the Yiddish word for Wednesday is מיטוואך (mitvokh), meaning and sounding a lot like the German word it came from.)
+
+Most Slavic languages follow this pattern and use derivations of "the middle" (Belarusian серада serada, Bulgarian сряда sryada, Croatian srijeda, Czech středa, Macedonian среда sreda, Polish środa, Russian среда sredá, Serbian среда/sreda or cриједа/srijeda, Slovak streda, Slovene sreda, Ukrainian середа sereda). 
+The Finnish name is Keskiviikko ("middle of the week"), as is the Icelandic name: Miðvikudagur, and the Faroese name: Mikudagur ("Mid-week day").  Some dialects of Faroese have Ónsdagur, though, which shares etymology with Wednesday. Danish, Norwegian, Swedish Onsdag, ("Ons-dag" = Oden's/Odin's dag/day).
+
+In Japanese, the word for Wednesday is 水曜日(sui youbi), meaning 'water day' and is associated with 水星 (suisei): Mercury (the planet), literally meaning "water star". Similarly, in Korean the word Wednesday is 수요일 (su yo il), also meaning water day.
+
+In most of the languages of India, the word for Wednesday is Budhavāra — vāra meaning day and Budha being the planet Mercury.
+
+In Armenian (Չորեքշաբթի—chorekshabti), Georgian  (ოთხშაბათი—otkhshabati), Turkish (Çarşamba), and Tajik (Chorshanbiyev) languages the word literally means as "four (days) from Saturday" originating from Persian (چهارشنبه—Cheharshanbeh).
+
+Portuguese uses the word quarta-feira, meaning "fourth day", while in Greek the word is Tetarti (Τετάρτη) meaning simply "fourth". Similarly, Arabic أربعاء‎ means "fourth", Hebrew רביעי means "fourth", and Persian چهارشنبه‎ means "fourth day". Yet the name for the day in Estonian kolmapäev, Lithuanian trečiadienis, and Latvian trešdiena means "third day" while in Mandarin Chinese 星期三 (xīngqīsān), means "day three", as Sunday is unnumbered.
+
+The Creation narrative in the Hebrew Bible places the creation of the Sun and Moon on "the fourth day" of the divine workweek.
+
+Quakers traditionally referred to Wednesday as "Fourth Day" to avoid the pagan associations with the name "Wednesday",[1] or in keeping with the practice of treating each day as equally divine.
+
+The Eastern Orthodox Church observes Wednesday (as well as Friday) as a fast day throughout the year (with the exception of several fast-free periods during the year). Fasting on Wednesday and Fridays entails abstinence from meat or meat products (i.e., four-footed animals), poultry and dairy products. Unless a feast day occurs on a Wednesday, the Orthodox also abstain from fish, from using oil in their cooking and from alcoholic beverages (there is some debate over whether abstention from oil involves all cooking oil or only olive oil). For the Orthodox, Wednesdays and Fridays throughout the year commemorate the betrayal of Jesus (Wednesday) and the Crucifixion of Christ (Friday). There are hymns in the Octoekhos which reflect this liturgically.  These include special Theotokia (hymns to the Mother of God) called Stavrotheotokia ("Cross-Theotokia"). The dismissal at the end of services on Wednesday begins with these words: "May Christ our true God, through the power of the precious and life-giving cross...."
+
+In Irish and Scottish Gaelic, the name for Wednesday also refers to fasting, as it is Dé Céadaoin in Irish Gaelic and Di-Ciadain in Scottish Gaelic, which comes from chéad, "first" and aoine, "fasting" which means "first day of fasting".[2]
+
+In American culture many Catholic and Protestant churches schedule study or prayer meetings on Wednesday nights. The sports calendar in many American public schools reflects this, reserving Mondays and Thursdays for girls' games and Tuesdays and Fridays for boys' games while generally avoiding events on Wednesday evening.
+
+In the Catholic devotion of the Holy Rosary, the glorious mysteries are meditated on Wednesday and also Sunday throughout the year.
+
+Wednesday is the day of the week devoted by the Catholic tradition to St. Joseph.
+
+In Hindu mythology, Budha is the god of Mercury (planet), mid-week Wednesday, and of Merchants and merchandise.  According to the Thai solar calendar, the color associated with Wednesday is green.[3]
+
+In the folk rhyme "Wednesday's child is full of woe", reciting the days of the week, Solomon Grundy was 'Married on Wednesday.' In Winnie the Pooh and the Blustery Day, the disagreeable nature of the weather is attributed to it being "Winds-Day" (a play on "Wednesday"). In Richard Brautigan's In Watermelon Sugar Wednesday is the day when the sun shines grey.[full citation needed] Wednesday Friday Addams is a member of the fictional family The Addams Family. Her name is derived from the idea that Wednesday's child is full of woe. Additionally, Wednesday sometimes appears as a character's name in literary works. These include Thursday's fictions by Richard James Allen and Neil Gaiman's novel American Gods. In the 1945 John Steinbeck novel Sweet Thursday, the titular day is preceded by "Lousy Wednesday".
+
+Wednesday is sometimes informally referred to as "hump day" in North America, a reference to the fact that Wednesday is the middle day—or "hump"—of a typical work week.[4][5]
+
+The astrological sign of the planet Mercury, ☿, represents Wednesday—Dies Mercurii to the Romans, it had similar names in Latin-derived languages, such as the Italian mercoledì (dì means "day"), the French mercredi, and the Spanish miércoles. In English, this became "Woden's Day", since the Roman god Mercury was identified by Woden in Northern Europe and it is especially aligned by the astrological signs of Gemini and Virgo. Wednesday is one of the only three days aside from Neptune and Pluto to be associated by another planet, which is Uranus.[citation needed]

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+Mercury usually refers to:
+
+Mercury may also refer to:
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+For vehicles, see § Vehicles, below

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+Mercury usually refers to:
+
+Mercury may also refer to:
+
+For vehicles, see § Vehicles, below

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+
+
+
+
+Mercury is the smallest and innermost planet in the Solar System. Its orbit around the Sun takes 87.97 days, the shortest of all the planets in the Solar System. It is named after the Roman deity Mercury, the messenger of the gods.
+
+Like Venus, Mercury orbits the Sun within Earth's orbit as an inferior planet, and its apparent distance from the Sun as viewed from Earth never exceeds 28°. This proximity to the Sun means the planet can only be seen near the western horizon after sunset or eastern horizon before sunrise, usually in twilight. At this time, it may appear as a bright star-like object, but is often far more difficult to observe than Venus. The planet telescopically displays the complete range of phases, similar to Venus and the Moon, as it moves in its inner orbit relative to Earth, which recurs over its synodic period of approximately 116 days.
+
+Mercury rotates in a way that is unique in the Solar System. It is tidally locked with the Sun in a 3:2 spin–orbit resonance,[16] meaning that relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around the Sun.[a][17] As seen from the Sun, in a frame of reference that rotates with the orbital motion, it appears to rotate only once every two Mercurian years. An observer on Mercury would therefore see only one day every two Mercurian years.
+
+Mercury's axis has the smallest tilt of any of the Solar System's planets (about ​1⁄30 degree). Its orbital eccentricity is the largest of all known planets in the Solar System;[b] at perihelion, Mercury's distance from the Sun is only about two-thirds (or 66%) of its distance at aphelion. Mercury's surface appears heavily cratered and is similar in appearance to the Moon's, indicating that it has been geologically inactive for billions of years. Having almost no atmosphere to retain heat, it has surface temperatures that vary diurnally more than on any other planet in the Solar System, ranging from 100 K (−173 °C; −280 °F) at night to 700 K (427 °C; 800 °F) during the day across the equatorial regions.[18] The polar regions are constantly below 180 K (−93 °C; −136 °F). The planet has no known natural satellites.
+
+Two spacecraft have visited Mercury: Mariner 10 flew by in 1974 and 1975; and MESSENGER, launched in 2004, orbited Mercury over 4,000 times in four years before exhausting its fuel and crashing into the planet's surface on April 30, 2015.[19][20][21] The BepiColombo spacecraft is planned to arrive at Mercury in 2025.
+
+Mercury appears to have a solid silicate crust and mantle overlying a solid, iron sulfide outer core layer, a deeper liquid core layer, and a solid inner core.[22][23]
+
+Mercury is one of four terrestrial planets in the Solar System, and is a rocky body like Earth. It is the smallest planet in the Solar System, with an equatorial radius of 2,439.7 kilometres (1,516.0 mi).[3] Mercury is also smaller—albeit more massive—than the largest natural satellites in the Solar System, Ganymede and Titan. Mercury consists of approximately 70% metallic and 30% silicate material.[24] Mercury's density is the second highest in the Solar System at 5.427 g/cm3, only slightly less than Earth's density of 5.515 g/cm3.[3] If the effect of gravitational compression were to be factored out from both planets, the materials of which Mercury is made would be denser than those of Earth, with an uncompressed density of 5.3 g/cm3 versus Earth's 4.4 g/cm3.[25]
+
+Mercury's density can be used to infer details of its inner structure. Although Earth's high density results appreciably from gravitational compression, particularly at the core, Mercury is much smaller and its inner regions are not as compressed. Therefore, for it to have such a high density, its core must be large and rich in iron.[26]
+
+Geologists estimate that Mercury's core occupies about 55% of its volume; for Earth this proportion is 17%. Research published in 2007 suggests that Mercury has a molten core.[27][28] Surrounding the core is a 500–700 km (310–430 mi) mantle consisting of silicates.[29][30] Based on data from the Mariner 10 mission and Earth-based observation, Mercury's crust is estimated to be 35 km (22 mi) thick.[31] One distinctive feature of Mercury's surface is the presence of numerous narrow ridges, extending up to several hundred kilometers in length. It is thought that these were formed as Mercury's core and mantle cooled and contracted at a time when the crust had already solidified.[32]
+
+Mercury's core has a higher iron content than that of any other major planet in the Solar System, and several theories have been proposed to explain this. The most widely accepted theory is that Mercury originally had a metal–silicate ratio similar to common chondrite meteorites, thought to be typical of the Solar System's rocky matter, and a mass approximately 2.25 times its current mass.[33] Early in the Solar System's history, Mercury may have been struck by a planetesimal of approximately 1/6 that mass and several thousand kilometers across.[33] The impact would have stripped away much of the original crust and mantle, leaving the core behind as a relatively major component.[33] A similar process, known as the giant impact hypothesis, has been proposed to explain the formation of the Moon.[33]
+
+Alternatively, Mercury may have formed from the solar nebula before the Sun's energy output had stabilized. It would initially have had twice its present mass, but as the protosun contracted, temperatures near Mercury could have been between 2,500 and 3,500 K and possibly even as high as 10,000 K.[34] Much of Mercury's surface rock could have been vaporized at such temperatures, forming an atmosphere of "rock vapor" that could have been carried away by the solar wind.[34]
+
+A third hypothesis proposes that the solar nebula caused drag on the particles from which Mercury was accreting, which meant that lighter particles were lost from the accreting material and not gathered by Mercury.[35] Each hypothesis predicts a different surface composition, and there are two space missions set to make observations. MESSENGER, which ended in 2015, found higher-than-expected potassium and sulfur levels on the surface, suggesting that the giant impact hypothesis and vaporization of the crust and mantle did not occur because potassium and sulfur would have been driven off by the extreme heat of these events.[36] BepiColombo, which will arrive at Mercury in 2025, will make observations to test these hypotheses.[37] The findings so far would seem to favor the third hypothesis; however, further analysis of the data is needed.[38]
+
+Mercury's surface is similar in appearance to that of the Moon, showing extensive mare-like plains and heavy cratering, indicating that it has been geologically inactive for billions of years. Because knowledge of Mercury's geology had been based only on the 1975 Mariner 10 flyby and terrestrial observations, it is the least understood of the terrestrial planets.[28] As data from MESSENGER orbiter are processed, this knowledge will increase. For example, an unusual crater with radiating troughs has been discovered that scientists called "the spider".[39] It was later named Apollodorus.[40]
+
+Albedo features are areas of markedly different reflectivity, as seen by telescopic observation. Mercury has dorsa (also called "wrinkle-ridges"), Moon-like highlands, montes (mountains), planitiae (plains), rupes (escarpments), and valles (valleys).[41][42]
+
+Names for features on Mercury come from a variety of sources. Names coming from people are limited to the deceased. Craters are named for artists, musicians, painters, and authors who have made outstanding or fundamental contributions to their field. Ridges, or dorsa, are named for scientists who have contributed to the study of Mercury. Depressions or fossae are named for works of architecture. Montes are named for the word "hot" in a variety of languages. Plains or planitiae are named for Mercury in various languages. Escarpments or rupēs are named for ships of scientific expeditions. Valleys or valles are named for abandoned cities, towns, or settlements of antiquity.[43]
+
+Mercury was heavily bombarded by comets and asteroids during and shortly following its formation 4.6 billion years ago, as well as during a possibly separate subsequent episode called the Late Heavy Bombardment that ended 3.8 billion years ago.[44] During this period of intense crater formation, Mercury received impacts over its entire surface,[42] facilitated by the lack of any atmosphere to slow impactors down.[45] During this time Mercury was volcanically active; basins such as the Caloris Basin were filled by magma, producing smooth plains similar to the maria found on the Moon.[46][47]
+
+Data from the October 2008 flyby of MESSENGER gave researchers a greater appreciation for the jumbled nature of Mercury's surface. Mercury's surface is more heterogeneous than either Mars's or the Moon's, both of which contain significant stretches of similar geology, such as maria and plateaus.[48]
+
+Craters on Mercury range in diameter from small bowl-shaped cavities to multi-ringed impact basins hundreds of kilometers across. They appear in all states of degradation, from relatively fresh rayed craters to highly degraded crater remnants. Mercurian craters differ subtly from lunar craters in that the area blanketed by their ejecta is much smaller, a consequence of Mercury's stronger surface gravity.[49] According to IAU rules, each new crater must be named after an artist that was famous for more than fifty years, and dead for more than three years, before the date the crater is named.[50]
+
+The largest known crater is Caloris Basin, with a diameter of 1,550 km.[51] The impact that created the Caloris Basin was so powerful that it caused lava eruptions and left a concentric ring over 2 km tall surrounding the impact crater. At the antipode of the Caloris Basin is a large region of unusual, hilly terrain known as the "Weird Terrain". One hypothesis for its origin is that shock waves generated during the Caloris impact traveled around Mercury, converging at the basin's antipode (180 degrees away). The resulting high stresses fractured the surface.[52] Alternatively, it has been suggested that this terrain formed as a result of the convergence of ejecta at this basin's antipode.[53]
+
+Overall, about 15 impact basins have been identified on the imaged part of Mercury. A notable basin is the 400 km wide, multi-ring Tolstoj Basin that has an ejecta blanket extending up to 500 km from its rim and a floor that has been filled by smooth plains materials. Beethoven Basin has a similar-sized ejecta blanket and a 625 km diameter rim.[49] Like the Moon, the surface of Mercury has likely incurred the effects of space weathering processes, including Solar wind and micrometeorite impacts.[54]
+
+There are two geologically distinct plains regions on Mercury.[49][55] Gently rolling, hilly plains in the regions between craters are Mercury's oldest visible surfaces,[49] predating the heavily cratered terrain. These inter-crater plains appear to have obliterated many earlier craters, and show a general paucity of smaller craters below about 30 km in diameter.[55]
+
+Smooth plains are widespread flat areas that fill depressions of various sizes and bear a strong resemblance to the lunar maria. Notably, they fill a wide ring surrounding the Caloris Basin. Unlike lunar maria, the smooth plains of Mercury have the same albedo as the older inter-crater plains. Despite a lack of unequivocally volcanic characteristics, the localisation and rounded, lobate shape of these plains strongly support volcanic origins.[49] All the smooth plains of Mercury formed significantly later than the Caloris basin, as evidenced by appreciably smaller crater densities than on the Caloris ejecta blanket.[49] The floor of the Caloris Basin is filled by a geologically distinct flat plain, broken up by ridges and fractures in a roughly polygonal pattern. It is not clear whether they are volcanic lavas induced by the impact, or a large sheet of impact melt.[49]
+
+One unusual feature of Mercury's surface is the numerous compression folds, or rupes, that crisscross the plains. As Mercury's interior cooled, it contracted and its surface began to deform, creating wrinkle ridges and lobate scarps associated with thrust faults. The scarps can reach lengths of 1000 km and heights of 3 km.[56] These compressional features can be seen on top of other features, such as craters and smooth plains, indicating they are more recent.[57] Mapping of the features has suggested a total shrinkage of Mercury's radius in the range of ~1 to 7 km.[58] Small-scale thrust fault scarps have been found, tens of meters in height and with lengths in the range of a few km, that appear to be less than 50 million years old, indicating that compression of the interior and consequent surface geological activity continue to the present.[56][58]
+
+The Lunar Reconnaissance Orbiter discovered that similar small thrust faults exist on the Moon.
+
+Images obtained by MESSENGER have revealed evidence for pyroclastic flows on Mercury from low-profile shield volcanoes.[59][60][61] MESSENGER data has helped identify 51 pyroclastic deposits on the surface,[62] where 90% of them are found within impact craters.[62] A study of the degradation state of the impact craters that host pyroclastic deposits suggests that pyroclastic activity occurred on Mercury over a prolonged interval.[62]
+
+A "rimless depression" inside the southwest rim of the Caloris Basin consists of at least nine overlapping volcanic vents, each individually up to 8 km in diameter. It is thus a "compound volcano".[63] The vent floors are at a least 1 km below their brinks and they bear a closer resemblance to volcanic craters sculpted by explosive eruptions or modified by collapse into void spaces created by magma withdrawal back down into a conduit.[63] Scientists could not quantify the age of the volcanic complex system, but reported that it could be of the order of a billion years.[63]
+
+The surface temperature of Mercury ranges from 100 to 700 K (−173 to 427 °C; −280 to 800 °F)[18] at the most extreme places: 0°N, 0°W, or 180°W. It never rises above 180 K at the poles,[12]
+due to the absence of an atmosphere and a steep temperature gradient between the equator and the poles. The subsolar point reaches about 700 K during perihelion (0°W or 180°W), but only 550 K at aphelion (90° or 270°W).[65]
+On the dark side of the planet, temperatures average 110 K.[12][66]
+The intensity of sunlight on Mercury's surface ranges between 4.59 and 10.61 times the solar constant (1,370 W·m−2).[67]
+
+Although the daylight temperature at the surface of Mercury is generally extremely high, observations strongly suggest that ice (frozen water) exists on Mercury. The floors of deep craters at the poles are never exposed to direct sunlight, and temperatures there remain below 102 K; far lower than the global average.[68] Water ice strongly reflects radar, and observations by the 70-meter Goldstone Solar System Radar and the VLA in the early 1990s revealed that there are patches of high radar reflection near the poles.[69] Although ice was not the only possible cause of these reflective regions, astronomers think it was the most likely.[70]
+
+The icy regions are estimated to contain about 1014–1015 kg of ice,[71] and may be covered by a layer of regolith that inhibits sublimation.[72] By comparison, the Antarctic ice sheet on Earth has a mass of about 4×1018 kg, and Mars's south polar cap contains about 1016 kg of water.[71] The origin of the ice on Mercury is not yet known, but the two most likely sources are from outgassing of water from the planet's interior or deposition by impacts of comets.[71]
+
+Mercury is too small and hot for its gravity to retain any significant atmosphere over long periods of time; it does have a tenuous surface-bounded exosphere[73] containing hydrogen, helium, oxygen, sodium, calcium, potassium and others at a surface pressure of less than approximately 0.5 nPa (0.005 picobars).[14] This exosphere is not stable—atoms are continuously lost and replenished from a variety of sources. Hydrogen atoms and helium atoms probably come from the solar wind, diffusing into Mercury's magnetosphere before later escaping back into space. Radioactive decay of elements within Mercury's crust is another source of helium, as well as sodium and potassium. MESSENGER found high proportions of calcium, helium, hydroxide, magnesium, oxygen, potassium, silicon and sodium. Water vapor is present, released by a combination of processes such as: comets striking its surface, sputtering creating water out of hydrogen from the solar wind and oxygen from rock, and sublimation from reservoirs of water ice in the permanently shadowed polar craters. The detection of high amounts of water-related ions like O+, OH−, and H3O+ was a surprise.[74][75] Because of the quantities of these ions that were detected in Mercury's space environment, scientists surmise that these molecules were blasted from the surface or exosphere by the solar wind.[76][77]
+
+Sodium, potassium and calcium were discovered in the atmosphere during the 1980–1990s, and are thought to result primarily from the vaporization of surface rock struck by micrometeorite impacts[78] including presently from Comet Encke.[79] In 2008, magnesium was discovered by MESSENGER.[80] Studies indicate that, at times, sodium emissions are localized at points that correspond to the planet's magnetic poles. This would indicate an interaction between the magnetosphere and the planet's surface.[81]
+
+On November 29, 2012, NASA confirmed that images from MESSENGER had detected that craters at the north pole contained water ice. MESSENGER's principal investigator Sean Solomon is quoted in The New York Times estimating the volume of the ice to be large enough to "encase Washington, D.C., in a frozen block two and a half miles deep".[64][c]
+
+Despite its small size and slow 59-day-long rotation, Mercury has a significant, and apparently global, magnetic field. According to measurements taken by Mariner 10, it is about 1.1% the strength of Earth's. The magnetic-field strength at Mercury's equator is about 300 nT.[82][83] Like that of Earth, Mercury's magnetic field is dipolar.[81] Unlike Earth's, Mercury's poles are nearly aligned with the planet's spin axis.[84] Measurements from both the Mariner 10 and MESSENGER space probes have indicated that the strength and shape of the magnetic field are stable.[84]
+
+It is likely that this magnetic field is generated by a dynamo effect, in a manner similar to the magnetic field of Earth.[85][86] This dynamo effect would result from the circulation of the planet's iron-rich liquid core. Particularly strong tidal effects caused by the planet's high orbital eccentricity would serve to keep the core in the liquid state necessary for this dynamo effect.[29]
+
+Mercury's magnetic field is strong enough to deflect the solar wind around the planet, creating a magnetosphere. The planet's magnetosphere, though small enough to fit within Earth,[81] is strong enough to trap solar wind plasma. This contributes to the space weathering of the planet's surface.[84] Observations taken by the Mariner 10 spacecraft detected this low energy plasma in the magnetosphere of the planet's nightside. Bursts of energetic particles in the planet's magnetotail indicate a dynamic quality to the planet's magnetosphere.[81]
+
+During its second flyby of the planet on October 6, 2008, MESSENGER discovered that Mercury's magnetic field can be extremely "leaky". The spacecraft encountered magnetic "tornadoes" – twisted bundles of magnetic fields connecting the planetary magnetic field to interplanetary space – that were up to 800 km wide or a third of the radius of the planet. These twisted magnetic flux tubes, technically known as flux transfer events, form open windows in the planet's magnetic shield through which the solar wind may enter and directly impact Mercury's surface via magnetic reconnection[87] This also occurs in Earth's magnetic field. The MESSENGER observations showed the reconnection rate is ten times higher at Mercury, but its proximity to the Sun only accounts for about a third of the reconnection rate observed by MESSENGER.[87]
+
+Mercury has the most eccentric orbit of all the planets; its eccentricity is 0.21 with its distance from the Sun ranging from 46,000,000 to 70,000,000 km (29,000,000 to 43,000,000 mi). It takes 87.969 Earth days to complete an orbit. The diagram illustrates the effects of the eccentricity, showing Mercury's orbit overlaid with a circular orbit having the same semi-major axis. Mercury's higher velocity when it is near perihelion is clear from the greater distance it covers in each 5-day interval. In the diagram the varying distance of Mercury to the Sun is represented by the size of the planet, which is inversely proportional to Mercury's distance from the Sun. This varying distance to the Sun leads to Mercury's surface being flexed by tidal bulges raised by the Sun that are about 17 times stronger than the Moon's on Earth.[88] Combined with a 3:2 spin–orbit resonance of the planet's rotation around its axis, it also results in complex variations of the surface temperature.[24]
+The resonance makes a single solar day on Mercury last exactly two Mercury years, or about 176 Earth days.[89]
+
+Mercury's orbit is inclined by 7 degrees to the plane of Earth's orbit (the ecliptic), as shown in the diagram on the right. As a result, transits of Mercury across the face of the Sun can only occur when the planet is crossing the plane of the ecliptic at the time it lies between Earth and the Sun, which is in May or November. This occurs about every seven years on average.[90]
+
+Mercury's axial tilt is almost zero,[91] with the best measured value as low as 0.027 degrees.[92] This is significantly smaller than that of Jupiter, which has the second smallest axial tilt of all planets at 3.1 degrees. This means that to an observer at Mercury's poles, the center of the Sun never rises more than 2.1 arcminutes above the horizon.[92]
+
+At certain points on Mercury's surface, an observer would be able to see the Sun peek up a little more than two-thirds of the way over the horizon, then reverse and set before rising again, all within the same Mercurian day.[93] This is because approximately four Earth days before perihelion, Mercury's angular orbital velocity equals its angular rotational velocity so that the Sun's apparent motion ceases; closer to perihelion, Mercury's angular orbital velocity then exceeds the angular rotational velocity. Thus, to a hypothetical observer on Mercury, the Sun appears to move in a retrograde direction. Four Earth days after perihelion, the Sun's normal apparent motion resumes.[24] A similar effect would have occurred if Mercury had been in synchronous rotation: the alternating gain and loss of rotation over revolution would have caused a libration of 23.65° in longitude.[94]
+
+For the same reason, there are two points on Mercury's equator, 180 degrees apart in longitude, at either of which, around perihelion in alternate Mercurian years (once a Mercurian day), the Sun passes overhead, then reverses its apparent motion and passes overhead again, then reverses a second time and passes overhead a third time, taking a total of about 16 Earth-days for this entire process. In the other alternate Mercurian years, the same thing happens at the other of these two points. The amplitude of the retrograde motion is small, so the overall effect is that, for two or three weeks, the Sun is almost stationary overhead, and is at its most brilliant because Mercury is at perihelion, its closest to the Sun. This prolonged exposure to the Sun at its brightest makes these two points the hottest places on Mercury. Maximum temperature occurs when the Sun is at an angle of about 25 degrees past noon due to diurnal temperature lag, at 0.4 Mercury days and 0.8 Mercury years past sunrise.[95] Conversely, there are two other points on the equator, 90 degrees of longitude apart from the first ones, where the Sun passes overhead only when the planet is at aphelion in alternate years, when the apparent motion of the Sun in Mercury's sky is relatively rapid. These points, which are the ones on the equator where the apparent retrograde motion of the Sun happens when it is crossing the horizon as described in the preceding paragraph, receive much less solar heat than the first ones described above.
+
+Mercury attains inferior conjunction (nearest approach to Earth) every 116 Earth days on average,[3] but this interval can range from 105 days to 129 days due to the planet's eccentric orbit. Mercury can come as near as 82.2 gigametres (0.549 astronomical units; 51.1 million miles) to Earth, and that is slowly declining: The next approach to within 82.1 Gm (51.0 million miles) is in 2679, and to within 82.0 Gm (51.0 million miles) in 4487, but it will not be closer to Earth than 80 Gm (50 million miles) until 28,622.[96] Its period of retrograde motion as seen from Earth can vary from 8 to 15 days on either side of inferior conjunction. This large range arises from the planet's high orbital eccentricity.[24] On average, Mercury is the closest planet to the Earth,[97] and it is the closest planet to each of the other planets in the Solar System.[98][99]
+
+The longitude convention for Mercury puts the zero of longitude at one of the two hottest points on the surface, as described above. However, when this area was first visited, by Mariner 10, this zero meridian was in darkness, so it was impossible to select a feature on the surface to define the exact position of the meridian. Therefore, a small crater further west was chosen, called Hun Kal, which provides the exact reference point for measuring longitude.[100][101] The center of Hun Kal defines the 20° west meridian. A 1970 International Astronomical Union resolution suggests that longitudes be measured positively in the westerly direction on Mercury.[102] The two hottest places on the equator are therefore at longitudes 0° W and 180° W, and the coolest points on the equator are at longitudes 90° W and 270° W. However, the MESSENGER project uses an east-positive convention.[103]
+
+For many years it was thought that Mercury was synchronously tidally locked with the Sun, rotating once for each orbit and always keeping the same face directed towards the Sun, in the same way that the same side of the Moon always faces Earth. Radar observations in 1965 proved that the planet has a 3:2 spin-orbit resonance, rotating three times for every two revolutions around the Sun. The eccentricity of Mercury's orbit makes this resonance stable—at perihelion, when the solar tide is strongest, the Sun is nearly still in Mercury's sky.[104]
+
+The rare 3:2 resonant tidal locking is stabilized by the variance of the tidal force along Mercury's eccentric orbit, acting on a permanent dipole component of Mercury's mass distribution.[105] In a circular orbit there is no such variance, so the only resonance stabilized in such an orbit is at 1:1 (e.g., Earth–Moon), when the tidal force, stretching a body along the "center-body" line, exerts a torque that aligns the body's axis of least inertia (the "longest" axis, and the axis of the aforementioned dipole) to point always at the center. However, with noticeable eccentricity, like that of Mercury's orbit, the tidal force has a maximum at perihelion and therefore stabilizes resonances, like 3:2, enforcing that the planet points its axis of least inertia roughly at the Sun when passing through perihelion.[105]
+
+The original reason astronomers thought it was synchronously locked was that, whenever Mercury was best placed for observation, it was always nearly at the same point in its 3:2 resonance, hence showing the same face. This is because, coincidentally, Mercury's rotation period is almost exactly half of its synodic period with respect to Earth. Due to Mercury's 3:2 spin-orbit resonance, a solar day (the length between two meridian transits of the Sun) lasts about 176 Earth days.[24] A sidereal day (the period of rotation) lasts about 58.7 Earth days.[24]
+
+Simulations indicate that the orbital eccentricity of Mercury varies chaotically from nearly zero (circular) to more than 0.45 over millions of years due to perturbations from the other planets.[24][106] 
+This was thought to explain Mercury's 3:2 spin-orbit resonance (rather than the more usual 1:1), because this state is more likely to arise during a period of high eccentricity.[107] 
+However, accurate modeling based on a realistic model of tidal response has demonstrated that Mercury was captured into the 3:2 spin-orbit state at a very early stage of its history, within 20 (more likely, 10) million years after its formation.[108]
+
+Numerical simulations show that a future secular orbital resonant perihelion interaction with Jupiter may cause the eccentricity of Mercury's orbit to increase to the point where there is a 1% chance that the planet may collide with Venus within the next five billion years.[109][110]
+
+In 1859, the French mathematician and astronomer Urbain Le Verrier reported that the slow precession of Mercury's orbit around the Sun could not be completely explained by Newtonian mechanics and perturbations by the known planets. He suggested, among possible explanations, that another planet (or perhaps instead a series of smaller 'corpuscules') might exist in an orbit even closer to the Sun than that of Mercury, to account for this perturbation.[111] (Other explanations considered included a slight oblateness of the Sun.) The success of the search for Neptune based on its perturbations of the orbit of Uranus led astronomers to place faith in this possible explanation, and the hypothetical planet was named Vulcan, but no such planet was ever found.[112]
+
+The perihelion precession of Mercury is 5,600 arcseconds (1.5556°) per century relative to Earth, or 574.10±0.65 arcseconds per century[113] relative to the inertial ICRF. Newtonian mechanics, taking into account all the effects from the other planets, predicts a precession of 5,557 arcseconds (1.5436°) per century.[113] In the early 20th century, Albert Einstein's general theory of relativity provided the explanation for the observed precession, by formalizing gravitation as being mediated by the curvature of spacetime. The effect is small: just 42.98 arcseconds per century for Mercury; it therefore requires a little over twelve million orbits for a full excess turn. Similar, but much smaller, effects exist for other Solar System bodies: 8.62 arcseconds per century for Venus, 3.84 for Earth, 1.35 for Mars, and 10.05 for 1566 Icarus.[114][115]
+
+Einstein's formula for the perihelion shift per revolution is 
+
+
+
+ϵ
+=
+24
+
+π
+
+3
+
+
+
+
+
+a
+
+2
+
+
+
+
+T
+
+2
+
+
+
+c
+
+2
+
+
+(
+1
+−
+
+e
+
+2
+
+
+)
+
+
+
+
+
+{\displaystyle \epsilon =24\pi ^{3}{\frac {a^{2}}{T^{2}c^{2}(1-e^{2})}}}
+
+, where 
+
+
+
+e
+
+
+{\displaystyle e}
+
+ is the orbital eccentricity, 
+
+
+
+a
+
+
+{\displaystyle a}
+
+ the semi-major axis, and 
+
+
+
+T
+
+
+{\displaystyle T}
+
+ the orbital period. Filling in the values gives a result of 0.1035 arcseconds per revolution or 0.4297 arcseconds per Earth year, i.e., 42.97 arcseconds per century. This is in close agreement with the accepted value of Mercury's perihelion advance of 42.98 arcseconds per century.[116]
+
+There may be scientific support, based on studies reported in March 2020, for considering that parts of the planet Mercury may have been habitable, and perhaps that life forms, albeit likely primitive microorganisms, may have existed on the planet.[117][118]
+
+Mercury's apparent magnitude is calculated to vary between −2.48 (brighter than Sirius) around superior conjunction and +7.25 (below the limit of naked-eye visibility) around inferior conjunction.[13] The mean apparent magnitude is 0.23 while the standard deviation of 1.78 is the largest of any planet. The mean apparent magnitude at superior conjunction is −1.89 while that at inferior conjunction is +5.93.[13] Observation of Mercury is complicated by its proximity to the Sun, as it is lost in the Sun's glare for much of the time. Mercury can be observed for only a brief period during either morning or evening twilight.[119]
+
+Mercury can, like several other planets and the brightest stars, be seen during a total solar eclipse.[120]
+
+Like the Moon and Venus, Mercury exhibits phases as seen from Earth. It is "new" at inferior conjunction and "full" at superior conjunction. The planet is rendered invisible from Earth on both of these occasions because of its being obscured by the Sun,[119] except its new phase during a transit.
+
+Mercury is technically brightest as seen from Earth when it is at a full phase. Although Mercury is farthest from Earth when it is full, the greater illuminated area that is visible and the opposition brightness surge more than compensates for the distance.[121] The opposite is true for Venus, which appears brightest when it is a crescent, because it is much closer to Earth than when gibbous.[121][122]
+
+Nonetheless, the brightest (full phase) appearance of Mercury is an essentially impossible time for practical observation, because of the extreme proximity of the Sun. Mercury is best observed at the first and last quarter, although they are phases of lesser brightness. The first and last quarter phases occur at greatest elongation east and west of the Sun, respectively. At both of these times Mercury's separation from the Sun ranges anywhere from 17.9° at perihelion to 27.8° at aphelion.[123][124] At greatest western elongation, Mercury rises at its earliest before sunrise, and at greatest eastern elongation, it sets at its latest after sunset.[125]
+
+Mercury can be easily seen from the tropics and subtropics more than from higher latitudes. Viewed from low latitudes and at the right times of year, the ecliptic intersects the horizon at a steep angle. Mercury is 10° above the horizon when the planet appears directly above the Sun (i.e. its orbit appears vertical) and is at maximum elongation from the Sun (28°) and also when the Sun is 18° below the horizon, so the sky is just completely dark.[d] This angle is the maximum altitude at which Mercury is visible in a completely dark sky.
+
+At middle latitudes, Mercury is more often and easily visible from the Southern Hemisphere than from the Northern. This is because Mercury's maximum western elongation occurs only during early autumn in the Southern Hemisphere, whereas its greatest eastern elongation happens only during late winter in the Southern Hemisphere.[125] In both of these cases, the angle at which the planet's orbit intersects the horizon is maximized, allowing it to rise several hours before sunrise in the former instance and not set until several hours after sundown in the latter from southern mid-latitudes, such as Argentina and South Africa.[125]
+
+An alternate method for viewing Mercury involves observing the planet during daylight hours when conditions are clear, ideally when it is at its greatest elongation. This allows the planet to be found easily, even when using telescopes with 8 cm (3.1 in) apertures. Care must be taken to ensure the instrument isn't pointed directly towards the Sun because of the risk for eye damage. This method bypasses the limitation of twilight observing when the ecliptic is located at a low elevation (e.g. on autumn evenings).
+
+Ground-based telescope observations of Mercury reveal only an illuminated partial disk with limited detail. The first of two spacecraft to visit the planet was Mariner 10, which mapped about 45% of its surface from 1974 to 1975. The second is the MESSENGER spacecraft, which after three Mercury flybys between 2008 and 2009, attained orbit around Mercury on March 17, 2011,[126] to study and map the rest of the planet.[127]
+
+The Hubble Space Telescope cannot observe Mercury at all, due to safety procedures that prevent its pointing too close to the Sun.[128]
+
+Because the shift of 0.15 revolutions in a year makes up a seven-year cycle (0.15 × 7 ≈ 1.0), in the seventh year Mercury follows almost exactly (earlier by 7 days) the sequence of phenomena it showed seven years before.[123]
+
+The earliest known recorded observations of Mercury are from the Mul.Apin tablets. These observations were most likely made by an Assyrian astronomer around the 14th century BC.[129] The cuneiform name used to designate Mercury on the Mul.Apin tablets is transcribed as Udu.Idim.Gu\u4.Ud ("the jumping planet").[e][130] Babylonian records of Mercury date back to the 1st millennium BC. The Babylonians called the planet Nabu after the messenger to the gods in their mythology.[131]
+
+The ancients knew Mercury by different names depending on whether it was an evening star or a morning star. By about 350 BC, the ancient Greeks had realized the two stars were one.[132] They knew the planet as Στίλβων Stilbōn, meaning "twinkling", and Ἑρμής Hermēs, for its fleeting motion,[133] a name that is retained in modern Greek (Ερμής Ermis).[134] The Romans named the planet after the swift-footed Roman messenger god, Mercury (Latin Mercurius), which they equated with the Greek Hermes, because it moves across the sky faster than any other planet.[132][135] The astronomical symbol for Mercury is a stylized version of Hermes' caduceus.[136]
+
+The Greco-Egyptian[137] astronomer Ptolemy wrote about the possibility of planetary transits across the face of the Sun in his work Planetary Hypotheses. He suggested that no transits had been observed either because planets such as Mercury were too small to see, or because the transits were too infrequent.[138]
+
+In ancient China, Mercury was known as "the Hour Star" (Chen-xing 辰星). It was associated with the direction north and the phase of water in the Five Phases system of metaphysics.[139] Modern Chinese, Korean, Japanese and Vietnamese cultures refer to the planet literally as the "water star" (水星), based on the Five elements.[140][141][142] Hindu mythology used the name Budha for Mercury, and this god was thought to preside over Wednesday.[143] The god Odin (or Woden) of Germanic paganism was associated with the planet Mercury and Wednesday.[144] The Maya may have represented Mercury as an owl (or possibly four owls; two for the morning aspect and two for the evening) that served as a messenger to the underworld.[145]
+
+In medieval Islamic astronomy, the Andalusian astronomer Abū Ishāq Ibrāhīm al-Zarqālī in the 11th century described the deferent of Mercury's geocentric orbit as being oval, like an egg or a pignon, although this insight did not influence his astronomical theory or his astronomical calculations.[146][147] In the 12th century, Ibn Bajjah observed "two planets as black spots on the face of the Sun", which was later suggested as the transit of Mercury and/or Venus by the Maragha astronomer Qotb al-Din Shirazi in the 13th century.[148] (Note that most such medieval reports of transits were later taken as observations of sunspots.[149])
+
+In India, the Kerala school astronomer Nilakantha Somayaji in the 15th century developed a partially heliocentric planetary model in which Mercury orbits the Sun, which in turn orbits Earth, similar to the Tychonic system later proposed by Tycho Brahe in the late 16th century.[150]
+
+The first telescopic observations of Mercury were made by Galileo in the early 17th century. Although he observed phases when he looked at Venus, his telescope was not powerful enough to see the phases of Mercury. In 1631, Pierre Gassendi made the first telescopic observations of the transit of a planet across the Sun when he saw a transit of Mercury predicted by Johannes Kepler. In 1639, Giovanni Zupi used a telescope to discover that the planet had orbital phases similar to Venus and the Moon. The observation demonstrated conclusively that Mercury orbited around the Sun.[24]
+
+A rare event in astronomy is the passage of one planet in front of another (occultation), as seen from Earth. Mercury and Venus occult each other every few centuries, and the event of May 28, 1737 is the only one historically observed, having been seen by John Bevis at the Royal Greenwich Observatory.[151] The next occultation of Mercury by Venus will be on December 3, 2133.[152]
+
+The difficulties inherent in observing Mercury mean that it has been far less studied than the other planets. In 1800, Johann Schröter made observations of surface features, claiming to have observed 20-kilometre-high (12 mi) mountains. Friedrich Bessel used Schröter's drawings to erroneously estimate the rotation period as 24 hours and an axial tilt of 70°.[153] In the 1880s, Giovanni Schiaparelli mapped the planet more accurately, and suggested that Mercury's rotational period was 88 days, the same as its orbital period due to tidal locking.[154] This phenomenon is known as synchronous rotation. The effort to map the surface of Mercury was continued by Eugenios Antoniadi, who published a book in 1934 that included both maps and his own observations.[81] Many of the planet's surface features, particularly the albedo features, take their names from Antoniadi's map.[155]
+
+In June 1962, Soviet scientists at the Institute of Radio-engineering and Electronics of the USSR Academy of Sciences, led by Vladimir Kotelnikov, became the first to bounce a radar signal off Mercury and receive it, starting radar observations of the planet.[156][157][158] Three years later, radar observations by Americans Gordon H. Pettengill and Rolf B. Dyce, using the 300-meter Arecibo Observatory radio telescope in Puerto Rico, showed conclusively that the planet's rotational period was about 59 days.[159][160] The theory that Mercury's rotation was synchronous had become widely held, and it was a surprise to astronomers when these radio observations were announced. If Mercury were tidally locked, its dark face would be extremely cold, but measurements of radio emission revealed that it was much hotter than expected. Astronomers were reluctant to drop the synchronous rotation theory and proposed alternative mechanisms such as powerful heat-distributing winds to explain the observations.[161]
+
+Italian astronomer Giuseppe Colombo noted that the rotation value was about two-thirds of Mercury's orbital period, and proposed that the planet's orbital and rotational periods were locked into a 3:2 rather than a 1:1 resonance.[162] Data from Mariner 10 subsequently confirmed this view.[163] This means that Schiaparelli's and Antoniadi's maps were not "wrong". Instead, the astronomers saw the same features during every second orbit and recorded them, but disregarded those seen in the meantime, when Mercury's other face was toward the Sun, because the orbital geometry meant that these observations were made under poor viewing conditions.[153]
+
+Ground-based optical observations did not shed much further light on Mercury, but radio astronomers using interferometry at microwave wavelengths, a technique that enables removal of the solar radiation, were able to discern physical and chemical characteristics of the subsurface layers to a depth of several meters.[164][165] Not until the first space probe flew past Mercury did many of its most fundamental morphological properties become known. Moreover, recent technological advances have led to improved ground-based observations. In 2000, high-resolution lucky imaging observations were conducted by the Mount Wilson Observatory 1.5 meter Hale telescope. They provided the first views that resolved surface features on the parts of Mercury that were not imaged in the Mariner 10 mission.[166] Most of the planet has been mapped by the Arecibo radar telescope, with 5 km (3.1 mi) resolution, including polar deposits in shadowed craters of what may be water ice.[167]
+
+Reaching Mercury from Earth poses significant technical challenges, because it orbits so much closer to the Sun than Earth. A Mercury-bound spacecraft launched from Earth must travel over 91 million kilometres (57 million miles) into the Sun's gravitational potential well. Mercury has an orbital speed of 48 km/s (30 mi/s), whereas Earth's orbital speed is 30 km/s (19 mi/s). Therefore, the spacecraft must make a large change in velocity (delta-v) to enter a Hohmann transfer orbit that passes near Mercury, as compared to the delta-v required for other planetary missions.[169]
+
+The potential energy liberated by moving down the Sun's potential well becomes kinetic energy; requiring another large delta-v change to do anything other than rapidly pass by Mercury. To land safely or enter a stable orbit the spacecraft would rely entirely on rocket motors. Aerobraking is ruled out because Mercury has a negligible atmosphere. A trip to Mercury requires more rocket fuel than that required to escape the Solar System completely. As a result, only two space probes have visited it so far.[170] A proposed alternative approach would use a solar sail to attain a Mercury-synchronous orbit around the Sun.[171]
+
+The first spacecraft to visit Mercury was NASA's Mariner 10 (1974–1975).[132] The spacecraft used the gravity of Venus to adjust its orbital velocity so that it could approach Mercury, making it both the first spacecraft to use this gravitational "slingshot" effect and the first NASA mission to visit multiple planets.[169] Mariner 10 provided the first close-up images of Mercury's surface, which immediately showed its heavily cratered nature, and revealed many other types of geological features, such as the giant scarps that were later ascribed to the effect of the planet shrinking slightly as its iron core cools.[172] Unfortunately, the same face of the planet was lit at each of Mariner 10's close approaches. This made close observation of both sides of the planet impossible,[173] and resulted in the mapping of less than 45% of the planet's surface.[174]
+
+The spacecraft made three close approaches to Mercury, the closest of which took it to within 327 km (203 mi) of the surface.[175] At the first close approach, instruments detected a magnetic field, to the great surprise of planetary geologists—Mercury's rotation was expected to be much too slow to generate a significant dynamo effect. The second close approach was primarily used for imaging, but at the third approach, extensive magnetic data were obtained. The data revealed that the planet's magnetic field is much like Earth's, which deflects the solar wind around the planet. For many years after the Mariner 10 encounters, the origin of Mercury's magnetic field remained the subject of several competing theories.[176][177]
+
+On March 24, 1975, just eight days after its final close approach, Mariner 10 ran out of fuel. Because its orbit could no longer be accurately controlled, mission controllers instructed the probe to shut down.[178] Mariner 10 is thought to be still orbiting the Sun, passing close to Mercury every few months.[179]
+
+A second NASA mission to Mercury, named MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging), was launched on August 3, 2004. It made a fly-by of Earth in August 2005, and of Venus in October 2006 and June 2007 to place it onto the correct trajectory to reach an orbit around Mercury.[180] A first fly-by of Mercury occurred on January 14, 2008, a second on October 6, 2008,[181] and a third on September 29, 2009.[182] Most of the hemisphere not imaged by Mariner 10 was mapped during these fly-bys. The probe successfully entered an elliptical orbit around the planet on March 18, 2011. The first orbital image of Mercury was obtained on March 29, 2011. The probe finished a one-year mapping mission,[181] and then entered a one-year extended mission into 2013. In addition to continued observations and mapping of Mercury, MESSENGER observed the 2012 solar maximum.[183]
+
+The mission was designed to clear up six key issues: Mercury's high density, its geological history, the nature of its magnetic field, the structure of its core, whether it has ice at its poles, and where its tenuous atmosphere comes from. To this end, the probe carried imaging devices that gathered much-higher-resolution images of much more of Mercury than Mariner 10, assorted spectrometers to determine abundances of elements in the crust, and magnetometers and devices to measure velocities of charged particles. Measurements of changes in the probe's orbital velocity were expected to be used to infer details of the planet's interior structure.[184] MESSENGER's final maneuver was on April 24, 2015, and it crashed into Mercury's surface on April 30, 2015.[185][186][187] The spacecraft's impact with Mercury occurred near 3:26 PM EDT on April 30, 2015, leaving a crater estimated to be 16 m (52 ft) in diameter.[188]
+
+The European Space Agency and the Japanese Space Agency developed and launched a joint mission called BepiColombo, which will orbit Mercury with two probes: one to map the planet and the other to study its magnetosphere.[189] Launched on October 20, 2018, BepiColombo is expected to reach Mercury in 2025.[190] It will release a magnetometer probe into an elliptical orbit, then chemical rockets will fire to deposit the mapper probe into a circular orbit. Both probes will operate for one terrestrial year.[189] The mapper probe carries an array of spectrometers similar to those on MESSENGER, and will study the planet at many different wavelengths including infrared, ultraviolet, X-ray and gamma ray.[191]
+
+Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Observable universe → UniverseEach arrow (→) may be read as "within" or "part of".
+

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+Mercury is the smallest and innermost planet in the Solar System. Its orbit around the Sun takes 87.97 days, the shortest of all the planets in the Solar System. It is named after the Roman deity Mercury, the messenger of the gods.
+
+Like Venus, Mercury orbits the Sun within Earth's orbit as an inferior planet, and its apparent distance from the Sun as viewed from Earth never exceeds 28°. This proximity to the Sun means the planet can only be seen near the western horizon after sunset or eastern horizon before sunrise, usually in twilight. At this time, it may appear as a bright star-like object, but is often far more difficult to observe than Venus. The planet telescopically displays the complete range of phases, similar to Venus and the Moon, as it moves in its inner orbit relative to Earth, which recurs over its synodic period of approximately 116 days.
+
+Mercury rotates in a way that is unique in the Solar System. It is tidally locked with the Sun in a 3:2 spin–orbit resonance,[16] meaning that relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around the Sun.[a][17] As seen from the Sun, in a frame of reference that rotates with the orbital motion, it appears to rotate only once every two Mercurian years. An observer on Mercury would therefore see only one day every two Mercurian years.
+
+Mercury's axis has the smallest tilt of any of the Solar System's planets (about ​1⁄30 degree). Its orbital eccentricity is the largest of all known planets in the Solar System;[b] at perihelion, Mercury's distance from the Sun is only about two-thirds (or 66%) of its distance at aphelion. Mercury's surface appears heavily cratered and is similar in appearance to the Moon's, indicating that it has been geologically inactive for billions of years. Having almost no atmosphere to retain heat, it has surface temperatures that vary diurnally more than on any other planet in the Solar System, ranging from 100 K (−173 °C; −280 °F) at night to 700 K (427 °C; 800 °F) during the day across the equatorial regions.[18] The polar regions are constantly below 180 K (−93 °C; −136 °F). The planet has no known natural satellites.
+
+Two spacecraft have visited Mercury: Mariner 10 flew by in 1974 and 1975; and MESSENGER, launched in 2004, orbited Mercury over 4,000 times in four years before exhausting its fuel and crashing into the planet's surface on April 30, 2015.[19][20][21] The BepiColombo spacecraft is planned to arrive at Mercury in 2025.
+
+Mercury appears to have a solid silicate crust and mantle overlying a solid, iron sulfide outer core layer, a deeper liquid core layer, and a solid inner core.[22][23]
+
+Mercury is one of four terrestrial planets in the Solar System, and is a rocky body like Earth. It is the smallest planet in the Solar System, with an equatorial radius of 2,439.7 kilometres (1,516.0 mi).[3] Mercury is also smaller—albeit more massive—than the largest natural satellites in the Solar System, Ganymede and Titan. Mercury consists of approximately 70% metallic and 30% silicate material.[24] Mercury's density is the second highest in the Solar System at 5.427 g/cm3, only slightly less than Earth's density of 5.515 g/cm3.[3] If the effect of gravitational compression were to be factored out from both planets, the materials of which Mercury is made would be denser than those of Earth, with an uncompressed density of 5.3 g/cm3 versus Earth's 4.4 g/cm3.[25]
+
+Mercury's density can be used to infer details of its inner structure. Although Earth's high density results appreciably from gravitational compression, particularly at the core, Mercury is much smaller and its inner regions are not as compressed. Therefore, for it to have such a high density, its core must be large and rich in iron.[26]
+
+Geologists estimate that Mercury's core occupies about 55% of its volume; for Earth this proportion is 17%. Research published in 2007 suggests that Mercury has a molten core.[27][28] Surrounding the core is a 500–700 km (310–430 mi) mantle consisting of silicates.[29][30] Based on data from the Mariner 10 mission and Earth-based observation, Mercury's crust is estimated to be 35 km (22 mi) thick.[31] One distinctive feature of Mercury's surface is the presence of numerous narrow ridges, extending up to several hundred kilometers in length. It is thought that these were formed as Mercury's core and mantle cooled and contracted at a time when the crust had already solidified.[32]
+
+Mercury's core has a higher iron content than that of any other major planet in the Solar System, and several theories have been proposed to explain this. The most widely accepted theory is that Mercury originally had a metal–silicate ratio similar to common chondrite meteorites, thought to be typical of the Solar System's rocky matter, and a mass approximately 2.25 times its current mass.[33] Early in the Solar System's history, Mercury may have been struck by a planetesimal of approximately 1/6 that mass and several thousand kilometers across.[33] The impact would have stripped away much of the original crust and mantle, leaving the core behind as a relatively major component.[33] A similar process, known as the giant impact hypothesis, has been proposed to explain the formation of the Moon.[33]
+
+Alternatively, Mercury may have formed from the solar nebula before the Sun's energy output had stabilized. It would initially have had twice its present mass, but as the protosun contracted, temperatures near Mercury could have been between 2,500 and 3,500 K and possibly even as high as 10,000 K.[34] Much of Mercury's surface rock could have been vaporized at such temperatures, forming an atmosphere of "rock vapor" that could have been carried away by the solar wind.[34]
+
+A third hypothesis proposes that the solar nebula caused drag on the particles from which Mercury was accreting, which meant that lighter particles were lost from the accreting material and not gathered by Mercury.[35] Each hypothesis predicts a different surface composition, and there are two space missions set to make observations. MESSENGER, which ended in 2015, found higher-than-expected potassium and sulfur levels on the surface, suggesting that the giant impact hypothesis and vaporization of the crust and mantle did not occur because potassium and sulfur would have been driven off by the extreme heat of these events.[36] BepiColombo, which will arrive at Mercury in 2025, will make observations to test these hypotheses.[37] The findings so far would seem to favor the third hypothesis; however, further analysis of the data is needed.[38]
+
+Mercury's surface is similar in appearance to that of the Moon, showing extensive mare-like plains and heavy cratering, indicating that it has been geologically inactive for billions of years. Because knowledge of Mercury's geology had been based only on the 1975 Mariner 10 flyby and terrestrial observations, it is the least understood of the terrestrial planets.[28] As data from MESSENGER orbiter are processed, this knowledge will increase. For example, an unusual crater with radiating troughs has been discovered that scientists called "the spider".[39] It was later named Apollodorus.[40]
+
+Albedo features are areas of markedly different reflectivity, as seen by telescopic observation. Mercury has dorsa (also called "wrinkle-ridges"), Moon-like highlands, montes (mountains), planitiae (plains), rupes (escarpments), and valles (valleys).[41][42]
+
+Names for features on Mercury come from a variety of sources. Names coming from people are limited to the deceased. Craters are named for artists, musicians, painters, and authors who have made outstanding or fundamental contributions to their field. Ridges, or dorsa, are named for scientists who have contributed to the study of Mercury. Depressions or fossae are named for works of architecture. Montes are named for the word "hot" in a variety of languages. Plains or planitiae are named for Mercury in various languages. Escarpments or rupēs are named for ships of scientific expeditions. Valleys or valles are named for abandoned cities, towns, or settlements of antiquity.[43]
+
+Mercury was heavily bombarded by comets and asteroids during and shortly following its formation 4.6 billion years ago, as well as during a possibly separate subsequent episode called the Late Heavy Bombardment that ended 3.8 billion years ago.[44] During this period of intense crater formation, Mercury received impacts over its entire surface,[42] facilitated by the lack of any atmosphere to slow impactors down.[45] During this time Mercury was volcanically active; basins such as the Caloris Basin were filled by magma, producing smooth plains similar to the maria found on the Moon.[46][47]
+
+Data from the October 2008 flyby of MESSENGER gave researchers a greater appreciation for the jumbled nature of Mercury's surface. Mercury's surface is more heterogeneous than either Mars's or the Moon's, both of which contain significant stretches of similar geology, such as maria and plateaus.[48]
+
+Craters on Mercury range in diameter from small bowl-shaped cavities to multi-ringed impact basins hundreds of kilometers across. They appear in all states of degradation, from relatively fresh rayed craters to highly degraded crater remnants. Mercurian craters differ subtly from lunar craters in that the area blanketed by their ejecta is much smaller, a consequence of Mercury's stronger surface gravity.[49] According to IAU rules, each new crater must be named after an artist that was famous for more than fifty years, and dead for more than three years, before the date the crater is named.[50]
+
+The largest known crater is Caloris Basin, with a diameter of 1,550 km.[51] The impact that created the Caloris Basin was so powerful that it caused lava eruptions and left a concentric ring over 2 km tall surrounding the impact crater. At the antipode of the Caloris Basin is a large region of unusual, hilly terrain known as the "Weird Terrain". One hypothesis for its origin is that shock waves generated during the Caloris impact traveled around Mercury, converging at the basin's antipode (180 degrees away). The resulting high stresses fractured the surface.[52] Alternatively, it has been suggested that this terrain formed as a result of the convergence of ejecta at this basin's antipode.[53]
+
+Overall, about 15 impact basins have been identified on the imaged part of Mercury. A notable basin is the 400 km wide, multi-ring Tolstoj Basin that has an ejecta blanket extending up to 500 km from its rim and a floor that has been filled by smooth plains materials. Beethoven Basin has a similar-sized ejecta blanket and a 625 km diameter rim.[49] Like the Moon, the surface of Mercury has likely incurred the effects of space weathering processes, including Solar wind and micrometeorite impacts.[54]
+
+There are two geologically distinct plains regions on Mercury.[49][55] Gently rolling, hilly plains in the regions between craters are Mercury's oldest visible surfaces,[49] predating the heavily cratered terrain. These inter-crater plains appear to have obliterated many earlier craters, and show a general paucity of smaller craters below about 30 km in diameter.[55]
+
+Smooth plains are widespread flat areas that fill depressions of various sizes and bear a strong resemblance to the lunar maria. Notably, they fill a wide ring surrounding the Caloris Basin. Unlike lunar maria, the smooth plains of Mercury have the same albedo as the older inter-crater plains. Despite a lack of unequivocally volcanic characteristics, the localisation and rounded, lobate shape of these plains strongly support volcanic origins.[49] All the smooth plains of Mercury formed significantly later than the Caloris basin, as evidenced by appreciably smaller crater densities than on the Caloris ejecta blanket.[49] The floor of the Caloris Basin is filled by a geologically distinct flat plain, broken up by ridges and fractures in a roughly polygonal pattern. It is not clear whether they are volcanic lavas induced by the impact, or a large sheet of impact melt.[49]
+
+One unusual feature of Mercury's surface is the numerous compression folds, or rupes, that crisscross the plains. As Mercury's interior cooled, it contracted and its surface began to deform, creating wrinkle ridges and lobate scarps associated with thrust faults. The scarps can reach lengths of 1000 km and heights of 3 km.[56] These compressional features can be seen on top of other features, such as craters and smooth plains, indicating they are more recent.[57] Mapping of the features has suggested a total shrinkage of Mercury's radius in the range of ~1 to 7 km.[58] Small-scale thrust fault scarps have been found, tens of meters in height and with lengths in the range of a few km, that appear to be less than 50 million years old, indicating that compression of the interior and consequent surface geological activity continue to the present.[56][58]
+
+The Lunar Reconnaissance Orbiter discovered that similar small thrust faults exist on the Moon.
+
+Images obtained by MESSENGER have revealed evidence for pyroclastic flows on Mercury from low-profile shield volcanoes.[59][60][61] MESSENGER data has helped identify 51 pyroclastic deposits on the surface,[62] where 90% of them are found within impact craters.[62] A study of the degradation state of the impact craters that host pyroclastic deposits suggests that pyroclastic activity occurred on Mercury over a prolonged interval.[62]
+
+A "rimless depression" inside the southwest rim of the Caloris Basin consists of at least nine overlapping volcanic vents, each individually up to 8 km in diameter. It is thus a "compound volcano".[63] The vent floors are at a least 1 km below their brinks and they bear a closer resemblance to volcanic craters sculpted by explosive eruptions or modified by collapse into void spaces created by magma withdrawal back down into a conduit.[63] Scientists could not quantify the age of the volcanic complex system, but reported that it could be of the order of a billion years.[63]
+
+The surface temperature of Mercury ranges from 100 to 700 K (−173 to 427 °C; −280 to 800 °F)[18] at the most extreme places: 0°N, 0°W, or 180°W. It never rises above 180 K at the poles,[12]
+due to the absence of an atmosphere and a steep temperature gradient between the equator and the poles. The subsolar point reaches about 700 K during perihelion (0°W or 180°W), but only 550 K at aphelion (90° or 270°W).[65]
+On the dark side of the planet, temperatures average 110 K.[12][66]
+The intensity of sunlight on Mercury's surface ranges between 4.59 and 10.61 times the solar constant (1,370 W·m−2).[67]
+
+Although the daylight temperature at the surface of Mercury is generally extremely high, observations strongly suggest that ice (frozen water) exists on Mercury. The floors of deep craters at the poles are never exposed to direct sunlight, and temperatures there remain below 102 K; far lower than the global average.[68] Water ice strongly reflects radar, and observations by the 70-meter Goldstone Solar System Radar and the VLA in the early 1990s revealed that there are patches of high radar reflection near the poles.[69] Although ice was not the only possible cause of these reflective regions, astronomers think it was the most likely.[70]
+
+The icy regions are estimated to contain about 1014–1015 kg of ice,[71] and may be covered by a layer of regolith that inhibits sublimation.[72] By comparison, the Antarctic ice sheet on Earth has a mass of about 4×1018 kg, and Mars's south polar cap contains about 1016 kg of water.[71] The origin of the ice on Mercury is not yet known, but the two most likely sources are from outgassing of water from the planet's interior or deposition by impacts of comets.[71]
+
+Mercury is too small and hot for its gravity to retain any significant atmosphere over long periods of time; it does have a tenuous surface-bounded exosphere[73] containing hydrogen, helium, oxygen, sodium, calcium, potassium and others at a surface pressure of less than approximately 0.5 nPa (0.005 picobars).[14] This exosphere is not stable—atoms are continuously lost and replenished from a variety of sources. Hydrogen atoms and helium atoms probably come from the solar wind, diffusing into Mercury's magnetosphere before later escaping back into space. Radioactive decay of elements within Mercury's crust is another source of helium, as well as sodium and potassium. MESSENGER found high proportions of calcium, helium, hydroxide, magnesium, oxygen, potassium, silicon and sodium. Water vapor is present, released by a combination of processes such as: comets striking its surface, sputtering creating water out of hydrogen from the solar wind and oxygen from rock, and sublimation from reservoirs of water ice in the permanently shadowed polar craters. The detection of high amounts of water-related ions like O+, OH−, and H3O+ was a surprise.[74][75] Because of the quantities of these ions that were detected in Mercury's space environment, scientists surmise that these molecules were blasted from the surface or exosphere by the solar wind.[76][77]
+
+Sodium, potassium and calcium were discovered in the atmosphere during the 1980–1990s, and are thought to result primarily from the vaporization of surface rock struck by micrometeorite impacts[78] including presently from Comet Encke.[79] In 2008, magnesium was discovered by MESSENGER.[80] Studies indicate that, at times, sodium emissions are localized at points that correspond to the planet's magnetic poles. This would indicate an interaction between the magnetosphere and the planet's surface.[81]
+
+On November 29, 2012, NASA confirmed that images from MESSENGER had detected that craters at the north pole contained water ice. MESSENGER's principal investigator Sean Solomon is quoted in The New York Times estimating the volume of the ice to be large enough to "encase Washington, D.C., in a frozen block two and a half miles deep".[64][c]
+
+Despite its small size and slow 59-day-long rotation, Mercury has a significant, and apparently global, magnetic field. According to measurements taken by Mariner 10, it is about 1.1% the strength of Earth's. The magnetic-field strength at Mercury's equator is about 300 nT.[82][83] Like that of Earth, Mercury's magnetic field is dipolar.[81] Unlike Earth's, Mercury's poles are nearly aligned with the planet's spin axis.[84] Measurements from both the Mariner 10 and MESSENGER space probes have indicated that the strength and shape of the magnetic field are stable.[84]
+
+It is likely that this magnetic field is generated by a dynamo effect, in a manner similar to the magnetic field of Earth.[85][86] This dynamo effect would result from the circulation of the planet's iron-rich liquid core. Particularly strong tidal effects caused by the planet's high orbital eccentricity would serve to keep the core in the liquid state necessary for this dynamo effect.[29]
+
+Mercury's magnetic field is strong enough to deflect the solar wind around the planet, creating a magnetosphere. The planet's magnetosphere, though small enough to fit within Earth,[81] is strong enough to trap solar wind plasma. This contributes to the space weathering of the planet's surface.[84] Observations taken by the Mariner 10 spacecraft detected this low energy plasma in the magnetosphere of the planet's nightside. Bursts of energetic particles in the planet's magnetotail indicate a dynamic quality to the planet's magnetosphere.[81]
+
+During its second flyby of the planet on October 6, 2008, MESSENGER discovered that Mercury's magnetic field can be extremely "leaky". The spacecraft encountered magnetic "tornadoes" – twisted bundles of magnetic fields connecting the planetary magnetic field to interplanetary space – that were up to 800 km wide or a third of the radius of the planet. These twisted magnetic flux tubes, technically known as flux transfer events, form open windows in the planet's magnetic shield through which the solar wind may enter and directly impact Mercury's surface via magnetic reconnection[87] This also occurs in Earth's magnetic field. The MESSENGER observations showed the reconnection rate is ten times higher at Mercury, but its proximity to the Sun only accounts for about a third of the reconnection rate observed by MESSENGER.[87]
+
+Mercury has the most eccentric orbit of all the planets; its eccentricity is 0.21 with its distance from the Sun ranging from 46,000,000 to 70,000,000 km (29,000,000 to 43,000,000 mi). It takes 87.969 Earth days to complete an orbit. The diagram illustrates the effects of the eccentricity, showing Mercury's orbit overlaid with a circular orbit having the same semi-major axis. Mercury's higher velocity when it is near perihelion is clear from the greater distance it covers in each 5-day interval. In the diagram the varying distance of Mercury to the Sun is represented by the size of the planet, which is inversely proportional to Mercury's distance from the Sun. This varying distance to the Sun leads to Mercury's surface being flexed by tidal bulges raised by the Sun that are about 17 times stronger than the Moon's on Earth.[88] Combined with a 3:2 spin–orbit resonance of the planet's rotation around its axis, it also results in complex variations of the surface temperature.[24]
+The resonance makes a single solar day on Mercury last exactly two Mercury years, or about 176 Earth days.[89]
+
+Mercury's orbit is inclined by 7 degrees to the plane of Earth's orbit (the ecliptic), as shown in the diagram on the right. As a result, transits of Mercury across the face of the Sun can only occur when the planet is crossing the plane of the ecliptic at the time it lies between Earth and the Sun, which is in May or November. This occurs about every seven years on average.[90]
+
+Mercury's axial tilt is almost zero,[91] with the best measured value as low as 0.027 degrees.[92] This is significantly smaller than that of Jupiter, which has the second smallest axial tilt of all planets at 3.1 degrees. This means that to an observer at Mercury's poles, the center of the Sun never rises more than 2.1 arcminutes above the horizon.[92]
+
+At certain points on Mercury's surface, an observer would be able to see the Sun peek up a little more than two-thirds of the way over the horizon, then reverse and set before rising again, all within the same Mercurian day.[93] This is because approximately four Earth days before perihelion, Mercury's angular orbital velocity equals its angular rotational velocity so that the Sun's apparent motion ceases; closer to perihelion, Mercury's angular orbital velocity then exceeds the angular rotational velocity. Thus, to a hypothetical observer on Mercury, the Sun appears to move in a retrograde direction. Four Earth days after perihelion, the Sun's normal apparent motion resumes.[24] A similar effect would have occurred if Mercury had been in synchronous rotation: the alternating gain and loss of rotation over revolution would have caused a libration of 23.65° in longitude.[94]
+
+For the same reason, there are two points on Mercury's equator, 180 degrees apart in longitude, at either of which, around perihelion in alternate Mercurian years (once a Mercurian day), the Sun passes overhead, then reverses its apparent motion and passes overhead again, then reverses a second time and passes overhead a third time, taking a total of about 16 Earth-days for this entire process. In the other alternate Mercurian years, the same thing happens at the other of these two points. The amplitude of the retrograde motion is small, so the overall effect is that, for two or three weeks, the Sun is almost stationary overhead, and is at its most brilliant because Mercury is at perihelion, its closest to the Sun. This prolonged exposure to the Sun at its brightest makes these two points the hottest places on Mercury. Maximum temperature occurs when the Sun is at an angle of about 25 degrees past noon due to diurnal temperature lag, at 0.4 Mercury days and 0.8 Mercury years past sunrise.[95] Conversely, there are two other points on the equator, 90 degrees of longitude apart from the first ones, where the Sun passes overhead only when the planet is at aphelion in alternate years, when the apparent motion of the Sun in Mercury's sky is relatively rapid. These points, which are the ones on the equator where the apparent retrograde motion of the Sun happens when it is crossing the horizon as described in the preceding paragraph, receive much less solar heat than the first ones described above.
+
+Mercury attains inferior conjunction (nearest approach to Earth) every 116 Earth days on average,[3] but this interval can range from 105 days to 129 days due to the planet's eccentric orbit. Mercury can come as near as 82.2 gigametres (0.549 astronomical units; 51.1 million miles) to Earth, and that is slowly declining: The next approach to within 82.1 Gm (51.0 million miles) is in 2679, and to within 82.0 Gm (51.0 million miles) in 4487, but it will not be closer to Earth than 80 Gm (50 million miles) until 28,622.[96] Its period of retrograde motion as seen from Earth can vary from 8 to 15 days on either side of inferior conjunction. This large range arises from the planet's high orbital eccentricity.[24] On average, Mercury is the closest planet to the Earth,[97] and it is the closest planet to each of the other planets in the Solar System.[98][99]
+
+The longitude convention for Mercury puts the zero of longitude at one of the two hottest points on the surface, as described above. However, when this area was first visited, by Mariner 10, this zero meridian was in darkness, so it was impossible to select a feature on the surface to define the exact position of the meridian. Therefore, a small crater further west was chosen, called Hun Kal, which provides the exact reference point for measuring longitude.[100][101] The center of Hun Kal defines the 20° west meridian. A 1970 International Astronomical Union resolution suggests that longitudes be measured positively in the westerly direction on Mercury.[102] The two hottest places on the equator are therefore at longitudes 0° W and 180° W, and the coolest points on the equator are at longitudes 90° W and 270° W. However, the MESSENGER project uses an east-positive convention.[103]
+
+For many years it was thought that Mercury was synchronously tidally locked with the Sun, rotating once for each orbit and always keeping the same face directed towards the Sun, in the same way that the same side of the Moon always faces Earth. Radar observations in 1965 proved that the planet has a 3:2 spin-orbit resonance, rotating three times for every two revolutions around the Sun. The eccentricity of Mercury's orbit makes this resonance stable—at perihelion, when the solar tide is strongest, the Sun is nearly still in Mercury's sky.[104]
+
+The rare 3:2 resonant tidal locking is stabilized by the variance of the tidal force along Mercury's eccentric orbit, acting on a permanent dipole component of Mercury's mass distribution.[105] In a circular orbit there is no such variance, so the only resonance stabilized in such an orbit is at 1:1 (e.g., Earth–Moon), when the tidal force, stretching a body along the "center-body" line, exerts a torque that aligns the body's axis of least inertia (the "longest" axis, and the axis of the aforementioned dipole) to point always at the center. However, with noticeable eccentricity, like that of Mercury's orbit, the tidal force has a maximum at perihelion and therefore stabilizes resonances, like 3:2, enforcing that the planet points its axis of least inertia roughly at the Sun when passing through perihelion.[105]
+
+The original reason astronomers thought it was synchronously locked was that, whenever Mercury was best placed for observation, it was always nearly at the same point in its 3:2 resonance, hence showing the same face. This is because, coincidentally, Mercury's rotation period is almost exactly half of its synodic period with respect to Earth. Due to Mercury's 3:2 spin-orbit resonance, a solar day (the length between two meridian transits of the Sun) lasts about 176 Earth days.[24] A sidereal day (the period of rotation) lasts about 58.7 Earth days.[24]
+
+Simulations indicate that the orbital eccentricity of Mercury varies chaotically from nearly zero (circular) to more than 0.45 over millions of years due to perturbations from the other planets.[24][106] 
+This was thought to explain Mercury's 3:2 spin-orbit resonance (rather than the more usual 1:1), because this state is more likely to arise during a period of high eccentricity.[107] 
+However, accurate modeling based on a realistic model of tidal response has demonstrated that Mercury was captured into the 3:2 spin-orbit state at a very early stage of its history, within 20 (more likely, 10) million years after its formation.[108]
+
+Numerical simulations show that a future secular orbital resonant perihelion interaction with Jupiter may cause the eccentricity of Mercury's orbit to increase to the point where there is a 1% chance that the planet may collide with Venus within the next five billion years.[109][110]
+
+In 1859, the French mathematician and astronomer Urbain Le Verrier reported that the slow precession of Mercury's orbit around the Sun could not be completely explained by Newtonian mechanics and perturbations by the known planets. He suggested, among possible explanations, that another planet (or perhaps instead a series of smaller 'corpuscules') might exist in an orbit even closer to the Sun than that of Mercury, to account for this perturbation.[111] (Other explanations considered included a slight oblateness of the Sun.) The success of the search for Neptune based on its perturbations of the orbit of Uranus led astronomers to place faith in this possible explanation, and the hypothetical planet was named Vulcan, but no such planet was ever found.[112]
+
+The perihelion precession of Mercury is 5,600 arcseconds (1.5556°) per century relative to Earth, or 574.10±0.65 arcseconds per century[113] relative to the inertial ICRF. Newtonian mechanics, taking into account all the effects from the other planets, predicts a precession of 5,557 arcseconds (1.5436°) per century.[113] In the early 20th century, Albert Einstein's general theory of relativity provided the explanation for the observed precession, by formalizing gravitation as being mediated by the curvature of spacetime. The effect is small: just 42.98 arcseconds per century for Mercury; it therefore requires a little over twelve million orbits for a full excess turn. Similar, but much smaller, effects exist for other Solar System bodies: 8.62 arcseconds per century for Venus, 3.84 for Earth, 1.35 for Mars, and 10.05 for 1566 Icarus.[114][115]
+
+Einstein's formula for the perihelion shift per revolution is 
+
+
+
+ϵ
+=
+24
+
+π
+
+3
+
+
+
+
+
+a
+
+2
+
+
+
+
+T
+
+2
+
+
+
+c
+
+2
+
+
+(
+1
+−
+
+e
+
+2
+
+
+)
+
+
+
+
+
+{\displaystyle \epsilon =24\pi ^{3}{\frac {a^{2}}{T^{2}c^{2}(1-e^{2})}}}
+
+, where 
+
+
+
+e
+
+
+{\displaystyle e}
+
+ is the orbital eccentricity, 
+
+
+
+a
+
+
+{\displaystyle a}
+
+ the semi-major axis, and 
+
+
+
+T
+
+
+{\displaystyle T}
+
+ the orbital period. Filling in the values gives a result of 0.1035 arcseconds per revolution or 0.4297 arcseconds per Earth year, i.e., 42.97 arcseconds per century. This is in close agreement with the accepted value of Mercury's perihelion advance of 42.98 arcseconds per century.[116]
+
+There may be scientific support, based on studies reported in March 2020, for considering that parts of the planet Mercury may have been habitable, and perhaps that life forms, albeit likely primitive microorganisms, may have existed on the planet.[117][118]
+
+Mercury's apparent magnitude is calculated to vary between −2.48 (brighter than Sirius) around superior conjunction and +7.25 (below the limit of naked-eye visibility) around inferior conjunction.[13] The mean apparent magnitude is 0.23 while the standard deviation of 1.78 is the largest of any planet. The mean apparent magnitude at superior conjunction is −1.89 while that at inferior conjunction is +5.93.[13] Observation of Mercury is complicated by its proximity to the Sun, as it is lost in the Sun's glare for much of the time. Mercury can be observed for only a brief period during either morning or evening twilight.[119]
+
+Mercury can, like several other planets and the brightest stars, be seen during a total solar eclipse.[120]
+
+Like the Moon and Venus, Mercury exhibits phases as seen from Earth. It is "new" at inferior conjunction and "full" at superior conjunction. The planet is rendered invisible from Earth on both of these occasions because of its being obscured by the Sun,[119] except its new phase during a transit.
+
+Mercury is technically brightest as seen from Earth when it is at a full phase. Although Mercury is farthest from Earth when it is full, the greater illuminated area that is visible and the opposition brightness surge more than compensates for the distance.[121] The opposite is true for Venus, which appears brightest when it is a crescent, because it is much closer to Earth than when gibbous.[121][122]
+
+Nonetheless, the brightest (full phase) appearance of Mercury is an essentially impossible time for practical observation, because of the extreme proximity of the Sun. Mercury is best observed at the first and last quarter, although they are phases of lesser brightness. The first and last quarter phases occur at greatest elongation east and west of the Sun, respectively. At both of these times Mercury's separation from the Sun ranges anywhere from 17.9° at perihelion to 27.8° at aphelion.[123][124] At greatest western elongation, Mercury rises at its earliest before sunrise, and at greatest eastern elongation, it sets at its latest after sunset.[125]
+
+Mercury can be easily seen from the tropics and subtropics more than from higher latitudes. Viewed from low latitudes and at the right times of year, the ecliptic intersects the horizon at a steep angle. Mercury is 10° above the horizon when the planet appears directly above the Sun (i.e. its orbit appears vertical) and is at maximum elongation from the Sun (28°) and also when the Sun is 18° below the horizon, so the sky is just completely dark.[d] This angle is the maximum altitude at which Mercury is visible in a completely dark sky.
+
+At middle latitudes, Mercury is more often and easily visible from the Southern Hemisphere than from the Northern. This is because Mercury's maximum western elongation occurs only during early autumn in the Southern Hemisphere, whereas its greatest eastern elongation happens only during late winter in the Southern Hemisphere.[125] In both of these cases, the angle at which the planet's orbit intersects the horizon is maximized, allowing it to rise several hours before sunrise in the former instance and not set until several hours after sundown in the latter from southern mid-latitudes, such as Argentina and South Africa.[125]
+
+An alternate method for viewing Mercury involves observing the planet during daylight hours when conditions are clear, ideally when it is at its greatest elongation. This allows the planet to be found easily, even when using telescopes with 8 cm (3.1 in) apertures. Care must be taken to ensure the instrument isn't pointed directly towards the Sun because of the risk for eye damage. This method bypasses the limitation of twilight observing when the ecliptic is located at a low elevation (e.g. on autumn evenings).
+
+Ground-based telescope observations of Mercury reveal only an illuminated partial disk with limited detail. The first of two spacecraft to visit the planet was Mariner 10, which mapped about 45% of its surface from 1974 to 1975. The second is the MESSENGER spacecraft, which after three Mercury flybys between 2008 and 2009, attained orbit around Mercury on March 17, 2011,[126] to study and map the rest of the planet.[127]
+
+The Hubble Space Telescope cannot observe Mercury at all, due to safety procedures that prevent its pointing too close to the Sun.[128]
+
+Because the shift of 0.15 revolutions in a year makes up a seven-year cycle (0.15 × 7 ≈ 1.0), in the seventh year Mercury follows almost exactly (earlier by 7 days) the sequence of phenomena it showed seven years before.[123]
+
+The earliest known recorded observations of Mercury are from the Mul.Apin tablets. These observations were most likely made by an Assyrian astronomer around the 14th century BC.[129] The cuneiform name used to designate Mercury on the Mul.Apin tablets is transcribed as Udu.Idim.Gu\u4.Ud ("the jumping planet").[e][130] Babylonian records of Mercury date back to the 1st millennium BC. The Babylonians called the planet Nabu after the messenger to the gods in their mythology.[131]
+
+The ancients knew Mercury by different names depending on whether it was an evening star or a morning star. By about 350 BC, the ancient Greeks had realized the two stars were one.[132] They knew the planet as Στίλβων Stilbōn, meaning "twinkling", and Ἑρμής Hermēs, for its fleeting motion,[133] a name that is retained in modern Greek (Ερμής Ermis).[134] The Romans named the planet after the swift-footed Roman messenger god, Mercury (Latin Mercurius), which they equated with the Greek Hermes, because it moves across the sky faster than any other planet.[132][135] The astronomical symbol for Mercury is a stylized version of Hermes' caduceus.[136]
+
+The Greco-Egyptian[137] astronomer Ptolemy wrote about the possibility of planetary transits across the face of the Sun in his work Planetary Hypotheses. He suggested that no transits had been observed either because planets such as Mercury were too small to see, or because the transits were too infrequent.[138]
+
+In ancient China, Mercury was known as "the Hour Star" (Chen-xing 辰星). It was associated with the direction north and the phase of water in the Five Phases system of metaphysics.[139] Modern Chinese, Korean, Japanese and Vietnamese cultures refer to the planet literally as the "water star" (水星), based on the Five elements.[140][141][142] Hindu mythology used the name Budha for Mercury, and this god was thought to preside over Wednesday.[143] The god Odin (or Woden) of Germanic paganism was associated with the planet Mercury and Wednesday.[144] The Maya may have represented Mercury as an owl (or possibly four owls; two for the morning aspect and two for the evening) that served as a messenger to the underworld.[145]
+
+In medieval Islamic astronomy, the Andalusian astronomer Abū Ishāq Ibrāhīm al-Zarqālī in the 11th century described the deferent of Mercury's geocentric orbit as being oval, like an egg or a pignon, although this insight did not influence his astronomical theory or his astronomical calculations.[146][147] In the 12th century, Ibn Bajjah observed "two planets as black spots on the face of the Sun", which was later suggested as the transit of Mercury and/or Venus by the Maragha astronomer Qotb al-Din Shirazi in the 13th century.[148] (Note that most such medieval reports of transits were later taken as observations of sunspots.[149])
+
+In India, the Kerala school astronomer Nilakantha Somayaji in the 15th century developed a partially heliocentric planetary model in which Mercury orbits the Sun, which in turn orbits Earth, similar to the Tychonic system later proposed by Tycho Brahe in the late 16th century.[150]
+
+The first telescopic observations of Mercury were made by Galileo in the early 17th century. Although he observed phases when he looked at Venus, his telescope was not powerful enough to see the phases of Mercury. In 1631, Pierre Gassendi made the first telescopic observations of the transit of a planet across the Sun when he saw a transit of Mercury predicted by Johannes Kepler. In 1639, Giovanni Zupi used a telescope to discover that the planet had orbital phases similar to Venus and the Moon. The observation demonstrated conclusively that Mercury orbited around the Sun.[24]
+
+A rare event in astronomy is the passage of one planet in front of another (occultation), as seen from Earth. Mercury and Venus occult each other every few centuries, and the event of May 28, 1737 is the only one historically observed, having been seen by John Bevis at the Royal Greenwich Observatory.[151] The next occultation of Mercury by Venus will be on December 3, 2133.[152]
+
+The difficulties inherent in observing Mercury mean that it has been far less studied than the other planets. In 1800, Johann Schröter made observations of surface features, claiming to have observed 20-kilometre-high (12 mi) mountains. Friedrich Bessel used Schröter's drawings to erroneously estimate the rotation period as 24 hours and an axial tilt of 70°.[153] In the 1880s, Giovanni Schiaparelli mapped the planet more accurately, and suggested that Mercury's rotational period was 88 days, the same as its orbital period due to tidal locking.[154] This phenomenon is known as synchronous rotation. The effort to map the surface of Mercury was continued by Eugenios Antoniadi, who published a book in 1934 that included both maps and his own observations.[81] Many of the planet's surface features, particularly the albedo features, take their names from Antoniadi's map.[155]
+
+In June 1962, Soviet scientists at the Institute of Radio-engineering and Electronics of the USSR Academy of Sciences, led by Vladimir Kotelnikov, became the first to bounce a radar signal off Mercury and receive it, starting radar observations of the planet.[156][157][158] Three years later, radar observations by Americans Gordon H. Pettengill and Rolf B. Dyce, using the 300-meter Arecibo Observatory radio telescope in Puerto Rico, showed conclusively that the planet's rotational period was about 59 days.[159][160] The theory that Mercury's rotation was synchronous had become widely held, and it was a surprise to astronomers when these radio observations were announced. If Mercury were tidally locked, its dark face would be extremely cold, but measurements of radio emission revealed that it was much hotter than expected. Astronomers were reluctant to drop the synchronous rotation theory and proposed alternative mechanisms such as powerful heat-distributing winds to explain the observations.[161]
+
+Italian astronomer Giuseppe Colombo noted that the rotation value was about two-thirds of Mercury's orbital period, and proposed that the planet's orbital and rotational periods were locked into a 3:2 rather than a 1:1 resonance.[162] Data from Mariner 10 subsequently confirmed this view.[163] This means that Schiaparelli's and Antoniadi's maps were not "wrong". Instead, the astronomers saw the same features during every second orbit and recorded them, but disregarded those seen in the meantime, when Mercury's other face was toward the Sun, because the orbital geometry meant that these observations were made under poor viewing conditions.[153]
+
+Ground-based optical observations did not shed much further light on Mercury, but radio astronomers using interferometry at microwave wavelengths, a technique that enables removal of the solar radiation, were able to discern physical and chemical characteristics of the subsurface layers to a depth of several meters.[164][165] Not until the first space probe flew past Mercury did many of its most fundamental morphological properties become known. Moreover, recent technological advances have led to improved ground-based observations. In 2000, high-resolution lucky imaging observations were conducted by the Mount Wilson Observatory 1.5 meter Hale telescope. They provided the first views that resolved surface features on the parts of Mercury that were not imaged in the Mariner 10 mission.[166] Most of the planet has been mapped by the Arecibo radar telescope, with 5 km (3.1 mi) resolution, including polar deposits in shadowed craters of what may be water ice.[167]
+
+Reaching Mercury from Earth poses significant technical challenges, because it orbits so much closer to the Sun than Earth. A Mercury-bound spacecraft launched from Earth must travel over 91 million kilometres (57 million miles) into the Sun's gravitational potential well. Mercury has an orbital speed of 48 km/s (30 mi/s), whereas Earth's orbital speed is 30 km/s (19 mi/s). Therefore, the spacecraft must make a large change in velocity (delta-v) to enter a Hohmann transfer orbit that passes near Mercury, as compared to the delta-v required for other planetary missions.[169]
+
+The potential energy liberated by moving down the Sun's potential well becomes kinetic energy; requiring another large delta-v change to do anything other than rapidly pass by Mercury. To land safely or enter a stable orbit the spacecraft would rely entirely on rocket motors. Aerobraking is ruled out because Mercury has a negligible atmosphere. A trip to Mercury requires more rocket fuel than that required to escape the Solar System completely. As a result, only two space probes have visited it so far.[170] A proposed alternative approach would use a solar sail to attain a Mercury-synchronous orbit around the Sun.[171]
+
+The first spacecraft to visit Mercury was NASA's Mariner 10 (1974–1975).[132] The spacecraft used the gravity of Venus to adjust its orbital velocity so that it could approach Mercury, making it both the first spacecraft to use this gravitational "slingshot" effect and the first NASA mission to visit multiple planets.[169] Mariner 10 provided the first close-up images of Mercury's surface, which immediately showed its heavily cratered nature, and revealed many other types of geological features, such as the giant scarps that were later ascribed to the effect of the planet shrinking slightly as its iron core cools.[172] Unfortunately, the same face of the planet was lit at each of Mariner 10's close approaches. This made close observation of both sides of the planet impossible,[173] and resulted in the mapping of less than 45% of the planet's surface.[174]
+
+The spacecraft made three close approaches to Mercury, the closest of which took it to within 327 km (203 mi) of the surface.[175] At the first close approach, instruments detected a magnetic field, to the great surprise of planetary geologists—Mercury's rotation was expected to be much too slow to generate a significant dynamo effect. The second close approach was primarily used for imaging, but at the third approach, extensive magnetic data were obtained. The data revealed that the planet's magnetic field is much like Earth's, which deflects the solar wind around the planet. For many years after the Mariner 10 encounters, the origin of Mercury's magnetic field remained the subject of several competing theories.[176][177]
+
+On March 24, 1975, just eight days after its final close approach, Mariner 10 ran out of fuel. Because its orbit could no longer be accurately controlled, mission controllers instructed the probe to shut down.[178] Mariner 10 is thought to be still orbiting the Sun, passing close to Mercury every few months.[179]
+
+A second NASA mission to Mercury, named MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging), was launched on August 3, 2004. It made a fly-by of Earth in August 2005, and of Venus in October 2006 and June 2007 to place it onto the correct trajectory to reach an orbit around Mercury.[180] A first fly-by of Mercury occurred on January 14, 2008, a second on October 6, 2008,[181] and a third on September 29, 2009.[182] Most of the hemisphere not imaged by Mariner 10 was mapped during these fly-bys. The probe successfully entered an elliptical orbit around the planet on March 18, 2011. The first orbital image of Mercury was obtained on March 29, 2011. The probe finished a one-year mapping mission,[181] and then entered a one-year extended mission into 2013. In addition to continued observations and mapping of Mercury, MESSENGER observed the 2012 solar maximum.[183]
+
+The mission was designed to clear up six key issues: Mercury's high density, its geological history, the nature of its magnetic field, the structure of its core, whether it has ice at its poles, and where its tenuous atmosphere comes from. To this end, the probe carried imaging devices that gathered much-higher-resolution images of much more of Mercury than Mariner 10, assorted spectrometers to determine abundances of elements in the crust, and magnetometers and devices to measure velocities of charged particles. Measurements of changes in the probe's orbital velocity were expected to be used to infer details of the planet's interior structure.[184] MESSENGER's final maneuver was on April 24, 2015, and it crashed into Mercury's surface on April 30, 2015.[185][186][187] The spacecraft's impact with Mercury occurred near 3:26 PM EDT on April 30, 2015, leaving a crater estimated to be 16 m (52 ft) in diameter.[188]
+
+The European Space Agency and the Japanese Space Agency developed and launched a joint mission called BepiColombo, which will orbit Mercury with two probes: one to map the planet and the other to study its magnetosphere.[189] Launched on October 20, 2018, BepiColombo is expected to reach Mercury in 2025.[190] It will release a magnetometer probe into an elliptical orbit, then chemical rockets will fire to deposit the mapper probe into a circular orbit. Both probes will operate for one terrestrial year.[189] The mapper probe carries an array of spectrometers similar to those on MESSENGER, and will study the planet at many different wavelengths including infrared, ultraviolet, X-ray and gamma ray.[191]
+
+Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Observable universe → UniverseEach arrow (→) may be read as "within" or "part of".
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+The Aral Sea (Aral /ˈærəl/;[4] Kazakh: Aral teńizi, Арал теңізі, Uzbek: Orol dengizi, Орол денгизи, Karakalpak: Aral ten'izi, Арал теңизи) was an endorheic lake lying between Kazakhstan (Aktobe and Kyzylorda Regions in the north) and Uzbekistan (Karakalpakstan autonomous region in the south). The name roughly translates as "Sea of Islands", referring to over 1,100 islands that had dotted its waters; in the Mongolic languages  and Turkic language aral means "island, archipelago". The Aral Sea drainage basin encompasses Uzbekistan and parts of Tajikistan, Turkmenistan, Kyrgyzstan, Kazakhstan, Afghanistan, and Iran.[1]
+
+Formerly the fourth largest lake in the world with an area of 68,000 km2 (26,300 sq mi), the Aral Sea has been shrinking since the 1960s after the rivers that fed it were diverted by Soviet irrigation projects. By 1997, it had declined to 10% of its original size, splitting into four lakes: the North Aral Sea, the eastern and western basins of the once far larger South Aral Sea, and one smaller intermediate lake.[5] By 2009, the southeastern lake had disappeared and the southwestern lake had retreated to a thin strip at the western edge of the former southern sea; in subsequent years, occasional water flows have led to the southeastern lake sometimes being replenished to a small degree.[6] Satellite images taken by NASA in August 2014 revealed that for the first time in modern history the eastern basin of the Aral Sea had completely dried up.[7] The eastern basin is now called the Aralkum Desert.
+
+In an ongoing effort in Kazakhstan to save and replenish the North Aral Sea, the Dike Kokaral dam project was completed in 2005; in 2008, the water level in this lake had risen by 12 m (39 ft) compared to 2003.[8] Salinity has dropped, and fish are again present in sufficient numbers for some fishing to be viable.[9] The maximum depth of the North Aral Sea is 42 m (138 ft) (as of 2008[update]).[2]
+
+The shrinking of the Aral Sea has been called "one of the planet's worst environmental disasters".[10] The region's once-prosperous fishing industry has been devastated, bringing unemployment and economic hardship. The water from the diverted Syr Darya river is used to irrigate about two million hectares (5,000,000 acres) of farmland in the Ferghana Valley.[11]  The Aral Sea region is also heavily polluted, with consequential serious public health problems. UNESCO added the historical documents concerning the development of the Aral Sea to its Memory of the World Register as a unique resource to study this "environmental tragedy".
+
+Geographer Nick Middleton believes that the Amu Darya did not flow into the shallow depression that now forms the Aral Sea until the beginning of the Holocene,[12] and it is known that the Amu Darya flowed into the Caspian Sea via the Uzboy channel until the Holocene.[12] The Syr Darya formed a large lake in the Kyzyl Kum during the Pliocene known as the Mynbulak depression.[13]
+
+Despite its formerly vast size, the Aral Sea had relatively low indigenous biodiversity. Native fish species of the lake included ship sturgeon (Acipenser nudiventris), all three Pseudoscaphirhynchus sturgeon species, Aral trout (Salmo trutta aralensis), northern pike (Esox lucius), ide (Leuciscus idus oxianus), asp (Aspius aspius iblioides), common rudd (Scardinius erythropthalmus), Turkestan barbel (Luciobarbus capito conocephalus), Aral barbel (L. brachycephalus brachycephalus), common bream (Abramis brama orientalis), white-eyed bream (Ballerus sapa aralensis), Danube bleak (Chalcalburnus chalcoides aralensis), ziege (Pelecus cultratus), crucian carp (Carassius carassius gibelio), common carp (Cyprinus carpio aralensis), Wels catfish (Silurus glanis), Ukrainian stickleback (Pungitius platygaster aralensis), zander (Sander lucioperca), European perch (Perca fluviatilis), and Eurasian ruffe (Gymnocephalus cernuus). All these fish aside from the stickleback lived an anadramous or semi-anadromous lifestyle.[14][15] Following the salinity increase and drying of the lake, the Aral trout, ruffe, Turkestan barbel and all sturgeon species were entirely extirpated and have not since returned due to dams blocking their migration routes, with the Aral trout and Syr Darya sturgeon (Pseudoscaphirhynchus fedtschenkoi) possibly being driven to extinction due to their restricted range.[15][16] All other native fish barring the stickleback (which persisted even during the lake's shrinkage and salinity increase) were also extirpated, but have since returned to the North Aral Sea following its recovery from the 1990s onwards.[14]
+
+Numerous other mostly salt-tolerant fish species were purposefully or inadvertently introduced during the 1960s, due to the increasing salinity of the lake from hydropower and irrigation projects that reduced the flow of fresh water. These include the Baltic herring (Clupea harengus membras), big-scale sand smelt (Atherina boyeri caspia), black-striped pipefish (Syngnatus abaster caspius), Caucasian dwarf goby (Knipowitschia caucasica), monkey goby (Neogobius fluviatilis), round goby (N. melanostomus), Syrman goby (N. syrman), bighead goby (Ponticola kessleri), tubenose goby (Proterorchinus marmoratus),  grass carp (Ctenopharyngodon idella), silver carp (Hypophtalmichthys molitrix), bighead carp (H. nobilis), black carp (Mylopharyngodon piceus) and northern snakehead (Channa argus warpachowski). Prior to the introduction of the herring, sand smelt, and gobies, there were no planktivorous fish in the lake; these introduced species led to a collapse in the lake's population of zooplankton, which also led to a collapse in the population of herring and sand smelt, from which neither species have since recovered.[14] All introduced species aside from the carp, snakehead, and (possibly) pipefish survived the lake's shrinkage and salinity increase, and during this time period the European flounder (Platichthys flesus) was also introduced to the lake to revive fisheries. The extirpated species (aside from possibly the pipefish) returned to the North Aral Sea following its recovery. Herring, sand smelt, gobies, and flounder also managed to persist in the South Aral Sea, but its increasing salinity led all but the gobies to be eventually extirpated from the area.[14]
+
+The decrease in salinity of the North Aral Sea from the 1990s onwards has led to a recovery of its zooplankton population, with many extirpated crustacean and rotifer species returning naturally via the Syr Darya River. The extirpated zebra mussel (Dreissena polymorpha aralensis) has also been reintroduced to the northern lake. In contrast, only a few invertebrates, mainly nematodes, some rotifers, and parthenogenic brine shrimp, still exist in or have established populations in the South Aral Sea.[14]
+
+Most of the area around the Aral Sea was inhabited by desert nomads who left few written records. However, the Oxus delta to the south has a long history under the name of Khwarezm. It was once the westernmost border of China during the Tang dynasty.[17]
+
+The Aral Sea has undergone multiple phases of sea level rise and fall. Climate-driven shifts have contributed to these changes in sea level.[18] To be specific, inflow rates from the Amu Darya and Syr Darya are affected by glacial melt rates at the rivers' headwaters as well as precipitation within the river basins – cold, dry climates restrict both processes.[18] But artificial irrigation systems have also impacted the Aral, beginning in ancient times and continuing to the present.[19][20]
+
+Russian naval presence on the Aral Sea started in 1847, with the founding of Raimsk, which was soon renamed Fort Aralsk, near the mouth of the Syr Darya. Soon, the Imperial Russian Navy started deploying its vessels on the sea. Owing to the Aral Sea basin not being connected to other bodies of water, the vessels had to be disassembled in Orenburg on the Ural River, shipped overland to Aralsk (presumably by a camel caravan), and then reassembled. The first two ships, assembled in 1847, were the two-masted schooners named Nikolai and Mikhail. The former was a warship; the latter was a merchant vessel meant to serve the establishment of the fisheries on the great lake. In 1848, these two vessels surveyed the northern part of the sea. In the same year, a larger warship, the Constantine, was assembled. Commanded by Lt. Alexey Butakov (Алексей Бутаков), the Constantine completed the survey of the entire Aral Sea over the next two years.[21]
+The exiled Ukrainian poet and painter Taras Shevchenko participated in the expedition, and painted a number of sketches of the Aral Sea coast.[22]
+
+For the navigation season of 1851, two newly built steamers arrived from Sweden, again by caravan from Orenburg. As the geological surveys had found no coal deposits in the area, the Military Governor-General of Orenburg Vasily Perovsky ordered "as large as possible supply" of saxaul (Haloxylon ammodendron, a desert shrub, akin to the creosote bush) to be collected in Aralsk for use by the new steamers. Unfortunately, saxaul wood did not turn out a very suitable fuel, and in the later years, the Aral Flotilla was provisioned, at substantial cost, by coal from the Donbass.[21] (This was part of the Russian conquest of Turkestan.)
+
+In the early 1960s,[23] the Soviet government decided the two rivers that fed the Aral Sea, the Amu Darya in the south and the Syr Darya in the east, would be diverted to irrigate the desert, in an attempt to grow rice, melons, cereals and cotton.[24] This was part of the Soviet plan for cotton, or "white gold", to become a major export. This temporarily succeeded, and in 1988, Uzbekistan was the world's largest exporter of cotton.[25] Cotton production in Uzbekistan is still important to the national economy of the country.[26][27] It is Uzbekistan's main cash crop, accounting for 17% of its exports in 2006.[28]
+
+Construction of irrigation canals began on a large scale in the 1930s, and was accelerated into a greatly increased scale of construction in the 1960s.[29] Many of the canals were poorly built, allowing water to leak or evaporate. From the Qaraqum Canal, the largest in Central Asia, perhaps 30 to 75% of the water went to waste.[24] In 2012, it was estimated that only 12% of Uzbekistan's irrigation canal length is waterproofed.[29] Of the 47,750 km of interfarm irrigation channels in the basin, only 28% have anti-infiltration linings. Only 77% of farm intakes have flow gauges, and of the 268,500 km of onfarm channels, only 21% have anti-infiltration linings, which retain on average 15% more water than unlined channels.[30]
+
+By 1960, between 20 and 60 km3 (4.8 and 14.4 cu mi) of water each year was going to the land instead of the sea. Most of the sea's water supply had been diverted, and in the 1960s, the Aral Sea began to shrink. From 1961 to 1970, the Aral's level fell at an average of 20 cm (7.9 in) a year; in the 1970s, the average rate nearly tripled to 50–60 cm (20–24 in) per year, and by the 1980s, it continued to drop, now with a mean of 80–90 cm (31–35 in) each year. The rate of water use for irrigation continued to increase; the amount of water taken from the rivers doubled between 1960 and 2000, and cotton production nearly doubled in the same period.[citation needed] In the first half of the 20th century prior to the irrigation, the sea's water level above sea level held steady at 53 m; this has changed drastically by 2010, when the large Aral was 27 m and the small Aral 43 m above sea level.[31]
+
+The disappearance of the lake was no surprise to the Soviets; they expected it to happen long before. As early as 1964, Aleksandr Asarin at the Hydroproject Institute pointed out that the lake was doomed, explaining, "It was part of the five-year plans, approved by the council of ministers and the Politburo. Nobody on a lower level would dare to say a word contradicting those plans, even if it was the fate of the Aral Sea."[32]
+
+The reaction to the predictions varied. Some Soviet experts apparently considered the Aral to be "nature's error", and a Soviet engineer said in 1968, "it is obvious to everyone that the evaporation of the Aral Sea is inevitable."[33] On the other hand, starting in the 1960s, a large-scale project was proposed to redirect part of the flow of the rivers of the Ob basin to Central Asia over a gigantic canal system. Refilling of the Aral Sea was considered as one of the project's main goals. However, due to its staggering costs and the negative public opinion in Russia proper, the federal authorities abandoned the project by 1986.[34]
+
+From 1960 to 1998, the sea's surface area shrank by about 60%, and its volume by 80%. In 1960, the Aral Sea had been the world's fourth-largest lake, with an area around 68,000 km2 (26,000 sq mi) and a volume of 1,100 km3 (260 cu mi); by 1998, it had dropped to 28,687 km2 (11,076 sq mi) and eighth largest. The salinity of the Aral Sea also increased: by 1990 it was around 376 g/L.[5] (By comparison, the salinity of ordinary seawater is typically around 35 g/L; the Dead Sea's salinity varies between 300 and 350 g/L.)
+
+In 1987, the continuing shrinkage split the lake into two separate bodies of water, the North Aral Sea (the Lesser Sea, or Small Aral Sea) and the South Aral Sea (the Greater Sea, or Large Aral Sea). In June 1991, Uzbekistan gained independence from the Soviet Union. Craig Murray, a UK ambassador to Uzbekistan in 2002, described the independence as a way for Islam Karimov to consolidate his power rather than a move away from a Soviet-style economy and its philosophy of exploitation of the land. Murray attributes the shrinkage of the Aral Sea in the 1990s to Karimov's cotton policy. The government maintained an enormous irrigation system which Murray described as massively wasteful, with most of the water being lost through evaporation before reaching the cotton.[clarification needed] Crop rotation was not used, and the depleted soil and monoculture required massive quantities of pesticides and fertilizer. The runoff from the fields washed these chemicals into the shrinking sea, creating severe pollution and health problems. As the water supply of the Aral Sea decreased, the demand for cotton increased and the government reacted by pouring more pesticides and fertilizer onto the land. Murray compared the system to the slavery system in the pre-Civil War United States; forced labor was used, and profits were siphoned off by the powerful and well-connected.[35]
+
+By summer 2003, the South Aral Sea was vanishing faster than predicted. In the deepest parts of the sea, the bottom waters were saltier than the top, and not mixing. Thus, only the top of the sea was heated in the summer, and it evaporated faster than would otherwise be expected. In 2003, the South Aral further divided into eastern and western basins.
+
+In 2004, the Aral Sea's surface area was only 17,160 km2 (6,630 sq mi), 25% of its original size, and a nearly fivefold increase in salinity had killed most of its natural flora and fauna. By 2007, the sea's area had further shrunk to 10% of its original size.  The decline of the North Aral has now been partially reversed following construction of a dam (see below), but the remnants of the South Aral continue to disappear and its drastic shrinkage has created the Aralkum, a desert on the former lake bed.
+
+The inflow of groundwater into the South Aral Sea will probably not in itself be able to stop the desiccation, especially without a change in irrigation practices.[36] This inflow of about 4 km3 (0.96 cu mi) per year is larger than previously estimated. The groundwater originates in the Pamirs and Tian Shan Mountains and finds its way through geological layers to a fracture zone[37] at the bottom of the Aral.
+
+The Aral Sea from space, North at bottom, August 1985
+
+The Aral Sea from space, North at bottom, August 1997
+
+The Aral Sea from space, North at top, August 2009
+
+The Aral Sea from space, North at top, August 2017
+
+April 2018
+
+The Aral Sea is considered an example of ecosystem collapse.[38] The ecosystems of the Aral Sea and the river deltas feeding into it have been nearly destroyed, not least because of the much higher salinity. The receding sea has left huge plains covered with salt and toxic chemicals resulting from weapons testing, industrial projects, and pesticides and fertilizer runoff.  Due to the shrinking water source and subsequent worsening water and soil quality, pesticides were increasingly used starting in the 1960s to increase cotton yields, which further polluted the water with toxins such as DDTs.[39] Furthermore, “PCB-compounds and heavy metals” from industrial pollution contaminated both water and soil.[40] Due to the minimal amount of water left in the Aral sea, concentrations of these pollutants have increased drastically in both the water and soil. These substances form wind-borne toxic dust that spreads throughout the region. People living near the Aral Sea come in contact with pollutants through drinking water and inhalation of contaminated dust.[41] Furthermore, due to the presence in drinking water, the toxins have entered the food chain.[40] As a result, the land around the Aral Sea is heavily polluted, and the people living in the area are suffering from a lack of fresh water and health problems, including high rates of certain forms of cancer and lung diseases. Respiratory illnesses, including tuberculosis (most of which is drug resistant) and cancer, digestive disorders, anaemia, and infectious diseases are common ailments in the region. Liver, kidney, and eye problems can also be attributed to the toxic dust storms. All of this has resulted in an unusually high fatality rate among vulnerable parts of the population: the child mortality rate is 75 in every 1,000 newborns, and maternity death is 12 in every 1,000 women.[42][43]
+
+The dust storms also contribute to water shortages through salt deposition.[37] The overuse of pesticides on crops to preserve yields has made this worse, with pesticide use far beyond health limits.[37] Crops in the region are destroyed by salt being deposited onto the land, and fields are being flushed with water at least four times per day to try to remove the salinity from the soils.[37] The land is decaying, causing few crops to grow besides fodder, which is what the farmers in Kazakhstan are now deciding to seed.[44] Large bodies of water, like the Aral Sea, can moderate a region's climate by altering moisture and energy balance.[45] Loss of water in Aral Sea has changed surface temperatures and wind patterns. This has resulted in hotter summers and cooler winters (an estimated 2˚C-6˚C change in either direction) and the emergence of dust storms over the area.[45]
+
+The Aral Sea fishing industry, which in its heyday employed some 40,000 and reportedly produced one-sixth of the Soviet Union's entire fish catch, has been devastated. In the 1980s commercial harvests were becoming unsustainable, and by 1987 commercial harvest became nonexistent. Due to the declining sea levels, salinity levels became too high for the 20 native fish species to survive. The only fish that could survive the high-salinity levels was flounder.  Due to the declining sea levels, former fishing towns along the original shores have become ship graveyards.[46] Aral, originally the main fishing port, is now several kilometres from the sea and has seen its population decline dramatically since the beginning of the crisis.[47] The town of Moynaq in Uzbekistan had a thriving harbour and fishing industry that employed about 30,000 people;[48] now it lies kilometres from the shore. Fishing boats lie scattered on the dry land that was once covered by water; many have been there for 20 years.
+
+The South Aral Sea remains too saline to host any species other than halotolerant organisms.[49] The South Aral has been incapable of supporting fish since the late 1990s, when the flounder were killed by rising salinity levels.[50]
+
+Also destroyed is the muskrat-trapping industry in the deltas of the Amu Darya and Syr Darya, which used to yield as many as 500,000 pelts a year.[32]
+
+Aral Sea dust storm, March 2010
+
+Abandoned ship near Aral, Kazakhstan
+
+A former harbour in the city of Aral
+
+Local Kazakh fisherman harvesting the day's catch
+
+Women and children are the most vulnerable populations in this environmental health crisis due to the highly polluted and salinated water used for drinking and the dried seabed.[51] Toxins from pesticides have been found in blood and breast milk of mothers, specifically organochlorides, polychlorinated biphenyl compounds (PCBs), DDT compounds, and TCDD.[52][40] These toxins can be, and often are, passed on to the children of these mothers resulting in low birthweight children and children with abnormalities. The rate of infants being born with abnormalities is five times higher in this region than in European countries.[53] The Aral Sea region has 26% of its children born at low birthweight, which is two standard deviations away from a national study population gathered by the WHO.[54] Exposures to toxic chemicals from the dry seabed and polluted water have caused other health issues in women in children. Renal tubular dysfunction has become a large health concern in children in the Aral Sea region as it is showing extremely high prevalence rates. Renal tubular dysfunction can also be related to growth and developmental stunting.[55] This, in conjunction with the already high rate of low birth weight children and children born with abnormalities, poses severe negative health effects and outcomes on children. These issues are compounded by the lack of research of maternal and child health effects caused by the demise of the Aral Sea. For example,  only 26 English-language peer-reviewed articles and four reports on children's health were produced between 1994 and 2008.[56] In addition, there is a lack of health infrastructure and resources in the Aral Sea region to combat the health issues that have arisen.[57]
+
+There is a lack of medication and equipment in many medical facilities, so health professionals do not have access to the necessary supplies to do their jobs in the Kazakhstan and Uzbekistan regions.[58] There is also meager development of a health information system that would allow for extensive research or surveillance of emerging health issues due to Aral sea issues.[58] An absence of a primary care approach in the health systems of this region also hinders services and access that could prevent and treat issues stemming from the Aral Sea crisis, especially in women and children.[58]
+
+The impoverished are also particularly vulnerable to the environmental and health related effects of changes to the Aral Sea. These populations were most likely to reside downstream from the Basin and in former coastal communities.[59] They were also among the first to be detrimentally affected, representing at least 4.4 million people in the region.[60] Considered to have the worst health in this region, their plight was not helped when their fishery livelihoods vanished with the decreasing levels of water and loss of many aquatic species.[61] Thus, those in poverty are entrenched in a vicious cycle.
+
+Many different solutions to the problems have been suggested over the years, varying in feasibility and cost, including:
+
+In January 1994, Kazakhstan, Uzbekistan, Turkmenistan, Tajikistan, and Kyrgyzstan signed a deal to pledge 1% of their budgets to help the sea recover.
+
+In March 2000, UNESCO presented their "Water-related vision for the Aral Sea basin for the year 2025"[66] at the second World Water Forum in The Hague. This document was criticized for setting unrealistic goals and for giving insufficient attention to the interests of the area immediately around the former lakesite, implicitly giving up on the Aral Sea and the people living on the Uzbek side of the lake.[67]
+
+By 2006, the World Bank's restoration projects, especially in the North Aral, were giving rise to some unexpected, tentative relief in what had been an extremely pessimistic picture.[68]
+
+The future of the Aral Sea and the responsibility for its survival are now in the hands of the five countries: Kazakhstan, Uzbekistan, Tajikistan, Kyrgyzstan, and Turkmenistan. In 1994, they adopted the Aral Sea Basin Programme.[69]  The Programme's four objectives are:
+
+The first phase of the plan effectively began with the first involvement from the World Bank in 1992, and was in operation until 1997.  It was ineffectual for a number of reasons, but mainly because it was focused on improving directly the land around the Aral Sea, whilst not intervening in the water usage upstream. There was considerable concern amongst the Central Asian governments, which realised the importance of the Aral Sea in the ecosystem and the economy of Central Asia, and they were prepared to cooperate, but they found it difficult to implement the procedures of the plan.[citation needed]
+
+This is due in part to a lack of co-operation among the affected people. The water flowing into the Aral Sea has long been considered an important commodity, and trade agreements have been made to supply the downstream communities with water in the spring and summer months for irrigation. In return, they supply the upstream countries with fuel during the winter, instead of storing water during the warm months for hydroelectric purposes in winter. However, very few legal obligations are binding these contracts, particularly on an international stage.[citation needed]
+
+Phase Two of the Aral Sea Basin programme followed in 1998 and ran for five years. The main shortcomings of phase two were due to its lack of integration with the local communities involved. The scheme was drawn up by the World Bank, government representatives, and various technical experts, without consulting those who would be affected. An example of this was the public awareness initiatives, which were seen as propagandist attempts by people with little care or understanding of their situation.  These failures have led to the introduction of a new plan, funded by a number of institutions, including the five countries involved and the World Bank.
+
+In 1997, a new plan was conceived which would continue with the previous restoration efforts of the Aral Sea. The main aims of this phase are to improve the irrigation systems currently in place, whilst targeting water management at a local level. The largest project in this phase is the North Aral Sea Project, a direct effort to recover the northern region of the Aral Sea. The North Aral Sea Project's main initiative is the construction of a dam across the Berg Strait, a deep channel which connects the North Aral Sea to the South Aral Sea. The Kok-Aral Dam is 13 kilometres (8 miles) long and has capacity for over 29 cubic kilometres of water to be stored in the North Aral Sea, whilst allowing excess to overflow into the South Aral Sea.
+
+On 6 October 2002, the Heads of States met again to revise the ASBP program.  ASBP-2 was in place from 2003 to 2010. The main purpose of the ASBP-2 was to set up projects that covered a vast amount of environmental, socioeconomic and water management issues. The ASBP-2 was financed by organization such as the UNDP, World Bank, USAID, Asian Development Bank, and the governments of Switzerland, Japan, Finland, Norway and others.  Over 2 billion US Dollars was provided by the IFAS country members to the program.[70]
+
+On 28 April 2009 the Head of States came together with the Interstate commission for Water Coordination, Interstate Commission for Sustainable Development and National Experts and donors to develop the ASBP-3.  This Program was in effect from 2011- 2015.  The main purpose of the ASBP-3 was to improve the environmental and socio-economic situation of the Aral Sea Basin. The four program prioritizes were:[71]
+
+Direction One's main purpose is to propose program that focus on addressing transboundary water resources management, establishment of monitoring systems and addressing safety concerns in water facilities. Examples of programs that have been proposed include:[72]
+
+Directions two's main focus is on addressing the issues related to environmental protection and improvement of the environment. Areas of interest include:[73]
+
+Direction three looks to address socio-economic issues by focusing on education and public health, improving unemployment rates, improving water systems, increasing sustainable development and improving living conditions.  The expected outputs are:[74]
+
+Direction Four aims to address issues related to institutional development and the development of policies and strategies that relate to sustainable development and public awareness.  Expected outputs include:[75]
+
+Work is being done to restore in part the North Aral Sea. Irrigation works on the Syr Darya have been repaired and improved to increase its water flow, and in October 2003, the Kazakh government announced a plan to build Dike Kokaral, a concrete dam separating the two halves of the Aral Sea. Work on this dam was completed in August 2005; since then, the water level of the North Aral has risen, and its salinity has decreased. As of 2006[update], some recovery of sea level has been recorded, sooner than expected.[76] "The dam has caused the small Aral's sea level to rise swiftly to 38 m (125 ft), from a low of less than 30 m (98 ft), with 42 m (138 ft) considered the level of viability."[77]
+
+Economically significant stocks of fish have returned, and observers who had written off the North Aral Sea as an environmental disaster were surprised by unexpected reports that, in 2006, its returning waters were already partly reviving the fishing industry and producing catches for export as far as Ukraine. The improvements to the fishing industry were largely due to the drop in the average salinity of the sea from 30 grams to 8 grams per liter; this drop in salinity prompted the return of almost 24 freshwater species.[46] The restoration also reportedly gave rise to long-absent rain clouds and possible microclimate changes, bringing tentative hope to an agricultural sector swallowed by a regional dustbowl, and some expansion of the shrunken sea.[78]
+
+"The sea, which had receded almost 100 km (62 mi) south of the port-city of Aralsk, is now a mere 25 km (16 mi) away." The Kazakh Foreign Ministry stated that "The North Aral Sea's surface increased from 2,550 square kilometers (980 sq mi) in 2003 to 3,300 square kilometers (1,300 sq mi) in 2008. The sea's depth increased from 30 meters (98 ft) in 2003 to 42 meters (138 ft) in 2008."[2] Now, a second dam is to be built based on a World Bank loan to Kazakhstan, with the start of construction initially slated for 2009 and postponed to 2011, to further expand the shrunken Northern Aral,[79][failed verification] eventually reducing the distance to Aralsk to only 6 km (3.7 mi). Then, it was planned to build a canal spanning the last 6 km, to reconnect the withered former port of Aralsk to the sea.[80]
+
+The South Aral Sea, half of which lies in Uzbekistan, was abandoned to its fate. Most of Uzbekistan's part of the Aral Sea is completely shriveled up. Only excess water from the North Aral Sea is periodically allowed to flow into the largely dried-up South Aral Sea through a sluice in the dyke.[81]  Discussions had been held on recreating a channel between the somewhat improved North and the desiccated South, along with uncertain wetland restoration plans throughout the region, but political will is lacking.[76] Unlike Kazakhstan, which has partially revived its part of the Aral Sea, Uzbekistan shows no signs in abandoning the Amu Darya river to irrigate their cotton, and is moving toward oil exploration in the drying South Aral seabed.[80]
+
+Attempts to mitigate the effects of desertification include planting vegetation in the newly exposed seabed; however, intermittent flooding of the eastern basin is likely to prove problematic for any development. Redirecting what little flow there is from the Amu Darya to the western basin may salvage fisheries there while relieving the flooding of the eastern basin.[82]
+
+The Interstate Commission for Water Coordination of Central Asia (ICWC) was formed on 18 February 1992 to formally unite Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan in the hopes of solving environmental, as well as socioeconomic problems in the Aral Sea region. The River Basin Organizations (the BVOs) of the Syr Darya and Amu Darya rivers were institutions called upon by the ICWC to help manage water resources. According to the ICWC,[83] the main objectives of the body are:
+
+The International Fund for Saving the Aral Sea (IFAS) was developed on 23 March 1993, by the ICWC to raise funds for the projects under Aral Sea Basin programmes. The IFAS was meant to finance programmes to save the sea and improve on environmental issues associated with the basin's drying. This programme has had some success with joint summits of the countries involved and finding funding from the World Bank to implement projects; however, it faces many challenges, such as enforcement and slowing progress.[84]
+
+Vozrozhdeniya (Rebirth) Island is a former island of the Aral Sea or South Aral Sea. Due to the ongoing shrinkage of the Aral, it became first a peninsula in mid-2001 and finally part of the mainland.[85] Other islands like Kokaral and Barsa-Kelmes shared a similar fate. Since the disappearance of the Southeast Aral in 2008, Vozrozhdeniya effectively no longer exists as a distinct geographical feature. The area is now shared by Kazakhstan and Uzbekistan.
+
+In 1948, a top-secret Soviet bioweapons laboratory was established on the island, in the centre of the Aral Sea which is now disputed territory between Kazakhstan and Uzbekistan. The exact history, functions and current status of this facility are still unclear, but bio-agents tested there included Bacillus anthracis, Coxiella burnetii, Francisella tularensis, Brucella suis, Rickettsia prowazekii, Variola major (smallpox), Yersinia pestis, botulinum toxin, and Venezuelan equine encephalitis virus.[86] In 1971, weaponized smallpox from the island reached a nearby ship, which then allowed the virus to spread to the city of Aral. Ten people there were infected, of whom three died, and a massive vaccination effort involving 50,000 inhabitants ensued (see Aral smallpox incident). The bioweapons base was abandoned in 1992 following the disintegration of the Soviet Union the previous year. Scientific expeditions proved this had been a site for production, testing and later dumping of pathogenic weapons. In 2002, through a project organized by the United States and with Uzbekistan's assistance, 10 anthrax burial sites were decontaminated. According to the Kazakh Scientific Center for Quarantine and Zoonotic Infections, all burial sites of anthrax were decontaminated.[87]
+
+Ergash Shaismatov, the deputy prime minister of Uzbekistan, announced on 30 August 2006, that the Uzbek government and an international consortium consisting of state-run Uzbekneftegaz, LUKoil Overseas, Petronas, Korea National Oil Corporation, and China National Petroleum Corporation signed a production-sharing agreement to explore and develop oil and gas fields in the Aral Sea, saying, "The Aral Sea is largely unknown, but it holds a lot of promise in terms of finding oil and gas. There is risk, of course, but we believe in the success of this unique project." The consortium was created in September 2005.[88]
+
+As of 1 June 2010, 500,000 cubic meters of gas had been extracted from the region at a depth of 3 km.[89]
+
+The plight of the Aral coast was portrayed in the 1989 film Psy ("Dogs") by Soviet director Dmitri Svetozarov.[90] The film was shot on location in an actual ghost town located near the Aral Sea, showing scenes of abandoned buildings and scattered vessels.
+
+In 2000, the MirrorMundo foundation produced a documentary film called Delta Blues about the problems arising from the drying up of the sea.[91]
+
+In June 2007, BBC World broadcast a documentary called Back From the Brink? made by Borna Alikhani and Guy Creasey, which showed some of the changes in the region since the introduction of the Aklak Dam.
+
+Bakhtyar Khudojnazarov's 2012 movie Waiting for the Sea deals with the impacts on people's life in a fishing town at the shore of the Aral Sea.
+
+In 2012 Christoph Pasour and Alfred Diebold produced an 85-minute film with the title "From the glaciers to the Aral Sea", which shows the water management system in the Aral Sea basin and in particular the situation around the Aral Sea. The film was first screened at the 6th World Water Forum in Marseille, France, in 2012 and is now available on the website: www.waterunites-ca.org[92] and on Alfred Diebold's YouTube channel: waterunitesca.[93]
+
+In October 2013, Al Jazeera produced a documentary film called People of The Lake, directed by Ensar Altay, describing the current situation.[94]
+
+In 2014, director Po Powell shot much of the footage for the Pink Floyd single "Louder than Words" video near the remains of the Aral Sea on the border between Kazakhstan and Uzbekistan.[95]
+
+In October 2018, the BBC produced a programme called Fashion's Dirty Secrets, a large part of which shows the extent of the shrinking Aral and its consequences, together with maybe a little glimmer of hope.[96]

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+The Barents Sea (/ˈbærənts/ BARR-ənts, also US: /ˈbɑːrənts/ BAR-ənts;[1] Norwegian: Barentshavet, Urban East Norwegian: [ˈbɑ̀ːrəntsˌhɑːvə];[2] Russian: Баренцево море, romanized: Barentsevo More) is a marginal sea of the Arctic Ocean,[3] located off the northern coasts of Norway and Russia and divided between Norwegian and Russian territorial waters.[4] Known among Russians in the Middle Ages as the Murman Sea ("Norwegian Sea"), the current name of the sea is after the historical Dutch navigator Willem Barentsz.
+
+This is a rather shallow shelf sea, with an average depth of 230 metres (750 ft), and it is an important site for both fishing and hydrocarbon exploration.[5]  The Barents Sea is bordered by the Kola Peninsula to the south, the shelf edge towards the Norwegian Sea to the west, and the archipelagos of Svalbard to the northwest, Franz Josef Land to the northeast and Novaya Zemlya to the east. The islands of Novaya Zemlya, an extension of the northern end of the Ural Mountains, separate the Barents Sea from the Kara Sea.
+
+Although part of the Arctic Ocean, the Barents Sea has been characterised as "turning into the Atlantic" because of its status as "the Arctic warming hot spot." Hydrologic changes due to global warming have led to a reduction in sea ice and in stratification of the water column, which could produce major changes in weather in Eurasia.[6]
+
+The southern half of the Barents Sea, including the ports of Murmansk (Russia) and Vardø (Norway) remain ice-free year round due to the warm North Atlantic drift.  In September, the entire Barents Sea is more or less completely ice-free.  Until the Winter War (1939–40), Finland's territory also reached to the Barents Sea. Its harbor at Petsamo was Finland's only ice-free winter harbor.
+
+There are three main types of water masses in the Barents Sea: Warm, salty Atlantic water (temperature >3 °C, salinity >35) from the North Atlantic drift; cold Arctic water (temperature <0 °C, salinity <35) from the north; and warm, but not very salty, coastal water (temperature >3 °C, salinity <34.7). Between the Atlantic and Polar waters, a front called the Polar Front is formed.  In the western parts of the sea (close to Bear Island), this front is determined by the bottom topography and is therefore relatively sharp and stable from year to year, while in the east (towards Novaya Zemlya), it can be quite diffuse and its position can vary markedly between years.
+
+The lands of Novaya Zemlya attained most of their early Holocene coastal deglaciation approximately 10,000 years before present.[7]
+
+The International Hydrographic Organization defines the limits of the "Barentsz Sea"  [sic] as follows:[8]
+
+Other islands in the Barents Sea include Chaichy and Timanets.
+
+The Barents Sea was originally formed from two major continental collisions: the Caledonian orogeny, in which the Baltica and Laurentia collided to form Laurasia, and a subsequent collision between Laurasia and Western Siberia.  Most of its geological history is dominated by extensional tectonics, caused by the collapse of the Caledonian and Uralian orogenic belts and the break-up of Pangaea.[9] These events created the major rift basins that dominate the Barents Shelf, along with various platforms and structural highs.  The later geological history of the Barents Sea is dominated by Late Cenozoic uplift, particularly that caused by Quaternary glaciation, which has resulted in erosion and deposition of significant sediment.[10]
+
+Due to the North Atlantic drift, the Barents Sea has a high biological production compared to other oceans of similar latitude.  The spring bloom of phytoplankton can start quite early near the ice edge, because the fresh water from the melting ice makes up a stable water layer on top of the sea water. The phytoplankton bloom feeds zooplankton such as Calanus finmarchicus, Calanus glacialis, Calanus hyperboreus, Oithona spp., and krill. The zooplankton feeders include young cod, capelin, polar cod, whales, and little auk. The capelin is a key food for top predators such as the north-east Arctic cod, harp seals, and seabirds such as common guillemot and Brunnich's guillemot.  The fisheries of the Barents Sea, in particular the cod fisheries, are of great importance for both Norway and Russia.
+
+SIZEX-89 was an international winter experiment in 1989 for which the main objectives were to perform sensor signature studies of different ice types in order to develop SAR algorithms for ice variables, such as ice types, ice concentrations and ice kinematics.[11]
+Although previous research suggested that predation by whales may be the cause of depleting fish stocks, more recent research suggests that marine mammal consumption has only a trivial influence on fisheries. A model assessing the effects of fisheries and climate was far more accurate at describing trends in fish abundance.[12] There is a genetically distinct polar bear population associated with the Barents Sea.[13]
+
+The Barents Sea was formerly known to Russians as Murmanskoye More, or the "Sea of Murmans" (i.e., their term for Norwegians). It appears with this name in sixteenth-century maps, including Gerard Mercator's Map of the Arctic published in his 1595 atlas. Its eastern corner, in the region of the Pechora River's estuary, has been known as Pechorskoye Morye, that is, Pechora Sea.
+
+This sea was given its present name by Europeans in honor of Willem Barentsz, a Dutch navigator and explorer. Barentsz was the leader of early expeditions to the far north, at the end of the sixteenth century.
+
+The Barents Sea has been called by sailors "The Devil's Dance Floor" due to its unpredictability and difficulty level.[14]
+
+Ocean rowers call it "Devil's Jaw". In 2017, after the first recorded complete man-powered crossing of the Barents Sea from Tromsø to Longyearbyen in a row boat by Polar Row expedition, captain Fiann Paul was asked by Norwegian TV2 how a rower would name the Barents Sea. Fiann responded that he would name it "Devil's Jaw", adding that the winds you constantly battle are like breath from the devil's nostrils while he holds you in his jaws.[15]
+
+Seabed mapping was completed in 1933; the first full map was produced by Russian marine geologist Maria Klenova.
+
+The Barents Sea was the site of a notable World War II engagement, a German surface raiding attack on a British merchant convoy, which later became known as the Battle of the Barents Sea. Under the command of Oskar Kummetz, the German warships sank minelayer HMS Bramble and destroyer HMS Achates, but lost destroyer Z16 Friedrich Eckoldt, and Admiral Hipper was severely damaged by British gunfire. The Germans later retreated and the British convoy arrived safely at Murmansk shortly afterwards.
+
+During the Cold War, the Soviet Red Banner Northern Fleet used the southern reaches of the sea as a ballistic missile submarine bastion, a strategy that Russia continues. Nuclear contamination from dumped Russian naval reactors is an environmental concern in the Barents Sea.
+
+For decades there was a boundary dispute between Norway and Russia regarding the position of the boundary between their respective claims to the Barents Sea.  The Norwegians favoured a median line, based on the Geneva Convention of 1958, whereas the Russians favoured a meridian- based sector line, based on a Soviet decision of 1926.[9]  A neutral "grey" zone between the competing claims had an area of 175,000 sq.km, which is approximately 12% of the total area of the Barents Sea.  The two countries started negotiations on the location of the boundary in 1974, and agreed to a moratorium on hydrocarbon exploration in 1976.
+
+Twenty years after the fall of the Soviet Union, in 2010 Norway and Russia signed an agreement that placed the boundary equidistant from their competing claims. This was ratified and went into force on 7 July 2011, opening the grey zone for hydrocarbon exploration.[16]
+
+Encouraged by the success of oil exploration and production in the North Sea in the 1960s, Norway began hydrocarbon exploration in the Barents Sea in 1969.  They acquired seismic reflection surveys through the following years, which were analysed to understand the location of the main sedimentary basins.[9] NorskHydro drilled the first well in 1980, which was a dry hole, and the first discoveries were made the following year: the Alke and Askeladden gas fields.[9]  Several more discoveries were made on the Norwegian side of the Barents Sea throughout the 1980s, including the important Snøhvit field.[17]
+
+But, interest in the area began to wane due to a succession of dry holes, wells containing only gas (which was cheap at the time), and the prohibitive costs of developing wells in such a remote area.  Interest in the area was reignited in the late 2000s, after the Snovhit field was finally brought into production[18] and two new large discoveries were made.[19]
+
+The Russians began exploration in their territory around the same time, encouraged by their success in the Timan-Pechora Basin.[9]  They drilled their first wells in the early 1980s, and some very large gas fields were discovered throughout this decade.  The Shtokman field was discovered in 1988 and is classed as a giant gas field: currently the 5th-largest gas field in the world.  Similar practical difficulties Barents Sea resulted in a decline in Russian exploration, aggravated by the nation's political instability of the 1990s.
+
+The Barents Sea contains the world's largest remaining cod population,[20] as well as important stocks of haddock and capelin.  Fishing is managed jointly by Russia and Norway in the form of the Joint Norwegian–Russian Fisheries Commission, established in 1976, in an attempt to keep track of how many fish are leaving the ecosystem due to fishing.[21]  The Joint Norwegian-Russian Fisheries Commission sets Total Allowable Catches (TACs) for multiple species throughout their migratory tracks.  Through the Commission, Norway and Russia also exchange fishing quotas and catch statistics to ensure the TACs are not being violated.
+
+But there are problems with reporting under this system, and researchers believe that they do not have accurate data for the effects of fishing on the Barents Sea ecosystem. Cod is one of the major catches. A large portion of catches are not reported when the fishing boats land, in order to account for profits that are being lost to high taxes and fees.  Since many fishermen do not strictly follow the TACs and rules set forth by the Commission, the amount of fish being extracted annually from the Barents Sea is underestimated.
+
+The Barents Sea, where temperate waters from the Gulf Stream and cold waters from the Arctic meet, is home to an enormous diversity of organisms, which are well adapted to the extreme conditions of their marine habitats. This makes these arctic species very attractive for marine bioprospecting. Marine bioprospecting may be defined as the search for bioactive molecules and compounds from marine sources having new, unique properties and the potential for commercial applications. Amongst others, applications include medicines, food and feed, textiles, cosmetics and the process industry.
+
+The Norwegian government strategically supports the development of marine bioprospecting as it has the potential to contribute to new and sustainable wealth creation. Tromsø and the northern areas of Norway play a central role in this strategy. They have excellent access to unique Arctic marine organisms, existing marine industries, and R&D competence and infrastructure in this region. Since 2007, science and industry have cooperated closely on bioprospecting, and the development and commercialization of new products.[22]
+
+MabCent-SFI is one of fourteen Research-Based Innovation Centers initiated by the Research Council of Norway. It is the only one within the field of “bioactive compounds and drug discovery” that is based on bioactives from marine organisms. MabCent-SFI maintains a focus on bioactives from Arctic and sub-Arctic organisms. By the end of 2011, MabCent had tested about 200,000 extracts, finding several hundred "hits".  Through further research and development, some of these hits will become valuable "leads", i.e. characterized compounds known to possess biological effects of interest.
+
+The commercial partners in MabCent-SFI are Biotec Pharmacon ASA and its subsidiary ArcticZymes AS, ABC BioScience AS, Lytix Biopharma AS and Pronova BioPharma ASA.  ArcticZymes is also a partner in MARZymes, a project financed by the Research Council of Norway to find marine enzymes which are adapted to the extreme conditions in the Arctic. The science partners in MabCent-SFI are Marbank, a national marine biobank located in Tromsø; Marbio, a medium/high-throughput platform for screening and identification of bioactive compounds; and Norstruct, a protein structure determination platform. Mabcent-SFI is hosted by the University of Tromsø.
+
+BioTech North is an emerging biotechnology cluster of enterprises and R&D organizations, which cooperate closely with regional funding and development actors (triple helix). As bioactive molecules and compounds from Arctic marine resources form the basis of activities for the majority of the cluster members, BioTech North serves as a marine biotech cluster. The majority of BioTech North’s enterprises are active within life science applications and markets. To date the cluster contains around thirty organizations from both the private and public sector. It has received Arena status and is funded through the [ Arena] programme financed by Innovation Norway, SIVA and The Research Council of Norway. Stakeholders of BioTech North include Barents BioCentre Lab, BioStruct, Marbank, Norut, Nofima, Mabcent-SFI, University of Tromsø, Unilab, Barentzymes AS, Trofi, Scandiderma AS, Prophylix Pharma AS, Olivita, Marealis, ProCelo, Probio, Lytix Biopharma, Integorgen, d'Liver, Genøk, Cognis, Clare AS, Chitinor, Calanus AS, Biotec Betaglucans, Ayanda, ArcticZymes AS, ABC Bioscience, Akvaplanniva.
+

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+An army (from Latin arma "arms, weapons" via Old French armée, "armed" [feminine]), ground force or land force is a fighting force that fights primarily on land. In the broadest sense, it is the land-based military branch, service branch or armed service of a nation or state. It may also include aviation assets by possessing an army aviation component. Within a national military force, the word army may also mean a field army.
+
+In some countries, such as France and China, the term "army", especially in its plural form "armies", has the broader meaning of armed forces as a whole, while retaining the colloquial sense of land forces. To differentiate the colloquial army from the formal concept of military force, the term is qualified, for example in France the land force is called Armée de terre, meaning Land Army, and the air force is called Armée de l'Air, meaning Air Army. The naval force, although not using the term "army", is also included in the broad sense of the term "armies" — thus the French Navy is an integral component of the collective French Armies (French Armed Forces) under the Ministry of the Armies. A similar pattern is seen in China, with the People's Liberation Army (PLA) being the overall military, the "actual army" being the PLA Ground Force, and so forth for the PLA Air Force, the PLA Navy, and other branches.
+
+The current largest army in the world, by number of active troops, is the PLA Ground Force of China with 1,600,000 active troops and 510,000 reserve personnel followed by the Indian Army with 1,237,117 active troops and 960,000 reserve personnel.
+
+By convention, irregular military is understood in contrast to regular armies which grew slowly from personal bodyguards or elite militia. Regular in this case refers to standardized doctrines, uniforms, organizations, etc. Regular military can also refer to full-time status (standing army), versus reserve or part-time personnel. Other distinctions may separate statutory forces (established under laws such as the National Defence Act), from de facto "non-statutory" forces such as some guerrilla and revolutionary armies. Armies may also be expeditionary (designed for overseas or international deployment) or fencible (designed for – or restricted to – homeland defence)
+
+India's armies were among the first in the world. The first recorded battle, the Battle of the Ten Kings, happened when a Hindu Aryan king named Sudas defeated an alliance of ten kings and their supportive chieftains. During the Iron Age, the Maurya and Nanda Empires had the largest armies in the world, the peak being approximately over 600,000 Infantry, 30,000 Cavalry, 8,000 War-Chariots and 9,000 War Elephants not including tributary state allies.[1][2][3][4] In the Gupta age, large armies of longbowmen were recruited to fight off invading horse archer armies. Elephants, pikemen and cavalry were other featured troops.
+
+In Rajput times, the main piece of equipment was iron or chain-mail armour, a round shield, either a curved blade or a straight-sword, a chakra disc and a katar dagger.[citation needed]
+
+The states of China raised armies for at least 1000 years before the Spring and Autumn Annals[citation needed]. By the Warring States period, the crossbow had been perfected enough to become a military secret, with bronze bolts which could pierce any armor. Thus any political power of a state rested on the armies and their organization. China underwent political consolidation of the states of Han (韓), Wei (魏), Chu (楚), Yan (燕), Zhao (趙) and Qi (齊), until by 221 BCE, Qin Shi Huang (秦始皇帝), the first emperor of the Qin dynasty, attained absolute power. This first emperor of China could command the creation of a Terracotta Army to guard his tomb in the city of Xi'an (西安), as well as a realignment of the Great Wall of China to strengthen his empire against insurrection, invasion and incursion.
+
+Sun Tzu's The Art of War remains one of China's Seven Military Classics, even though it is two thousand years old.[5] Since no political figure could exist without an army, measures were taken to ensure only the most capable leaders could control the armies.[6] Civil bureaucracies (士大夫) arose to control the productive power of the states, and their military power.[7]
+
+The Spartan Army was one of the earliest known professional armies. Boys were sent to a barracks at the age of seven or eight to train for becoming a soldier. At the age of thirty they were released from the barracks and allowed to marry and have a family. After that, men devoted their lives to war until their retirement at the age of 60. Unlike other civilizations, whose armies had to disband during the planting and harvest seasons, the Spartan serfs or helots, did the manual labor.
+
+This allowed the Spartans to field a full-time army with a campaign season that lasted all year.[citation needed] The Spartan Army was largely composed of hoplites, equipped with arms and armor nearly identical to each other. Each hoplite bore the Spartan emblem and a scarlet uniform. The main pieces of this armor were a round shield, a spear and a helmet.
+
+The Roman Army had its origins in the citizen army of the Republic, which was staffed by citizens serving mandatory duty for Rome. Reforms turned the army into a professional organization which was still largely filled by citizens, but these citizens served continuously for 25 years before being discharged.[8]
+
+The Romans were also noted for making use of auxiliary troops, non-Romans who served with the legions and filled roles that the traditional Roman military could not fill effectively, such as light skirmish troops and heavy cavalry. After their service in the army they were made citizens of Rome and then their children were citizens also. They were also given land and money to settle in Rome. In the Late Roman Empire, these auxiliary troops, along with foreign mercenaries, became the core of the Roman Army; moreover, by the time of the Late Roman Empire tribes such as the Visigoths were paid to serve as mercenaries.
+
+In the earliest Middle Ages it was the obligation of every aristocrat to respond to the call to battle with his own equipment, archers, and infantry. This decentralized system was necessary due to the social order of the time, but could lead to motley forces with variable training, equipment and abilities. The more resources the noble had access to, the better his troops would be.
+
+Initially, the words "knight" and "noble" were used interchangeably as there was not generally a distinction between them. While the nobility did fight upon horseback, they were also supported by lower class citizens – and mercenaries and criminals – whose only purpose was participating in warfare because, most often than not, they held brief employment during their lord's engagement.[9] As the Middle Ages progressed and feudalism developed in a legitimate social and economic system, knights started to develop into their own class with a minor caveat: they were still in debt to their lord. No longer primarily driven by economic need, the newly established vassal class were, instead, driven by fealty and chivalry.
+
+As central governments grew in power, a return to the citizen armies of the classical period also began, as central levies of the peasantry began to be the central recruiting tool. England was one of the most centralized states in the Middle Ages, and the armies that fought in the Hundred Years' War were, predominantly, composed of paid professionals.
+
+In theory, every Englishman had an obligation to serve for forty days. Forty days was not long enough for a campaign, especially one on the continent.[10]
+
+Thus the scutage was introduced, whereby most Englishmen paid to escape their service and this money was used to create a permanent army. However, almost all high medieval armies in Europe were composed of a great deal of paid core troops, and there was a large mercenary market in Europe from at least the early 12th century.
+
+As the Middle Ages progressed in Italy, Italian cities began to rely mostly on mercenaries to do their fighting rather than the militias that had dominated the early and high medieval period in this region. These would be groups of career soldiers who would be paid a set rate. Mercenaries tended to be effective soldiers, especially in combination with standing forces, but in Italy they came to dominate the armies of the city states. This made them considerably less reliable than a standing army. Mercenary-on-mercenary warfare in Italy also led to relatively bloodless campaigns which relied as much on maneuver as on battles.
+
+In 1439 the French legislature, known as the  Estates General (French: états généraux), passed laws that restricted military recruitment and training to the king alone. There was a new tax to be raised known as the taille that was to provide funding for a new Royal army. The mercenary companies were given a choice of either joining the Royal army as compagnies d'ordonnance on a permanent basis, or being hunted down and destroyed if they refused. France gained a total standing army of around 6,000 men, which was sent out to gradually eliminate the remaining mercenaries who insisted on operating on their own. The new standing army had a more disciplined and professional approach to warfare than its predecessors. The reforms of the 1440s,  eventually led to the French victory at Castillon in 1453, and the conclusion of the Hundred Years' War. By 1450 the companies were divided into the field army, known as the grande ordonnance and the garrison force known as the petite ordonnance.[11]
+
+First nation states lacked the funds needed to maintain standing forces, so they tended to hire mercenaries to serve in their armies during wartime. Such mercenaries typically formed at the ends of periods of conflict, when men-at-arms were no longer needed by their respective governments.
+
+The veteran soldiers thus looked for other forms of employment, often becoming mercenaries. Free Companies would often specialize in forms of combat that required longer periods of training that was not available in the form of a mobilized militia.
+
+As late as the 1650s, most troops were mercenaries. However, after the 17th century, most states invested in better disciplined and more politically reliable permanent troops. For a time mercenaries became important as trainers and administrators, but soon these tasks were also taken by the state. The massive size of these armies required a large supporting force of administrators.
+
+The newly centralized states were forced to set up vast organized bureaucracies to manage these armies, which some historians argue is the basis of the modern bureaucratic state. The combination of increased taxes and increased centralisation of government functions caused a series of revolts across Europe such as the Fronde in France and the English Civil War.
+
+In many countries, the resolution of this conflict was the rise of absolute monarchy. Only in England and the Netherlands did representative government evolve as an alternative. From the late 17th century, states learned how to finance wars through long term low interest loans from national banking institutions. The first state to master this process was the Dutch Republic. This transformation in the armies of Europe had great social impact. The defense of the state now rested on the commoners, not on the aristocrats.
+
+However, aristocrats continued to monopolise the officer corps of almost all early modern armies, including their high command. Moreover, popular revolts almost always failed unless they had the support and patronage of the noble or gentry classes. The new armies, because of their vast expense, were also dependent on taxation and the commercial classes who also began to demand a greater role in society. The great commercial powers of the Dutch and English matched much larger states in military might.
+
+As any man could be quickly trained in the use of a musket, it became far easier to form massive armies. The inaccuracy of the weapons necessitated large groups of massed soldiers. This led to a rapid swelling of the size of armies. For the first time huge masses of the population could enter combat, rather than just the highly skilled professionals.
+
+It has been argued that the drawing of men from across the nation into an organized corps helped breed national unity and patriotism, and during this period the modern notion of the nation state was born. However, this would only become apparent after the French Revolutionary Wars. At this time, the levée en masse and conscription would become the defining paradigm of modern warfare.
+
+Before then, however, most national armies were in fact composed of many nationalities. In Spain armies were recruited from all the Spanish European territories including Spain, Italy, Wallonia (Walloon Guards) and Germany. The French recruited some soldiers from Germany, Switzerland as well as from Piedmont. Britain recruited Hessian and Hanovrian troops until the late 18th century. Irish Catholics made careers for themselves in the armies of many Catholic European states.
+
+Prior to the English Civil War in England, the monarch maintained a personal bodyguard of Yeomen of the Guard and the Honourable Corps of Gentlemen at Arms, or "gentlemen pensioners", and a few locally raised companies to garrison important places such as Berwick on Tweed or Portsmouth (or Calais before it was recaptured by France in 1558).
+
+Troops for foreign expeditions were raised upon an ad hoc basis. Noblemen and professional regular soldiers were commissioned by the monarch to supply troops, raising their quotas by indenture from a variety of sources. On January 26, 1661 Charles II issued the Royal Warrant that created the genesis of what would become the British Army, although the Scottish and English Armies would remain two separate organizations until the unification of England and Scotland in 1707. The small force was represented by only a few regiments.
+
+After the American Revolutionary War the Continental Army was quickly disbanded as part of the Americans' distrust of standing armies, and irregular state militias became the sole ground army of the United States, with the exception of one battery of artillery guarding West Point's arsenal. Then First American Regiment was established in 1784. However, because of continuing conflict with Native Americans, it was soon realized that it was necessary to field a trained standing army. The first of these, the Legion of the United States, was established in 1791.
+
+Until 1733 the common soldiers of Prussian Army consisted largely of peasantry recruited or impressed from Brandenburg–Prussia, leading many to flee to neighboring countries.[13] To halt this trend, Frederick William I divided Prussia into regimental cantons. Every youth was required to serve as a soldier in these recruitment districts for three months each year; this met agrarian needs and added extra troops to bolster the regular ranks.[14]
+
+Russian tsars before Peter I of Russia maintained professional hereditary musketeer corps (streltsy in Russian) that were highly unreliable and undisciplined. In times of war the armed forces were augmented by peasants. Peter I introduced a modern regular army built on German model, but with a new aspect: officers not necessarily from nobility, as talented commoners were given promotions that eventually included a noble title at the attainment of an officer's rank. Conscription of peasants and townspeople was based on quota system, per settlement. Initially it was based on the number of households, later it was based on the population numbers.[16] The term of service in the 18th century was for life. In 1793 it was reduced to 25 years. In 1834 it was reduced to 20 years plus 5 years in reserve and in 1855 to 12 years plus 3 years of reserve.[16][chronology citation needed]
+
+The first Ottoman standing army were Janissaries. They replaced forces that mostly comprised tribal warriors (ghazis) whose loyalty and morale could not always be trusted. The first Janissary units were formed from prisoners of war and slaves, probably as a result of the sultan taking his traditional one-fifth share of his army's booty in kind rather than cash.
+
+From the 1380s onwards, their ranks were filled under the devşirme system, where feudal dues were paid by service to the sultan. The "recruits" were mostly Christian youths, reminiscent of mamluks.
+
+China organized the Manchu people into the Eight Banner system in the early 17th century. Defected Ming armies formed the Green Standard Army. These troops enlisted voluntarily and for long terms of service.
+
+Conscription allowed the French Republic to form the Grande Armée, what Napoleon Bonaparte called "the nation in arms", which successfully battled European professional armies.
+
+Conscription, particularly when the conscripts are being sent to foreign wars that do not directly affect the security of the nation, has historically been highly politically contentious in democracies.
+
+Canada also had a political dispute over conscription during World War II. Similarly, mass protests against conscription to fight the Vietnam War occurred in several countries in the late 1960s.
+
+In developed nations, the increasing emphasis on technological firepower and better-trained fighting forces, the sheer unlikelihood of a conventional military assault on most developed nations, as well as memories of the contentiousness of the Vietnam War experience, make mass conscription unlikely in the foreseeable future.
+
+Russia, as well as many other nations, retains mainly a conscript army. There is also a very rare citizen army as used in Switzerland (see Military of Switzerland).
+
+Western armies are usually subdivided as follows:
+
+A field army is composed of a headquarters, army troops, a variable number of corps, typically between three and four, and a variable number of divisions, also between three and four. A battle is influenced at the Field Army level by transferring divisions and reinforcements from one corps to another to increase the pressure on the enemy at a critical point. Field armies are controlled by a general or lieutenant general.
+
+A particular army can be named or numbered to distinguish it from military land forces in general. For example, the First United States Army and the Army of Northern Virginia. In the British Army it is normal to spell out the ordinal number of an army (e.g. First Army), whereas lower formations use figures (e.g. 1st Division).
+
+Armies (as well as army groups and theaters) are large formations which vary significantly between armed forces in size, composition, and scope of responsibility.
+
+In the Soviet Red Army and the Soviet Air Force, "Armies" could vary in size, but were subordinate to an Army Group-sized "front" in wartime. In peacetime, a Soviet army was usually subordinate to a military district. Viktor Suvorov's Inside the Soviet Army describes how Cold War era Soviet military districts were actually composed of a front headquarters and a military district headquarters co-located for administration and deception ('maskirovika') reasons.

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+The Caribbean Sea (Spanish: Mar Caribe; French: Mer des Caraïbes; Haitian Creole: Lamè Karayib; Jamaican Patois: Kiaribiyan Sii; Dutch: Caraïbische Zee; Papiamento: Laman Karibe) is an American mediterranean sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico and Central America to the west and south west, to the north by the Greater Antilles starting with Cuba, to the east by the Lesser Antilles, and to the south by the north coast of South America.
+
+The entire area of the Caribbean Sea, the numerous islands of the West Indies, and adjacent coasts, are collectively known as the Caribbean. The Caribbean Sea is one of the largest seas and has an area of about 2,754,000 km2 (1,063,000 sq mi).[1][2] The sea's deepest point is the Cayman Trough, between the Cayman Islands and Jamaica, at 7,686 m (25,217 ft) below sea level. The Caribbean coastline has many gulfs and bays: the Gulf of Gonâve, Gulf of Venezuela, Gulf of Darién, Golfo de los Mosquitos, Gulf of Paria and Gulf of Honduras.
+
+The Caribbean Sea has the world's second largest barrier reef, the Mesoamerican Barrier Reef. It runs 1,000 km (620 mi) along the coasts of Mexico, Belize, Guatemala, and Honduras.[3]
+
+The name "Caribbean" derives from the Caribs, one of the region's dominant Native American groups at the time of European contact during the late 15th century. After Christopher Columbus landed in the Bahamas in 1492, the Spanish term Antillas applied to the lands; stemming from this, "Sea of the Antilles" became a common alternative name for "Caribbean Sea" in various European languages. During the first century of development, Spanish dominance in the region remained undisputed.
+
+From the 16th century, Europeans visiting the Caribbean region identified the "South Sea" (the Pacific Ocean, to the south of the isthmus of Panama) as opposed to the "North Sea" (the Caribbean Sea, to the north of the same isthmus).[4]
+
+The Caribbean Sea had been unknown to the populations of Eurasia until 1492, when Christopher Columbus sailed into Caribbean waters on a quest to find a sea route to Asia. At that time the Western Hemisphere in general was unknown to most Europeans, although it had been discovered between the years 800 and 1000 by the vikings. Following the discovery of the islands by Columbus, the area was quickly colonized by several Western cultures (initially Spain, then later England, the Dutch Republic, France, Courland and Denmark). Following the colonization of the Caribbean islands, the Caribbean Sea became a busy area for European-based marine trading and transports, and this commerce eventually attracted pirates such as Samuel Bellamy and Blackbeard.
+
+As of 2015[update] the area is home to 22 island territories and borders 12 continental countries.
+
+The International Hydrographic Organization defines the limits of the Caribbean Sea as follows:[5]
+
+Note that, although Barbados is an island on the same continental shelf, it is considered to be in the Atlantic Ocean rather than the Caribbean Sea.
+
+The Caribbean Sea is an oceanic sea largely situated on the Caribbean Plate. The Caribbean Sea is separated from the ocean by several island arcs of various ages. The youngest stretches from the Lesser Antilles to the Virgin Islands to the north east of Trinidad and Tobago off the coast of Venezuela. This arc was formed by the collision of the South American Plate with the Caribbean Plate and includes active and extinct volcanoes such as Mount Pelee, the Quill (volcano) on Sint Eustatius in the Caribbean Netherlands and Morne Trois Pitons on Dominica. The larger islands in the northern part of the sea Cuba, Hispaniola, Jamaica and Puerto Rico lie on an older island arc.
+
+The geological age of the Caribbean Sea is estimated to be between 160 and 180 million years and was formed by a horizontal fracture that split the supercontinent called Pangea in the Mesozoic Era.[8] It is assumed the proto-caribbean basin existed in the Devonian period. In the early Carboniferous movement of Gondwana to the north and its convergence with the Euramerica basin decreased in size. The next stage of the Caribbean Sea's formation began in the Triassic. Powerful rifting led to the formation of narrow troughs, stretching from modern Newfoundland to the west coast of the Gulf of Mexico which formed siliciclastic sedimentary rocks. In the early Jurassic due to powerful marine transgression, water broke into the present area of the Gulf of Mexico creating a vast shallow pool. The emergence of deep basins in the Caribbean occurred during the Middle Jurassic rifting. The emergence of these basins marked the beginning of the Atlantic Ocean and contributed to the destruction of Pangaea at the end of the late Jurassic. During the Cretaceous the Caribbean acquired the shape close to that seen today. In the early Paleogene due to Marine regression the Caribbean became separated from the Gulf of Mexico and the Atlantic Ocean by the land of Cuba and Haiti. The Caribbean remained like this for most of the Cenozoic until the Holocene when rising water levels of the oceans restored communication with the Atlantic Ocean.
+
+The Caribbean's floor is composed of sub-oceanic sediments of deep red clay in the deep basins and troughs. On continental slopes and ridges calcareous silts are found. Clay minerals likely having been deposited by the mainland river Orinoco and the Magdalena River. Deposits on the bottom of the Caribbean Sea and Gulf of Mexico have a thickness of about 1 km (0.62 mi). Upper sedimentary layers relate to the period from the Mesozoic to the Cenozoic (250 million years ago to present) and the lower layers from the Paleozoic to the Mesozoic.
+
+The Caribbean sea floor is divided into five basins separated from each other by underwater ridges and mountain ranges. Atlantic Ocean water enters the Caribbean through the Anegada Passage lying between the Lesser Antilles and Virgin Islands and the Windward Passage located between Cuba and Haiti. The Yucatán Channel between Mexico and Cuba links the Gulf of Mexico with the Caribbean. The deepest points of the sea lie in Cayman Trough with depths reaching approximately 7,686 m (25,220 ft). Despite this, the Caribbean Sea is considered a relatively shallow sea in comparison to other bodies of water.
+The pressure of the South American Plate to the east of the Caribbean causes the region of the Lesser Antilles to have high volcanic activity. There was a very serious eruption of Mount Pelée in 1902 which caused many casualties.
+
+The Caribbean sea floor is also home to two oceanic trenches: the Cayman Trench and Puerto Rico Trench, which put the area at a high risk of earthquakes. Underwater earthquakes pose a threat of generating tsunamis which could have a devastating effect on the Caribbean islands. Scientific data reveals that over the last 500 years the area has seen a dozen earthquakes above 7.5 magnitude.[9] Most recently, a 7.1 earthquake struck Haiti on January 12, 2010.
+
+The hydrology of the sea has a high level of homogeneity. Annual variations in monthly average water temperatures at the surface do not exceed 3 °C (5.4 °F). Over the past fifty years the Caribbean has gone through three stages: cooling until 1974; a cold phase with peaks during 1974–1976 and 1984–1986 then; a warming phase with an increase in temperature of 0.6 °C (1.1 °F) per year. Virtually all temperature extremes were associated with the phenomena of El Niño and La Niña. The salinity of seawater is about 3.6% and its density is 1,023.5–1,024.0 kg/m3 (63.90–63.93 lb/cu ft). The surface water colour is blue-green to green.
+
+The Caribbean's depth in its wider basins and deep water temperatures are similar to those of the Atlantic. Atlantic deep water is thought to spill into the Caribbean and contribute to the general deep water of its sea.[10] The surface water (30 m; 100 feet) acts as an extension of the northern Atlantic as the Guiana Current and part of the North Equatorial Current enter the sea on the east. On the western side of the sea the trade winds influence a northerly current which causes an upwelling and a rich fishery near Yucatán.[11]
+
+The Caribbean is home to about 9% of the world's coral reefs covering about 50,000 km2 (19,000 sq mi), most of which are located off the Caribbean Islands and the Central American coast.[12] Among them stands out the Belize Barrier Reef with an area of 963 km2 (372 sq mi) which was declared a World Heritage Site in 1996. It forms part of the Great Mayan Reef also known as the MBRS and being over 1,000 km (600 mi) in length is the world's second longest. It runs along the Caribbean coasts of Mexico, Belize, Guatemala and Honduras.
+
+During the past ten years,[when?] unusually warm Caribbean waters have been increasingly threatening Caribbean coral reefs. Coral reefs support some of the most diverse marine habitats in the world, but they are fragile ecosystems. When tropical waters become unusually warm for extended periods of time, microscopic plants called zooxanthellae, which are symbiotic partners living within the coral polyp tissues, die off. These plants provide food for the corals, and give them their color. The result of the death and dispersal of these tiny plants is called coral bleaching, and can lead to the devastation of large areas of reef. Over 42% of corals are completely bleached and 95% are experiencing some type of whitening.[13] Historically the Caribbean is thought to contain 14% of the world's coral reefs.[14]
+
+The habitats supported by the reefs are critical to such tourist activities as fishing and diving, and provide an annual economic value to Caribbean nations of US$3.1–4.6 billion. Continued destruction of the reefs could severely damage the region's economy.[15] A Protocol of the Convention for the Protection and Development of the Marine Environment of the Wider Caribbean Region came in effect in 1986 to protect the various endangered marine life of the Caribbean through forbidding human activities that would advance the continued destruction of such marine life in various areas. Currently this protocol has been ratified by 15 countries.[16] Also, several charitable organisations have been formed to preserve the Caribbean marine life, such as Caribbean Conservation Corporation which seeks to study and protect sea turtles while educating others about them.[17]
+
+In connection with the foregoing, the Institute of Marine Sciences and Limnology of the National Autonomous University of Mexico, conducted a regional study, funded by the Department of Technical Cooperation of the International Atomic Energy Agency, in which specialists from 11 Latin American countries (Colombia, Costa Rica, Cuba, Guatemala, Haiti, Honduras, Mexico, Nicaragua, Panama, Dominican Republic, Venezuela plus Jamaica) participated. The findings indicate that heavy metals such as mercury, arsenic, and lead, have been identified in the coastal zone of the Caribbean Sea. Analysis of toxic metals and hydrocarbons is based on the investigation of coastal sediments that have accumulated less than 50 meters deep during the last hundred and fifty years. The project results were presented in Vienna in the forum "Water Matters", and the 2011 General Conference of said multilateral organization.[18]
+
+The climate of the Caribbean is driven by the low latitude and tropical ocean currents that run through it. The principal ocean current is the North Equatorial Current, which enters the region from the tropical Atlantic. The climate of the area is tropical, varying from tropical rainforest in some areas to tropical savanna in others. There are also some locations that are arid climates with considerable drought in some years.
+
+Rainfall varies with elevation, size and water currents (cool upwelling keep the ABC islands arid). Warm, moist trade winds blow consistently from the east, creating both rain forest and semi arid climates across the region. The tropical rainforest climates include lowland areas near the Caribbean Sea from Costa Rica north to Belize, as well as the Dominican Republic and Puerto Rico, while the more seasonal dry tropical savanna climates are found in Cuba, northern Venezuela, and southern Yucatán, Mexico. Arid climates are found along the extreme southern coast of Venezuela out to the islands including Aruba and Curaçao, as well as the northern tip of Yucatán[20]
+
+Tropical cyclones are a threat to the nations that rim the Caribbean Sea. While landfalls are infrequent, the resulting loss of life and property damage makes them significant hazard to life in the Caribbean. Tropical cyclones that impact the Caribbean often develop off the West coast of Africa and make their way west across the Atlantic Ocean toward the Caribbean, while other storms develop in the Caribbean itself. The Caribbean hurricane season as a whole lasts from June through November, with the majority of hurricanes occurring during August and September. On average around 9 tropical storms form each year, with 5 reaching hurricane strength. According to the National Hurricane Center 385 hurricanes occurred in the Caribbean between 1494 and 1900.
+
+The region has a high level of biodiversity and many species are endemic to the Caribbean.
+
+The vegetation of the region is mostly tropical but differences in topography, soil and climatic conditions increase species diversity. Where there are porous limestone terraced islands these are generally poor in nutrients. It is estimated that 13,000 species of plants grow in the Caribbean of which 6,500 are endemic. For example, guaiac wood (Guaiacum officinale), the flower of which is the national flower of Jamaica and the Bayahibe rose (Pereskia quisqueyana) which is the national flower of the Dominican Republic and the ceiba which is the national tree of both Puerto Rico and Guatemala. The mahogany is the national tree of the Dominican Republic and Belize. The caimito (Chrysophyllum cainito) grows throughout the Caribbean. In coastal zones there are coconut palms and in lagoons and estuaries are found thick areas of black mangrove and red mangrove (Rhizophora mangle).
+
+In shallow water flora and fauna is concentrated around coral reefs where there is little variation in water temperature, purity and salinity. Leeward side of lagoons provide areas of growth for sea grasses. Turtle grass (Thalassia testudinum) is common in the Caribbean as is manatee grass (Syringodium filiforme) which can grow together as well as in fields of single species at depths up to 20 m (66 ft). Another type shoal grass (Halodule wrightii) grows on sand and mud surfaces at depths of up to 5 m (16 ft). In brackish water of harbours and estuaries at depths less than 2.5 m (8 ft 2 in) widgeongrass (Ruppia maritima) grows. Representatives of three species belonging to the genus Halophila, (Halophila baillonii, Halophila engelmannii and Halophila decipiens) are found at depths of up to 30 m (98 ft) except for Halophila engelmani which does not grow below 5 m (16 ft) and is confined to the Bahamas, Florida, the Greater Antilles and the western part of the Caribbean. Halophila baillonii has been found only in the Lesser Antilles.[21]
+
+Marine biota in the region have representatives of both the Indian and Pacific oceans which were caught in the Caribbean before the emergence of the Isthmus of Panama four million years ago.[22] In the Caribbean Sea there are around 1,000 documented species of fish, including sharks (bull shark, tiger shark, silky shark and Caribbean reef shark), flying fish, giant oceanic manta ray, angel fish, spotfin butterflyfish, parrotfish, Atlantic Goliath grouper, tarpon and moray eels. Throughout the Caribbean there is industrial catching of lobster and sardines (off the coast of Yucatán Peninsula).
+
+There are 90 species of mammals in the Caribbean including sperm whales, humpback whales and dolphins. The island of Jamaica is home to seals and manatees. The Caribbean monk seal which lived in the Caribbean is considered extinct. The solenodon is endangered.
+
+There are 500 species of reptiles (94% of which are endemic). Islands are inhabited by some endemic species such as rock iguanas and American crocodile. The blue iguana, endemic to the island of Grand Cayman, is endangered. The green iguana is invasive to Grand Cayman.  The Mona ground iguana which inhabits the island of Mona, Puerto Rico, is endangered. The rhinoceros iguana from the island of Hispaniola which is shared between Haiti and the Dominican Republic is also endangered. The region has several types of sea turtle (loggerhead, green turtle, hawksbill, leatherback turtle, Atlantic ridley and olive ridley). Some species are threatened with extinction.[23] Their populations have been greatly reduced since the 17th century – the number of green turtles has declined from 91 million to 300,000 and hawksbill turtles from 11 million to less than 30,000 by 2006.[24]
+
+All 170 species of amphibians that live in the region are endemic. The habitats of almost all members of the toad family, poison dart frogs, tree frogs and leptodactylidae (a type of frog) are limited to only one island.[25] The Golden coqui is in serious threat of extinction.
+
+In the Caribbean 600 species of birds have been recorded of which 163 are endemic such as the tody, Fernandina's flicker and palmchat. The American yellow warbler is found in many areas as is the green heron. Of the endemic species 48 are threatened with extinction including the Puerto Rican amazon, yellow-breasted crake and the Zapata wren. According to Birdlife International in 2006 in Cuba 29 species of bird are in danger of extinction and two species officially extinct.[26] The black-fronted piping guan is endangered as is the plain pigeon. The Antilles along with Central America lie in the flight path of migrating birds from North America so the size of populations is subject to seasonal fluctuations. In the forests are found parrots, bananaquit and toucans. Over the open sea can be seen frigatebirds and tropicbirds.
+
+The Caribbean region has seen a significant increase in human activity since the colonization period. The sea is one of the largest oil production areas in the world, producing approximately 170 million tons[clarification needed] per year.[27] The area also generates a large fishing industry for the surrounding countries, accounting for 500,000 tonnes (490,000 long tons; 550,000 short tons) of fish a year.[28]
+
+Human activity in the area also accounts for a significant amount of pollution, The Pan American Health Organization estimated in 1993 that only about 10% of the sewage from the Central American and Caribbean Island countries is properly treated before being released into the sea.[27]
+
+The Caribbean region supports a large tourism industry. The Caribbean Tourism Organization calculates that about 12 million people a year visit the area, including (in 1991–1992) about 8 million cruise ship tourists. Tourism based upon scuba diving and snorkeling on coral reefs of many Caribbean islands makes a major contribution to their economies.[29]
+
+Sunrise over the south beach of Jamaica
+
+Los Roques Archipelago, Venezuela
+
+Marie Galante, Guadeloupe
+
+Beach of Curaçao
+
+Mona Island, Puerto Rico
+
+Palm Beach, Aruba
+
+Cayo Coco, Cuba
+
+Saint-Marc, Haiti

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+The Caribbean Sea (Spanish: Mar Caribe; French: Mer des Caraïbes; Haitian Creole: Lamè Karayib; Jamaican Patois: Kiaribiyan Sii; Dutch: Caraïbische Zee; Papiamento: Laman Karibe) is an American mediterranean sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico and Central America to the west and south west, to the north by the Greater Antilles starting with Cuba, to the east by the Lesser Antilles, and to the south by the north coast of South America.
+
+The entire area of the Caribbean Sea, the numerous islands of the West Indies, and adjacent coasts, are collectively known as the Caribbean. The Caribbean Sea is one of the largest seas and has an area of about 2,754,000 km2 (1,063,000 sq mi).[1][2] The sea's deepest point is the Cayman Trough, between the Cayman Islands and Jamaica, at 7,686 m (25,217 ft) below sea level. The Caribbean coastline has many gulfs and bays: the Gulf of Gonâve, Gulf of Venezuela, Gulf of Darién, Golfo de los Mosquitos, Gulf of Paria and Gulf of Honduras.
+
+The Caribbean Sea has the world's second largest barrier reef, the Mesoamerican Barrier Reef. It runs 1,000 km (620 mi) along the coasts of Mexico, Belize, Guatemala, and Honduras.[3]
+
+The name "Caribbean" derives from the Caribs, one of the region's dominant Native American groups at the time of European contact during the late 15th century. After Christopher Columbus landed in the Bahamas in 1492, the Spanish term Antillas applied to the lands; stemming from this, "Sea of the Antilles" became a common alternative name for "Caribbean Sea" in various European languages. During the first century of development, Spanish dominance in the region remained undisputed.
+
+From the 16th century, Europeans visiting the Caribbean region identified the "South Sea" (the Pacific Ocean, to the south of the isthmus of Panama) as opposed to the "North Sea" (the Caribbean Sea, to the north of the same isthmus).[4]
+
+The Caribbean Sea had been unknown to the populations of Eurasia until 1492, when Christopher Columbus sailed into Caribbean waters on a quest to find a sea route to Asia. At that time the Western Hemisphere in general was unknown to most Europeans, although it had been discovered between the years 800 and 1000 by the vikings. Following the discovery of the islands by Columbus, the area was quickly colonized by several Western cultures (initially Spain, then later England, the Dutch Republic, France, Courland and Denmark). Following the colonization of the Caribbean islands, the Caribbean Sea became a busy area for European-based marine trading and transports, and this commerce eventually attracted pirates such as Samuel Bellamy and Blackbeard.
+
+As of 2015[update] the area is home to 22 island territories and borders 12 continental countries.
+
+The International Hydrographic Organization defines the limits of the Caribbean Sea as follows:[5]
+
+Note that, although Barbados is an island on the same continental shelf, it is considered to be in the Atlantic Ocean rather than the Caribbean Sea.
+
+The Caribbean Sea is an oceanic sea largely situated on the Caribbean Plate. The Caribbean Sea is separated from the ocean by several island arcs of various ages. The youngest stretches from the Lesser Antilles to the Virgin Islands to the north east of Trinidad and Tobago off the coast of Venezuela. This arc was formed by the collision of the South American Plate with the Caribbean Plate and includes active and extinct volcanoes such as Mount Pelee, the Quill (volcano) on Sint Eustatius in the Caribbean Netherlands and Morne Trois Pitons on Dominica. The larger islands in the northern part of the sea Cuba, Hispaniola, Jamaica and Puerto Rico lie on an older island arc.
+
+The geological age of the Caribbean Sea is estimated to be between 160 and 180 million years and was formed by a horizontal fracture that split the supercontinent called Pangea in the Mesozoic Era.[8] It is assumed the proto-caribbean basin existed in the Devonian period. In the early Carboniferous movement of Gondwana to the north and its convergence with the Euramerica basin decreased in size. The next stage of the Caribbean Sea's formation began in the Triassic. Powerful rifting led to the formation of narrow troughs, stretching from modern Newfoundland to the west coast of the Gulf of Mexico which formed siliciclastic sedimentary rocks. In the early Jurassic due to powerful marine transgression, water broke into the present area of the Gulf of Mexico creating a vast shallow pool. The emergence of deep basins in the Caribbean occurred during the Middle Jurassic rifting. The emergence of these basins marked the beginning of the Atlantic Ocean and contributed to the destruction of Pangaea at the end of the late Jurassic. During the Cretaceous the Caribbean acquired the shape close to that seen today. In the early Paleogene due to Marine regression the Caribbean became separated from the Gulf of Mexico and the Atlantic Ocean by the land of Cuba and Haiti. The Caribbean remained like this for most of the Cenozoic until the Holocene when rising water levels of the oceans restored communication with the Atlantic Ocean.
+
+The Caribbean's floor is composed of sub-oceanic sediments of deep red clay in the deep basins and troughs. On continental slopes and ridges calcareous silts are found. Clay minerals likely having been deposited by the mainland river Orinoco and the Magdalena River. Deposits on the bottom of the Caribbean Sea and Gulf of Mexico have a thickness of about 1 km (0.62 mi). Upper sedimentary layers relate to the period from the Mesozoic to the Cenozoic (250 million years ago to present) and the lower layers from the Paleozoic to the Mesozoic.
+
+The Caribbean sea floor is divided into five basins separated from each other by underwater ridges and mountain ranges. Atlantic Ocean water enters the Caribbean through the Anegada Passage lying between the Lesser Antilles and Virgin Islands and the Windward Passage located between Cuba and Haiti. The Yucatán Channel between Mexico and Cuba links the Gulf of Mexico with the Caribbean. The deepest points of the sea lie in Cayman Trough with depths reaching approximately 7,686 m (25,220 ft). Despite this, the Caribbean Sea is considered a relatively shallow sea in comparison to other bodies of water.
+The pressure of the South American Plate to the east of the Caribbean causes the region of the Lesser Antilles to have high volcanic activity. There was a very serious eruption of Mount Pelée in 1902 which caused many casualties.
+
+The Caribbean sea floor is also home to two oceanic trenches: the Cayman Trench and Puerto Rico Trench, which put the area at a high risk of earthquakes. Underwater earthquakes pose a threat of generating tsunamis which could have a devastating effect on the Caribbean islands. Scientific data reveals that over the last 500 years the area has seen a dozen earthquakes above 7.5 magnitude.[9] Most recently, a 7.1 earthquake struck Haiti on January 12, 2010.
+
+The hydrology of the sea has a high level of homogeneity. Annual variations in monthly average water temperatures at the surface do not exceed 3 °C (5.4 °F). Over the past fifty years the Caribbean has gone through three stages: cooling until 1974; a cold phase with peaks during 1974–1976 and 1984–1986 then; a warming phase with an increase in temperature of 0.6 °C (1.1 °F) per year. Virtually all temperature extremes were associated with the phenomena of El Niño and La Niña. The salinity of seawater is about 3.6% and its density is 1,023.5–1,024.0 kg/m3 (63.90–63.93 lb/cu ft). The surface water colour is blue-green to green.
+
+The Caribbean's depth in its wider basins and deep water temperatures are similar to those of the Atlantic. Atlantic deep water is thought to spill into the Caribbean and contribute to the general deep water of its sea.[10] The surface water (30 m; 100 feet) acts as an extension of the northern Atlantic as the Guiana Current and part of the North Equatorial Current enter the sea on the east. On the western side of the sea the trade winds influence a northerly current which causes an upwelling and a rich fishery near Yucatán.[11]
+
+The Caribbean is home to about 9% of the world's coral reefs covering about 50,000 km2 (19,000 sq mi), most of which are located off the Caribbean Islands and the Central American coast.[12] Among them stands out the Belize Barrier Reef with an area of 963 km2 (372 sq mi) which was declared a World Heritage Site in 1996. It forms part of the Great Mayan Reef also known as the MBRS and being over 1,000 km (600 mi) in length is the world's second longest. It runs along the Caribbean coasts of Mexico, Belize, Guatemala and Honduras.
+
+During the past ten years,[when?] unusually warm Caribbean waters have been increasingly threatening Caribbean coral reefs. Coral reefs support some of the most diverse marine habitats in the world, but they are fragile ecosystems. When tropical waters become unusually warm for extended periods of time, microscopic plants called zooxanthellae, which are symbiotic partners living within the coral polyp tissues, die off. These plants provide food for the corals, and give them their color. The result of the death and dispersal of these tiny plants is called coral bleaching, and can lead to the devastation of large areas of reef. Over 42% of corals are completely bleached and 95% are experiencing some type of whitening.[13] Historically the Caribbean is thought to contain 14% of the world's coral reefs.[14]
+
+The habitats supported by the reefs are critical to such tourist activities as fishing and diving, and provide an annual economic value to Caribbean nations of US$3.1–4.6 billion. Continued destruction of the reefs could severely damage the region's economy.[15] A Protocol of the Convention for the Protection and Development of the Marine Environment of the Wider Caribbean Region came in effect in 1986 to protect the various endangered marine life of the Caribbean through forbidding human activities that would advance the continued destruction of such marine life in various areas. Currently this protocol has been ratified by 15 countries.[16] Also, several charitable organisations have been formed to preserve the Caribbean marine life, such as Caribbean Conservation Corporation which seeks to study and protect sea turtles while educating others about them.[17]
+
+In connection with the foregoing, the Institute of Marine Sciences and Limnology of the National Autonomous University of Mexico, conducted a regional study, funded by the Department of Technical Cooperation of the International Atomic Energy Agency, in which specialists from 11 Latin American countries (Colombia, Costa Rica, Cuba, Guatemala, Haiti, Honduras, Mexico, Nicaragua, Panama, Dominican Republic, Venezuela plus Jamaica) participated. The findings indicate that heavy metals such as mercury, arsenic, and lead, have been identified in the coastal zone of the Caribbean Sea. Analysis of toxic metals and hydrocarbons is based on the investigation of coastal sediments that have accumulated less than 50 meters deep during the last hundred and fifty years. The project results were presented in Vienna in the forum "Water Matters", and the 2011 General Conference of said multilateral organization.[18]
+
+The climate of the Caribbean is driven by the low latitude and tropical ocean currents that run through it. The principal ocean current is the North Equatorial Current, which enters the region from the tropical Atlantic. The climate of the area is tropical, varying from tropical rainforest in some areas to tropical savanna in others. There are also some locations that are arid climates with considerable drought in some years.
+
+Rainfall varies with elevation, size and water currents (cool upwelling keep the ABC islands arid). Warm, moist trade winds blow consistently from the east, creating both rain forest and semi arid climates across the region. The tropical rainforest climates include lowland areas near the Caribbean Sea from Costa Rica north to Belize, as well as the Dominican Republic and Puerto Rico, while the more seasonal dry tropical savanna climates are found in Cuba, northern Venezuela, and southern Yucatán, Mexico. Arid climates are found along the extreme southern coast of Venezuela out to the islands including Aruba and Curaçao, as well as the northern tip of Yucatán[20]
+
+Tropical cyclones are a threat to the nations that rim the Caribbean Sea. While landfalls are infrequent, the resulting loss of life and property damage makes them significant hazard to life in the Caribbean. Tropical cyclones that impact the Caribbean often develop off the West coast of Africa and make their way west across the Atlantic Ocean toward the Caribbean, while other storms develop in the Caribbean itself. The Caribbean hurricane season as a whole lasts from June through November, with the majority of hurricanes occurring during August and September. On average around 9 tropical storms form each year, with 5 reaching hurricane strength. According to the National Hurricane Center 385 hurricanes occurred in the Caribbean between 1494 and 1900.
+
+The region has a high level of biodiversity and many species are endemic to the Caribbean.
+
+The vegetation of the region is mostly tropical but differences in topography, soil and climatic conditions increase species diversity. Where there are porous limestone terraced islands these are generally poor in nutrients. It is estimated that 13,000 species of plants grow in the Caribbean of which 6,500 are endemic. For example, guaiac wood (Guaiacum officinale), the flower of which is the national flower of Jamaica and the Bayahibe rose (Pereskia quisqueyana) which is the national flower of the Dominican Republic and the ceiba which is the national tree of both Puerto Rico and Guatemala. The mahogany is the national tree of the Dominican Republic and Belize. The caimito (Chrysophyllum cainito) grows throughout the Caribbean. In coastal zones there are coconut palms and in lagoons and estuaries are found thick areas of black mangrove and red mangrove (Rhizophora mangle).
+
+In shallow water flora and fauna is concentrated around coral reefs where there is little variation in water temperature, purity and salinity. Leeward side of lagoons provide areas of growth for sea grasses. Turtle grass (Thalassia testudinum) is common in the Caribbean as is manatee grass (Syringodium filiforme) which can grow together as well as in fields of single species at depths up to 20 m (66 ft). Another type shoal grass (Halodule wrightii) grows on sand and mud surfaces at depths of up to 5 m (16 ft). In brackish water of harbours and estuaries at depths less than 2.5 m (8 ft 2 in) widgeongrass (Ruppia maritima) grows. Representatives of three species belonging to the genus Halophila, (Halophila baillonii, Halophila engelmannii and Halophila decipiens) are found at depths of up to 30 m (98 ft) except for Halophila engelmani which does not grow below 5 m (16 ft) and is confined to the Bahamas, Florida, the Greater Antilles and the western part of the Caribbean. Halophila baillonii has been found only in the Lesser Antilles.[21]
+
+Marine biota in the region have representatives of both the Indian and Pacific oceans which were caught in the Caribbean before the emergence of the Isthmus of Panama four million years ago.[22] In the Caribbean Sea there are around 1,000 documented species of fish, including sharks (bull shark, tiger shark, silky shark and Caribbean reef shark), flying fish, giant oceanic manta ray, angel fish, spotfin butterflyfish, parrotfish, Atlantic Goliath grouper, tarpon and moray eels. Throughout the Caribbean there is industrial catching of lobster and sardines (off the coast of Yucatán Peninsula).
+
+There are 90 species of mammals in the Caribbean including sperm whales, humpback whales and dolphins. The island of Jamaica is home to seals and manatees. The Caribbean monk seal which lived in the Caribbean is considered extinct. The solenodon is endangered.
+
+There are 500 species of reptiles (94% of which are endemic). Islands are inhabited by some endemic species such as rock iguanas and American crocodile. The blue iguana, endemic to the island of Grand Cayman, is endangered. The green iguana is invasive to Grand Cayman.  The Mona ground iguana which inhabits the island of Mona, Puerto Rico, is endangered. The rhinoceros iguana from the island of Hispaniola which is shared between Haiti and the Dominican Republic is also endangered. The region has several types of sea turtle (loggerhead, green turtle, hawksbill, leatherback turtle, Atlantic ridley and olive ridley). Some species are threatened with extinction.[23] Their populations have been greatly reduced since the 17th century – the number of green turtles has declined from 91 million to 300,000 and hawksbill turtles from 11 million to less than 30,000 by 2006.[24]
+
+All 170 species of amphibians that live in the region are endemic. The habitats of almost all members of the toad family, poison dart frogs, tree frogs and leptodactylidae (a type of frog) are limited to only one island.[25] The Golden coqui is in serious threat of extinction.
+
+In the Caribbean 600 species of birds have been recorded of which 163 are endemic such as the tody, Fernandina's flicker and palmchat. The American yellow warbler is found in many areas as is the green heron. Of the endemic species 48 are threatened with extinction including the Puerto Rican amazon, yellow-breasted crake and the Zapata wren. According to Birdlife International in 2006 in Cuba 29 species of bird are in danger of extinction and two species officially extinct.[26] The black-fronted piping guan is endangered as is the plain pigeon. The Antilles along with Central America lie in the flight path of migrating birds from North America so the size of populations is subject to seasonal fluctuations. In the forests are found parrots, bananaquit and toucans. Over the open sea can be seen frigatebirds and tropicbirds.
+
+The Caribbean region has seen a significant increase in human activity since the colonization period. The sea is one of the largest oil production areas in the world, producing approximately 170 million tons[clarification needed] per year.[27] The area also generates a large fishing industry for the surrounding countries, accounting for 500,000 tonnes (490,000 long tons; 550,000 short tons) of fish a year.[28]
+
+Human activity in the area also accounts for a significant amount of pollution, The Pan American Health Organization estimated in 1993 that only about 10% of the sewage from the Central American and Caribbean Island countries is properly treated before being released into the sea.[27]
+
+The Caribbean region supports a large tourism industry. The Caribbean Tourism Organization calculates that about 12 million people a year visit the area, including (in 1991–1992) about 8 million cruise ship tourists. Tourism based upon scuba diving and snorkeling on coral reefs of many Caribbean islands makes a major contribution to their economies.[29]
+
+Sunrise over the south beach of Jamaica
+
+Los Roques Archipelago, Venezuela
+
+Marie Galante, Guadeloupe
+
+Beach of Curaçao
+
+Mona Island, Puerto Rico
+
+Palm Beach, Aruba
+
+Cayo Coco, Cuba
+
+Saint-Marc, Haiti

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+
+
+The North Sea is a sea of the Atlantic Ocean located between Great Britain (England and Scotland), Denmark, Norway, Germany, the Netherlands, Belgium and France. An epeiric (or "shelf") sea on the European continental shelf, it connects to the ocean through the English Channel in the south and the Norwegian Sea in the north. It is more than 970 kilometres (600 mi) long and 580 kilometres (360 mi) wide, with an area of 570,000 square kilometres (220,000 sq mi).
+
+The North Sea has long been the site of important European shipping lanes as well as a major fishery. The coast is a popular destination for recreation and tourism in bordering countries, and more recently the sea has developed into a rich source of energy resources, including fossil fuels, wind, and early efforts in wave power.
+
+Historically, the North Sea has featured prominently in geopolitical and military affairs, particularly in Northern Europe. It was also important globally through the power northern Europeans projected worldwide during much of the Middle Ages and into the modern era. The North Sea was the centre of the Vikings' rise. Subsequently, the Hanseatic League, the Dutch Republic, and the British each sought to gain command the North Sea and thus access to the world's markets and resources. As Germany's only outlet to the ocean, the North Sea continued to be strategically important through both World Wars.
+
+The coast of the North Sea presents a diversity of geological and geographical features. In the north, deep fjords and sheer cliffs mark the Norwegian and Scottish coastlines, whereas in the south, the coast consists primarily of sandy beaches and wide mudflats. Due to the dense population, heavy industrialization, and intense use of the sea and area surrounding it, there have been various environmental issues affecting the sea's ecosystems. Adverse environmental issues – commonly including overfishing, industrial and agricultural runoff, dredging, and dumping, among others – have led to a number of efforts to prevent degradation of the sea while still making use of its economic potential.
+
+The North Sea is bounded by the Orkney Islands and east coast of Great Britain to the west[1] and the northern and central European mainland to the east and south, including Norway, Denmark, Germany, the Netherlands, Belgium, and France.[2] In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean.[1][2] In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat,[2] narrow straits that separate Denmark from Norway and Sweden respectively.[1] In the north it is bordered by the Shetland Islands, and connects with the Norwegian Sea, which is a marginal sea in the Arctic Ocean.[1][3]
+
+The North Sea is more than 970 kilometres (600 mi) long and 580 kilometres (360 mi) wide, with an area of 570,000 square kilometres (220,000 sq mi) and a volume of 54,000 cubic kilometres (13,000 cu mi).[4] Around the edges of the North Sea are sizeable islands and archipelagos, including Shetland, Orkney, and the Frisian Islands.[2] The North Sea receives freshwater from a number of European continental watersheds, as well as the British Isles. A large part of the European drainage basin empties into the North Sea, including water from the Baltic Sea. The largest and most important rivers flowing into the North Sea are the Elbe and the Rhine – Meuse.[5] Around 185 million people live in the catchment area of the rivers discharging into the North Sea encompassing some highly industrialized areas.[6]
+
+For the most part, the sea lies on the European continental shelf with a mean depth of 90 metres (300 ft).[1][7] The only exception is the Norwegian trench, which extends parallel to the Norwegian shoreline from Oslo to an area north of Bergen.[1] It is between 20 and 30 kilometres (12 and 19 mi) wide and has a maximum depth of 725 metres (2,379 ft).[8]
+
+The Dogger Bank, a vast moraine, or accumulation of unconsolidated glacial debris, rises to a mere 15 to 30 m (50 to 100 ft) below the surface.[9][10] This feature has produced the finest fishing location of the North Sea.[1] The Long Forties and the Broad Fourteens are large areas with roughly uniform depth in fathoms, (forty fathoms and fourteen fathoms or 73 and 26 m or 240 and 85 ft deep respectively). These great banks and others make the North Sea particularly hazardous to navigate,[11] which has been alleviated by the implementation of satellite navigation systems.[12] The Devil's Hole lies 200 miles (320 km) east of Dundee, Scotland. The feature is a series of asymmetrical trenches between 20 and 30 kilometres (12 and 19 mi) long, one and two kilometres (0.6 and 1.2 mi) wide and up to 230 metres (750 ft) deep.[13]
+
+Other areas which are less deep are Cleaver Bank, Fisher Bank and Noordhinder Bank.
+
+The International Hydrographic Organization defines the limits of the North Sea as follows:[14]
+
+On the Southwest. A line joining the Walde Lighthouse (France, 1°55'E) and Leathercoat Point (England, 51°10'N).[15]
+
+On the Northwest. From Dunnet Head (3°22'W) in Scotland to Tor Ness (58°47'N) in the Island of Hoy, thence through this island to the Kame of Hoy (58°55'N) on to Breck Ness on Mainland (58°58'N) through this island to Costa Head (3°14'W) and to Inga Ness (59'17'N) in Westray through Westray, to Bow Head, across to Mull Head (North point of Papa Westray) and on to Seal Skerry (North point of North Ronaldsay) and thence to Horse Island (South point of the Shetland Islands).
+
+On the North. From the North point (Fethaland Point) of the Mainland of the Shetland Islands, across to Graveland Ness (60°39'N) in the Island of Yell, through Yell to Gloup Ness (1°04'W) and across to Spoo Ness (60°45'N) in Unst island, through Unst to Herma Ness (60°51'N), on to the SW point of the Rumblings and to Muckle Flugga (60°51′N 0°53′W / 60.850°N 0.883°W / 60.850; -0.883) all these being included in the North Sea area; thence up the meridian of 0°53' West to the parallel of 61°00' North and eastward along this parallel to the coast of Norway, the whole of Viking Bank being thus included in the North Sea.
+
+On the East. The Western limit of the Skagerrak [A line joining Hanstholm (57°07′N 8°36′E / 57.117°N 8.600°E / 57.117; 8.600) and the Naze (Lindesnes, 58°N 7°E / 58°N 7°E / 58; 7)].
+
+The average temperature in summer is 17 °C (63 °F) and 6 °C (43 °F) in the winter.[4] The average temperatures have been trending higher since 1988, which has been attributed to climate change.[16][17] Air temperatures in January range on average between 0 to 4 °C (32 to 39 °F) and in July between 13 to 18 °C (55 to 64 °F). The winter months see frequent gales and storms.[1]
+
+The salinity averages between 34 and 35 grams per litre (129 and 132 g/US gal) of water.[4] The salinity has the highest variability where there is fresh water inflow, such as at the Rhine and Elbe estuaries, the Baltic Sea exit and along the coast of Norway.[18]
+
+The main pattern to the flow of water in the North Sea is an anti-clockwise rotation along the edges.[19]
+
+The North Sea is an arm of the Atlantic Ocean receiving the majority of ocean current from the northwest opening, and a lesser portion of warm current from the smaller opening at the English Channel. These tidal currents leave along the Norwegian coast.[20] Surface and deep water currents may move in different directions. Low salinity surface coastal waters move offshore, and deeper, denser high salinity waters move inshore.[21]
+
+The North Sea located on the continental shelf has different waves from those in deep ocean water. The wave speeds are diminished and the wave amplitudes are increased. In the North Sea there are two amphidromic systems and a third incomplete amphidromic system.[22][23] In the North Sea the average tide difference in wave amplitude is between zero and eight metres (26 ft).[An average is a single figure, not a range.][4]
+
+The Kelvin tide of the Atlantic Ocean is a semidiurnal wave that travels northward. Some of the energy from this wave travels through the English Channel into the North Sea. The wave continues to travel northward in the Atlantic Ocean, and once past the northern tip of Great Britain, the Kelvin wave turns east and south and once again enters the North Sea.[24]
+
+The eastern and western coasts of the North Sea are jagged, formed by glaciers during the ice ages. The coastlines along the southernmost part are covered with the remains of deposited glacial sediment.[1] The Norwegian mountains plunge into the sea creating deep fjords and archipelagos. South of Stavanger, the coast softens, the islands become fewer.[1] The eastern Scottish coast is similar, though less severe than Norway. From north east of England, the cliffs become lower and are composed of less resistant moraine, which erodes more easily, so that the coasts have more rounded contours.[59][60] In the Netherlands, Belgium and in East Anglia the littoral is low and marshy.[1] The east coast and south-east of the North Sea (Wadden Sea) have coastlines that are mainly sandy and straight owing to longshore drift, particularly along Belgium and Denmark.[61]
+
+The southern coastal areas were originally amphibious flood plains and swampy land. In areas especially vulnerable to storm surges, people settled behind elevated levees and on natural areas of high ground such as spits and geestland.[62]:[302,303] As early as 500 BC, people were constructing artificial dwelling hills higher than the prevailing flood levels.[62]:[306,308] It was only around the beginning of the High Middle Ages, in 1200 AD, that inhabitants began to connect single ring dikes into a dike line along the entire coast, thereby turning amphibious regions between the land and the sea into permanent solid ground.[62]
+
+The modern form of the dikes supplemented by overflow and lateral diversion channels, began to appear in the 17th and 18th centuries, built in the Netherlands.[63] The North Sea Floods of 1953 and 1962 were the impetus for further raising of the dikes as well as the shortening of the coast line so as to present as little surface area as possible to the punishment of the sea and the storms.[64] Currently, 27% of the Netherlands is below sea level protected by dikes, dunes, and beach flats.[65]
+
+Coastal management today consists of several levels.[66] The dike slope reduces the energy of the incoming sea, so that the dike itself does not receive the full impact.[66] Dikes that lie directly on the sea are especially reinforced.[66] The dikes have, over the years, been repeatedly raised, sometimes up to 9 metres (30 ft) and have been made flatter to better reduce wave erosion.[67] Where the dunes are sufficient to protect the land behind them from the sea, these dunes are planted with beach grass (Ammophila arenaria) to protect them from erosion by wind, water, and foot traffic.[68]
+
+Storm surges threaten, in particular, the coasts of the Netherlands, Belgium, Germany, and Denmark and low lying areas of eastern England particularly around The Wash and Fens.[61]
+Storm surges are caused by changes in barometric pressure combined with strong wind created wave action.[69]
+
+The first recorded storm tide flood was the Julianenflut, on 17 February 1164. In its wake, the Jadebusen, (a bay on the coast of Germany), began to form.
+A storm tide in 1228 is recorded to have killed more than 100,000 people.[70] In 1362, the Second Marcellus Flood, also known as the Grote Manndrenke, hit the entire southern coast of the North Sea. Chronicles of the time again record more than 100,000 deaths, large parts of the coast were lost permanently to the sea, including the now legendary lost city of Rungholt.[71]
+In the 20th century, the North Sea flood of 1953 flooded several nations' coasts and cost more than 2,000 lives.[72]
+315 citizens of Hamburg died in the North Sea flood of 1962.[73]:[79,86]
+
+Though rare, the North Sea has been the site of a number of historically documented tsunamis. The Storegga Slides were a series of underwater landslides, in which a piece of the Norwegian continental shelf slid into the Norwegian Sea. The immense landslips occurred between 8150 BCE and 6000 BCE, and caused a tsunami up to 20 metres (66 ft) high that swept through the North Sea, having the greatest effect on Scotland and the Faeroe Islands.[74][75]
+The Dover Straits earthquake of 1580 is among the first recorded earthquakes in the North Sea measuring between 5.6 and 5.9 on the Richter scale. This event caused extensive damage in Calais both through its tremors and possibly triggered a tsunami, though this has never been confirmed. The theory is a vast underwater landslide in the English Channel was triggered by the earthquake, which in turn caused a tsunami.[76] The tsunami triggered by the 1755 Lisbon earthquake reached Holland, although the waves had lost their destructive power. The largest earthquake ever recorded in the United Kingdom was the 1931 Dogger Bank earthquake, which measured 6.1 on the Richter magnitude scale and caused a small tsunami that flooded parts of the British coast.[76]
+
+Shallow epicontinental seas like the current North Sea have since long existed on the European continental shelf. The rifting that formed the northern part of the Atlantic Ocean during the Jurassic and Cretaceous periods, from about 150 million years ago, caused tectonic uplift in the British Isles.[77] Since then, a shallow sea has almost continuously existed between the uplands of the Fennoscandian Shield and the British Isles.[78] This precursor of the current North Sea has grown and shrunk with the rise and fall of the eustatic sea level during geologic time. Sometimes it was connected with other shallow seas, such as the sea above the Paris Basin to the south-west, the Paratethys Sea to the south-east, or the Tethys Ocean to the south.[79]
+
+During the Late Cretaceous, about 85 million years ago, all of modern mainland Europe except for Scandinavia was a scattering of islands.[80] By the Early Oligocene, 34 to 28 million years ago, the emergence of Western and Central Europe had almost completely separated the North Sea from the Tethys Ocean, which gradually shrank to become the Mediterranean as Southern Europe and South West Asia became dry land.[81] The North Sea was cut off from the English Channel by a narrow land bridge until that was breached by at least two catastrophic floods between 450,000 and 180,000 years ago.[82][83] Since the start of the Quaternary period about 2.6 million years ago, the eustatic sea level has fallen during each glacial period and then risen again. Every time the ice sheet reached its greatest extent, the North Sea became almost completely dry. The present-day coastline formed after the Last Glacial Maximum when the sea began to flood the European continental shelf.[84]
+
+In 2006 a bone fragment was found while drilling for oil in the North Sea. Analysis indicated that it was a Plateosaurus from 199 to 216 million years ago. This was the deepest dinosaur fossil ever found and the first find for Norway.[85]
+
+Copepods and other zooplankton are plentiful in the North Sea. These tiny organisms are crucial elements of the food chain supporting many species of fish.[86] Over 230 species of fish live in the North Sea. Cod, haddock, whiting, saithe, plaice, sole, mackerel, herring, pouting, sprat, and sandeel are all very common and are fished commercially.[86][87] Due to the various depths of the North Sea trenches and differences in salinity, temperature, and water movement, some fish such as blue-mouth redfish and rabbitfish reside only in small areas of the North Sea.[88]
+
+Crustaceans are also commonly found throughout the sea. Norway lobster, deep-water prawns, and brown shrimp are all commercially fished, but other species of lobster, shrimp, oyster, mussels and clams all live in the North Sea.[86] Recently non-indigenous species have become established including the Pacific oyster and Atlantic jackknife clam.[87]
+
+The coasts of the North Sea are home to nature reserves including the Ythan Estuary, Fowlsheugh Nature Preserve, and Farne Islands in the UK and the Wadden Sea National Parks in Denmark, Germany and the Netherlands.[86] These locations provide breeding habitat for dozens of bird species. Tens of millions of birds make use of the North Sea for breeding, feeding, or migratory stopovers every year. Populations of black-legged kittiwakes, Atlantic puffins, northern gannets, northern fulmars, and species of petrels,  seaducks, loons (divers), cormorants, gulls, auks, and terns, and many other seabirds make these coasts popular for birdwatching.[86][87]
+
+The North Sea is also home to marine mammals. Common seals, and harbour porpoises can be found along the coasts, at marine installations, and on islands. The very northern North Sea islands such as the Shetland Islands are occasionally home to a larger variety of pinnipeds including bearded, harp, hooded and ringed seals, and even walrus.[89] North Sea cetaceans include various porpoise, dolphin and whale species.[87][90]
+
+Plant species in the North Sea include species of wrack, among them bladder wrack, knotted wrack, and serrated wrack. Algae, macroalgal, and kelp, such as oarweed and laminaria hyperboria, and species of maerl are found as well.[87] Eelgrass, formerly common in the entirety of the Wadden Sea, was nearly wiped out in the 20th century by a disease.[91] Similarly, sea grass used to coat huge tracts of ocean floor, but have been damaged by trawling and dredging have diminished its habitat and prevented its return.[92] Invasive Japanese seaweed has spread along the shores of the sea clogging harbours and inlets and has become a nuisance.[93]
+
+Due to the heavy human populations and high level of industrialization along its shores, the wildlife of the North Sea has suffered from pollution, overhunting, and overfishing. Flamingos and pelicans were once found along the southern shores of the North Sea, but became extinct over the 2nd millennium.[94] Walruses frequented the Orkney Islands through the mid-16th century, as both Sable Island and Orkney Islands lay within its normal range.[95] Gray whales also resided in the North Sea but were driven to extinction in the Atlantic in the 17th century[96] Other species have dramatically declined in population, though they are still found. North Atlantic right whales, sturgeon, shad, rays, skates, salmon, and other species were common in the North Sea until the 20th century, when numbers declined due to overfishing.[97][98]
+Other factors like the introduction of non-indigenous species, industrial and agricultural pollution, trawling and dredging, human-induced eutrophication, construction on coastal breeding and feeding grounds, sand and gravel extraction, offshore construction, and heavy shipping traffic have also contributed to the decline.[87]
+For example, a resident killer whale pod was lost in the 1960s, presumably due to the peak in PCB pollution in this time period.[99]
+
+The OSPAR commission manages the OSPAR convention to counteract the harmful effects of human activity on wildlife in the North Sea, preserve endangered species, and provide environmental protection.[100] All North Sea border states are signatories of the MARPOL 73/78 Accords, which preserve the marine environment by preventing pollution from ships.[101]
+Germany, Denmark, and the Netherlands also have a trilateral agreement for the protection of the Wadden Sea, or mudflats, which run along the coasts of the three countries on the southern edge of the North Sea.[102]
+
+The North Sea has had various names through history. One of the earliest recorded names was Septentrionalis Oceanus, or "Northern Ocean," which was cited by Pliny.[103] The name "North Sea" probably came into English, however, via the Dutch "Noordzee", who named it thus either in contrast with the Zuiderzee ("South Sea"), located south of Frisia, or because the sea is generally to the north of the Netherlands. Before the adoption of "North Sea," the names used in English, in American English in particular, were "German Sea" or "German Ocean", referred to the Latin names "Mare Germanicum" and "Oceanus Germanicus",[104] and these persisted in use until the First World War.[105]
+
+Other common names in use for long periods were the Latin terms "Mare Frisicum",[106] as well as the English equivalent, "Frisian Sea".[107]
+
+The modern names of the sea in the other local languages are: Danish: Vesterhavet [ˈvestɐˌhɛˀvð̩] ("West Sea") or Nordsøen [ˈnoɐ̯ˌsøˀn̩], Dutch: Noordzee, Dutch Low Saxon: Noordzee, French: Mer du Nord, West Frisian: Noardsee, German: Nordsee, Low German: Noordsee, Northern Frisian: Weestsiie ("West Sea"), Norwegian: Nordsjøen [ˈnûːrˌʂøːn], Nynorsk: Nordsjøen, Scots: German Ocean, Est se ("East Sea"), Scottish Gaelic: An Cuan a Tuath, West Flemish: Nôordzêe and Zeeuws: Noôrdzeê.
+
+North Sea has provided waterway access for commerce and conquest. Many areas have access to the North Sea because of its long coastline and the European rivers that empty into it.[1] The British Isles had been protected from invasion by the North Sea waters[1] until the Roman conquest of Britain in 43 CE. The Romans established organised ports, which increased shipping, and began sustained trade.[108] When the Romans abandoned Britain in 410, the Germanic Angles, Saxons, and Jutes began the next great migration across the North Sea during the Migration Period. They made successive invasions of the island.[109]
+
+The Viking Age began in 793 with the attack on Lindisfarne; for the next quarter-millennium the Vikings ruled the North Sea. In their superior longships, they raided, traded, and established colonies and outposts along the coasts of the sea. From the Middle Ages through the 15th century, the northern European coastal ports exported domestic goods, dyes, linen, salt, metal goods and wine. The Scandinavian and Baltic areas shipped grain, fish, naval necessities, and timber. In turn the North Sea countries imported high-grade cloths, spices, and fruits from the Mediterranean region.[110] Commerce during this era was mainly conducted by maritime trade due to underdeveloped roadways.[110]
+
+In the 13th century the Hanseatic League, though centred on the Baltic Sea, started to control most of the trade through important members and outposts on the North Sea.[111] The League lost its dominance in the 16th century, as neighbouring states took control of former Hanseatic cities and outposts. Their internal conflict prevented effective cooperation and defence.[112] As the League lost control of its maritime cities, new trade routes emerged that provided Europe with Asian, American, and African goods.[113][114]
+
+The 17th century Dutch Golden Age during which Dutch herring, cod and whale fisheries reached an all time high[110] saw Dutch power at its zenith.[115][116] Important overseas colonies, a vast merchant marine, powerful navy and large profits made the Dutch the main challengers to an ambitious England. This rivalry led to the first three Anglo-Dutch Wars between 1652 and 1673, which ended with Dutch victories.[116] After the Glorious Revolution in 1688, the Dutch prince William ascended to the English throne. With unified leadership, commercial, military, and political power began to shift from Amsterdam to London.[117]
+The British did not face a challenge to their dominance of the North Sea until the 20th century.[118]
+
+Tensions in the North Sea were again heightened in 1904 by the Dogger Bank incident. During the Russo-Japanese War, several ships of the Russian Baltic Fleet, which was on its way to the Far East, mistook British fishing boats for Japanese ships and fired on them, and then upon each other, near the Dogger Bank, nearly causing Britain to enter the war on the side of Japan.
+
+During the First World War, Great Britain's Grand Fleet and Germany's Kaiserliche Marine faced each other in the North Sea,[119] which became the main theatre of the war for surface action.[119] Britain's larger fleet and North Sea Mine Barrage were able to establish an effective blockade for most of the war, which restricted the Central Powers' access to many crucial resources.[120] Major battles included the Battle of Heligoland Bight,[121] the Battle of the Dogger Bank,[122] and the Battle of Jutland.[122]
+World War I also brought the first extensive use of submarine warfare, and a number of submarine actions occurred in the North Sea.[123]
+
+The Second World War also saw action in the North Sea,[124] though it was restricted more to aircraft reconnaissance, and action by fighter/bomber aircraft, submarines, and smaller vessels such as minesweepers and torpedo boats.[125]
+
+In the aftermath of the war, hundreds of thousands of tons of chemical weapons were disposed of by being dumped in the North Sea.[126]
+
+After the war, the North Sea lost much of its military significance because it is bordered only by NATO member-states. However, it gained significant economic importance in the 1960s as the states around the North Sea began full-scale exploitation of its oil and gas resources.[127] The North Sea continues to be an active trade route.[128]
+
+Countries that border the North Sea all claim the 12 nautical miles (22 km; 14 mi) of territorial waters, within which they have exclusive fishing rights.[129] The Common Fisheries Policy of the European Union (EU) exists to coordinate fishing rights and assist with disputes between EU states and the EU border state of Norway.[130]
+
+After the discovery of mineral resources in the North Sea, the Convention on the Continental Shelf established country rights largely divided along the median line. The median line is defined as the line "every point of which is equidistant from the nearest points of the baselines from which the breadth of the territorial sea of each State is measured."[131]
+The ocean floor border between Germany, the Netherlands, and Denmark was only reapportioned after protracted negotiations and a judgement of the International Court of Justice.[129][132]
+
+As early as 1859, oil was discovered in onshore areas around the North Sea and natural gas as early as 1910.[80] Onshore resources, for example the K12-B field in the Netherlands continue to be exploited today.
+
+Offshore test drilling began in 1966 and then, in 1969, Phillips Petroleum Company discovered the Ekofisk oil field[133] distinguished by valuable, low-sulphur oil.[134] Commercial exploitation began in 1971 with tankers and, after 1975, by a pipeline, first to Teesside, England and then, after 1977, also to Emden, Germany.[135]
+
+The exploitation of the North Sea oil reserves began just before the 1973 oil crisis, and the climb of international oil prices made the large investments needed for extraction much more attractive.[136]
+The start in 1973 of the oil reserves by UK allowed them to stop the declining position in the international trade in 1974, and a huge increase after the discovery and exploitation of the huge oil field by Phillips group in 1977 as the Brae field.
+
+Although the production costs are relatively high, the quality of the oil, the political stability of the region, and the proximity of important markets in western Europe has made the North Sea an important oil-producing region.[134] The largest single humanitarian catastrophe in the North Sea oil industry was the destruction of the offshore oil platform Piper Alpha in 1988 in which 167 people lost their lives.[137]
+
+Besides the Ekofisk oil field, the Statfjord oil field is also notable as it was the cause of the first pipeline to span the Norwegian trench.[138] The largest natural gas field in the North Sea, Troll gas field, lies in the Norwegian trench, dropping over 300 metres (980 ft), requiring the construction of the enormous Troll A platform to access it.
+
+The price of Brent Crude, one of the first types of oil extracted from the North Sea, is used today as a standard price for comparison for crude oil from the rest of the world.[139] The North Sea contains western Europe's largest oil and natural gas reserves and is one of the world's key non-OPEC producing regions.[140]
+
+In the UK sector of the North Sea, the oil industry invested £14.4 billion in 2013, and was on track to spend £13 billion in 2014. Industry body Oil & Gas UK put the decline down to rising costs, lower production, high tax rates, and less exploration.[141]
+
+As of January 2018 The North Sea region contains 184 offshore rigs, which makes it the region with the highest number of offshore rigs in the world.[142]
+
+The North Sea is Europe's main fishery accounting for over 5% of international commercial fish caught.[1] Fishing in the North Sea is concentrated in the southern part of the coastal waters. The main method of fishing is trawling.[143]
+In 1995, the total volume of fish and shellfish caught in the North Sea was approximately 3.5 million tonnes.[144] Besides fish, it is estimated that one million tonnes of unmarketable by-catch is caught and discarded each year.[145]
+
+In recent decades, overfishing has left many fisheries unproductive, disturbing marine food chain dynamics and costing jobs in the fishing industry.[146] Herring, cod and plaice fisheries may soon face the same plight as mackerel fishing, which ceased in the 1970s due to overfishing.[147]
+The objective of the European Union Common Fisheries Policy is to minimize the environmental impact associated with resource use by reducing fish discards, increasing productivity of fisheries, stabilising markets of fisheries and fish processing, and supplying fish at reasonable prices for the consumer.[148]
+
+Whaling was an important economic activity from the 9th until the 13th century for Flemish whalers.[149] The medieval Flemish, Basque and Norwegian whalers who were replaced in the 16th century by Dutch, English, Danes and Germans, took massive numbers of whales and dolphins and nearly depleted the right whales. This activity likely led to the extinction of the Atlantic population of the once common gray whale.[150] By 1902 the whaling had ended.[149] After being absent for 300 years a single gray whale returned,[151] it probably was the first of many more to find its way through the now ice-free Northwest Passage.
+
+In addition to oil, gas, and fish, the states along the North Sea also take millions of cubic metres per year of sand and gravel from the ocean floor. These are used for beach nourishment, land reclamation
+and construction.[152]
+Rolled pieces of amber may be picked up on the east coast of England.[153]
+
+Due to the strong prevailing winds, and shallow water, countries on the North Sea, particularly Germany and Denmark, have used the shore for wind power since the 1990s.[154] The North Sea is the home of one of the first large-scale offshore wind farms in the world, Horns Rev 1, completed in 2002. Since then many other wind farms have been commissioned in the North Sea (and elsewhere). As of 2013 the 630 megawatt (MW) London Array is the largest offshore wind farm in the world, with the 504 (MW) Greater Gabbard wind farm the second largest, followed by the 367 MW Walney Wind Farm. All are off the coast of the UK. These projects will be dwarfed by subsequent wind farms that are in the pipeline, including Dogger Bank at 4,800 MW, Norfolk Bank (7,200 MW), and Irish Sea (4,200 MW). At the end of June 2013 total European combined offshore wind energy capacity was 6,040 MW. UK installed 513.5 MW offshore windpower in the first half-year of 2013.[155]
+
+The expansion of offshore wind farms has met with some resistance. Concerns have included shipping collisions[156] and environmental effects on ocean ecology and wildlife such as fish and migratory birds,[157] however, these concerns were found to be negligible in a long-term study in Denmark released in 2006 and again in a UK government study in 2009.[158][159]
+There are also concerns about reliability,[160] and the rising costs of constructing and maintaining offshore wind farms.[161] Despite these, development of North Sea wind power is continuing, with plans for additional wind farms off the coasts of Germany, the Netherlands, and the UK.[162] There have also been proposals for a transnational power grid in the North Sea[163][164] to connect new offshore wind farms.[165]
+
+Energy production from tidal power is still in a pre-commercial stage. The European Marine Energy Centre has installed a wave testing system at Billia Croo on the Orkney mainland[166] and a tidal power testing station on the nearby island of Eday.[167] Since 2003, a prototype Wave Dragon energy converter has been in operation at Nissum Bredning fjord of northern Denmark.[168]
+
+The beaches and coastal waters of the North Sea are destinations for tourists. The Belgian, Dutch, German and Danish coasts[169][170] are developed for tourism. The North Sea coast of the United Kingdom has tourist destinations with beach resorts and golf courses. Fife in Scotland is famous for its links golf courses; the coastal city of St. Andrews is renowned as the "Home of Golf". The coast of North East England has several tourist towns such as Scarborough, Bridlington, Seahouses, Whitby, Robin Hood's Bay and Seaton Carew, and has some long sandy beaches and links golfing locations such as Seaton Carew Golf Club and Goswick Golf Club.
+
+The North Sea Trail is a long-distance trail linking seven countries around the North Sea.[171] Windsurfing and sailing[172] are popular sports because of the strong winds. Mudflat hiking,[173] recreational fishing and birdwatching[170] are among other activities.
+
+The climatic conditions on the North Sea coast have been claimed to be healthy. As early as the 19th century, travellers visited the North Sea coast for curative and restorative vacations. The sea air, temperature, wind, water, and sunshine are counted among the beneficial conditions that are said to activate the body's defences, improve circulation, strengthen the immune system, and have healing effects on the skin and the respiratory system.[174]
+
+The Wadden Sea in Denmark, Germany and the Netherlands is an UNESCO World Heritage Site.
+
+The North Sea is important for marine transport and its shipping lanes are among the busiest in the world.[129] Major ports are located along its coasts: Rotterdam, the busiest port in Europe and the fourth busiest port in the world by tonnage as of 2013[update], Antwerp (was 16th) and Hamburg (was 27th), Bremen/Bremerhaven and Felixstowe, both in the top 30 busiest container seaports,[175] as well as the Port of Bruges-Zeebrugge, Europe's leading ro-ro port.[176]
+
+Fishing boats, service boats for offshore industries, sport and pleasure craft, and merchant ships to and from North Sea ports and Baltic ports must share routes on the North Sea. The Dover Strait alone sees more than 400 commercial vessels a day.[177] Because of this volume, navigation in the North Sea can be difficult in high traffic zones, so ports have established elaborate vessel traffic services to monitor and direct ships into and out of port.[178]
+
+The North Sea coasts are home to numerous canals and canal systems to facilitate traffic between and among rivers, artificial harbours, and the sea. The Kiel Canal, connecting the North Sea with the Baltic Sea, is the most heavily used artificial seaway in the world reporting an average of 89 ships per day not including sporting boats and other small watercraft in 2009.[179] It saves an average of 250 nautical miles (460 km; 290 mi), instead of the voyage around the Jutland peninsula.[180] The North Sea Canal connects Amsterdam with the North Sea.

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+
+
+The Aegean Sea[a] is an elongated embayment of the Mediterranean Sea located between the Greek and Anatolian peninsulas. The sea has an area of some 215,000 square kilometres.[2] In the north, the Aegean is connected to the Marmara Sea and the Black Sea by the straits of the Dardanelles and Bosphorus. The Aegean Islands are located within the sea and some bound it on its southern periphery, including Crete and Rhodes. The sea reaches a maximum depth of 3,544 meters, to the east of Crete.
+
+The Aegean Islands can be divided into several island groups, including Dodecanese, the Cyclades, the Sporades, the Saronic islands and the North Aegean Islands, as well as Crete and its surrounding islands. The Dodecanese, located to the southeast, includes the islands of Rhodes, Kos, and Patmos; the islands of Delos and Naxos are within the Cyclades to the south of the sea. Lesbos is part of the North Aegean Islands. Euboea, the second largest island in Greece, is located in the Aegean, despite being administered as part of Central Greece. Nine out of twelve of the Administrative regions of Greece border the sea, along with the Turkish provinces of Edirne, Canakkale, Balıkesir, Izmir, Aydın and Muğla to the east of the sea. Various Turkish islands in the sea are Imbros, Tenedos, Cunda Island, and the Foça Islands.
+
+The Aegean Sea has been historically important, especially in regards to the civilization of Ancient Greece, who inhabited the area around the coast of the Aegean and the Aegean islands. The Aegean islands facilitated contact between the people of the area and between Europe and Asia. Along with the Greeks, Thracians lived among the northern coast. The Romans conquered the area under the Roman Empire, and later the Byzantine Empire held it against advances by the First Bulgarian Empire. The Fourth Crusade weakened Byzantine control of the area, and it was eventually conquered by the Ottoman Empire, with the exception of Crete, which was a Venetian colony until 1669. The Greek War of Independence allowed a Greek state on the coast of the Aegean from 1829 onwards. The Ottoman Empire held a presence over the sea for over 500 years, until it was replaced by modern Turkey.
+
+The rocks making up the floor of the Aegean are mainly limestone, though often greatly altered by volcanic activity that has convulsed the region in relatively recent geologic times. Of particular interest are the richly coloured sediments in the region of the islands of Santorini and Milos, in the south Aegean.[2] Notable cities on the Aegean coastline include Athens, Thessaloniki, Volos, Kavala and Heraklion in Greece, and İzmir and Bodrum in Turkey.
+
+A number of issues concerning sovereignty within the Aegean Sea are disputed between Greece and Turkey. The Aegean dispute has had a large effect on Greek-Turkish relations since the 1970s. Issues include the delimitation of territorial waters, national airspace, exclusive economic zones and flight information regions.[3]
+
+Late Latin authors referred the name Aegaeus to Aegeus, whom they said to have jumped into that sea (instead of jumping from the Athenian acropolis, as told by some Greek authors). He was the father of Theseus, the mythical king and founder-hero of Athens. Aegeus had told Theseus to put up white sails when returning if he was successful in killing the Minotaur. When Theseus returned, he forgot these instructions, and Aegeus thinking his son to have died then drowned himself in the sea.[4]
+
+The sea was known in Latin as Aegaeum mare under the control of the Roman Empire. The Venetians, who ruled many Greek islands in the High and Late Middle Ages, popularized the name Archipelago (Greek: αρχιπέλαγος, meaning "main sea" or "chief sea"), a name that held on in many European countries until the early modern period. In the South Slavic languages, the Aegean is called White Sea (Bulgarian: Бяло море/Byalo more; Macedonian: Belo more/Бело море; Serbo-Croatian: Belo more/Бело море).[5] The Turkish name for the sea is Ege Denizi, derived from the Greek name.
+
+The Aegean Sea is an elongated embayment of the Mediterranean Sea, and covers about 214,000 square kilometres (83,000 sq mi) in area, measuring about 670 kilometres (420 mi) longitudinally and 390 kilometres (240 mi) latitudinal. The sea's maximum depth is 3,543 metres (11,624 ft), located at a point east of Crete. The Aegean Islands are found within its waters, with the following islands delimiting the sea on the south, generally from west to east: Kythera, Antikythera, Crete, Kasos, Karpathos and Rhodes. The Anatolian peninsula marks the eastern boundary of the sea, while the Greek mainland marks the west. Several seas are contained within the Aegean Sea; the Thracian Sea is a section of the Aegean located to the north, the Icarian Sea to the east, the Myrtoan Sea to the west, while the Sea of Crete is the southern section.
+
+The Greek regions that border the sea, in alphabetical order, are Attica, Central Greece, Central Macedonia, Crete, Eastern Macedonia and Thrace, North Aegean, Peloponnese, South Aegean, and Thessaly. The historical region of Macedonia also borders the sea, to the north.
+
+The Aegean Islands, which almost all belong to Greece, can be divided into seven groups:
+
+Many of the Aegean islands or island chains, are geographically extensions of the mountains on the mainland. One chain extends across the sea to Chios, another extends across Euboea to Samos, and a third extends across the Peloponnese and Crete to Rhodes, dividing the Aegean from the Mediterranean.
+
+The bays and gulfs of the Aegean beginning at the South and moving clockwise include on Crete, the Mirabello, Almyros, Souda and Chania bays or gulfs, on the mainland the Myrtoan Sea to the west with the Argolic Gulf, the Saronic Gulf northwestward, the Petalies Gulf which connects with the South Euboic Sea, the Pagasetic Gulf which connects with the North Euboic Sea, the Thermian Gulf northwestward, the Chalkidiki Peninsula including the Cassandra and the Singitic Gulfs, northward the Strymonian Gulf and the Gulf of Kavala and the rest are in Turkey; Saros Gulf, Edremit Gulf, Dikili Gulf, Gulf of Çandarlı, Gulf of İzmir, Gulf of Kuşadası, Gulf of Gökova, Güllük Gulf.
+
+The Aegean sea is connected to the Sea of Marmara by the Dardanelles, also known from Classical Antiquity as the Hellespont. The Dardanelles are located to the northeast of the sea. It ultimately connects with the Black Sea through the Bosphoros strait, upon which lies the city of Istanbul. The Dardanelles and the Bosphoros are known as the Turkish Straits.
+
+According to the International Hydrographic Organization, the limits of the Aegean Sea as follows:[8]
+
+Aegean surface water circulates in a counterclockwise gyre, with hypersaline Mediterranean water moving northward along the west coast of Turkey, before being displaced by less dense Black Sea outflow. The dense Mediterranean water sinks below the Black Sea inflow to a depth of 23–30 metres (75–98 ft), then flows through the Dardanelles Strait and into the Sea of Marmara at velocities of 5–15 cm/s (2–6 in/s). The Black Sea outflow moves westward along the northern Aegean Sea, then flows southwards along the east coast of Greece.[9]
+
+The physical oceanography of the Aegean Sea is controlled mainly by the regional climate, the fresh water discharge from major rivers draining southeastern Europe, and the seasonal variations in the Black Sea surface water outflow through the Dardanelles Strait.
+
+Analysis[10] of the Aegean during 1991 and 1992 revealed three distinct water masses:
+
+The climate of the Aegean Sea largely reflects the climate of Greece and Western Turkey, which is to say, predominately Mediterranean. According to the Köppen climate classification, most of the Aegean is classified as Hot-summer Mediterranean (Csa), with hotter and drier summers along with milder and wetter winters. However, high temperatures during summers are generally not quite as high as those in arid or semiarid climates due to the presence of a large body of water. This is most predominant in the west and east coasts of the Aegean, and within the Aegean islands. In the north of the Aegean Sea, the climate is instead classified as Cold semi-arid (BSk), which feature cooler summers than Hot-summer Mediterranean climates.
+The Etesian winds are a dominant weather influence in the Aegean Basin.
+
+The below table lists climate conditions of some major Aegean cities:
+
+Numerous Greek and Turkish settlements are located along their mainland coast, as well as on towns on the Aegean islands. The largest cities are Athens and Thessaloniki in Greece and İzmir in Turkey. The most populated of the Aegean islands is Crete, followed by Euboea and Rhodes.
+
+Athens
+
+
+
+Thessaloniki
+
+İzmir
+
+
+
+Heraklion
+
+Greece has established several marine protected areas along its coasts. According to the Network of Managers of Marine Protected Areas in the Mediterranean (MedPAN), four Greek MPAs are participating in the Network. These include Alonnisos Marine Park, while the Missolonghi–Aitoliko Lagoons and the island of Zakynthosare not on the Aegean.[13]
+
+The current coastline dates back to about 4000 BC. Before that time, at the peak of the last ice age (about 18,000 years ago) sea levels everywhere were 130 metres lower, and there were large well-watered coastal plains instead of much of the northern Aegean. When they were first occupied, the present-day islands including Milos with its important obsidian production were probably still connected to the mainland. The present coastal arrangement appeared around 9,000 years ago, with post-ice age sea levels continuing to rise for another 3,000 years after that.[14]
+
+The subsequent Bronze Age civilizations of Greece and the Aegean Sea have given rise to the general term Aegean civilization. In ancient times, the sea was the birthplace of two ancient civilizations – the Minoans of Crete and the Myceneans of the Peloponnese.[15]
+
+The Minoan civilization was a Bronze Age civilization on the island of Crete and other Aegean islands, flourishing from around 2700 to 1450 BC before a period of decline, finally ending at around 1100 BC. It represented the first advanced civilization in Europe, leaving behind massive building complexes, tools, stunning artwork, writing systems, and a massive network of trade.[16] The Minoan period saw extensive trade between Crete, Aegean, and Mediterranean settlements, particularly the Near East. The most notable Minoan palace is that of Knossos, followed by that of Phaistos.
+
+After the decline of the Minoan civilization, the Mycenaean Greeks arose, becoming the first advanced civilization in mainland Greece, which lasted from approximately 1600 to 1100 BC. It is believed that the site of Mycenae, which sits close to the Aegean coast, was the center of Mycenaean civilization. The Mycenaeans introduced several innovations in the fields of engineering, architecture and military infrastructure, while trade over vast areas of the Mediterranean, including the Aegean, was essential for the Mycenaean economy. Their syllabic script, the Linear B, offers the first written records of the Greek language and their religion already included several deities that can also be found in the Olympic Pantheon. Mycenaean Greece was dominated by a warrior elite society and consisted of a network of palace-centered states that developed rigid hierarchical, political, social and economic systems. At the head of this society was the king, known as wanax.
+
+The civilization of Mycenaean Greeks perished with the collapse of Bronze Age culture in the eastern Mediterranean, to be followed by the so-called Greek Dark Ages. It is undetermined what cause the collapse of the Mycenaeans. During the Greek Dark Ages, writing in the Linear B script ceased, vital trade links were lost, and towns and villages were abandoned.
+
+The Archaic period followed the Greek Dark Ages in the 8th century BC. Greece became divided into small self-governing communities, and adopted the Phoenician alphabet, modifying it to create the Greek alphabet. By the 6th century BC several cities had emerged as dominant in Greek affairs: Athens, Sparta, Corinth, and Thebes, of which Athens, Sparta, and Corinth were closest to the Aegean Sea. Each of them had brought the surrounding rural areas and smaller towns under their control, and Athens and Corinth had become major maritime and mercantile powers as well. In the 8th and 7th centuries BC many Greeks emigrated to form colonies in Magna Graecia (Southern Italy and Sicily), Asia Minor and further afield.
+
+The Aegean Sea would later come to be under the control, albeit briefly, of the Kingdom of Macedonia. Philip II and his son Alexander the Great led a series of conquests that led not only to the unification of the Greek mainland and the control of the Aegean Sea under his rule, but also the destruction of the Achaemenid Empire. After Alexander the Great's death, his empire was divided among his generals. Cassander became king of the Hellenistic kingdom of Macedon, which held territory along the western coast of the Aegean, roughly corresponding to modern-day Greece. The Kingdom of Lysimachus had control over the sea's eastern coast. Greece had entered the Hellenistic period.
+
+The Macedonian Wars were a series of conflicts fought by the Roman Republic and its Greek allies in the eastern Mediterranean against several different major Greek kingdoms. They resulted in Roman control or influence over the eastern Mediterranean basin, including the Aegean, in addition to their hegemony in the western Mediterranean after the Punic Wars. During Roman rule, the land around the Aegean Sea fell under the provinces of Achaea, Macedonia, Thracia, Asia and Creta et Cyrenica (island of Crete)
+
+The Fall of the Western Roman Empire allowed its successor state, the Byzantine Empire, to continue Roman control over the Aegean Sea. However, their territory would later be threatened by the Early Muslim conquests initiated by Muhammad in the 7th century. Although the Rashidun Caliphate did not manage to obtain land along the cost of the Aegean sea, its conquest of the Eastern Anatolian peninsula as well as Egypt, the Levant, and North Africa left the Byzantine Empire weakened. The Umayyad Caliphate expanded the territorial gains of the Rashidun Caliphate, conquering much of North Africa, and threatened the Byzantine Empire's control of Western Anatolia, where it meets the Aegean Sea.
+
+During the 820s, Crete was conquered by a group of Berbers Andalusians exiles led by Abu Hafs Umar al-Iqritishi, and it became an independent Islamic state. The Byzantine Empire launched a campaign that took most of the island back in 842 and 843 under Theoktistos, but the reconquest was not completed and was soon reversed. Later attempts by the Byzantine Empire to recover the island were without success. For the approximately 135 years of its existence, the emirate of Crete was one of the major foes of Byzantium. Crete commanded the sea lanes of the Eastern Mediterranean and functioned as a forward base and haven for Muslim corsair fleets that ravaged the Byzantine-controlled shores of the Aegean Sea. Crete returned to Byzantine rule under Nikephoros Phokas, who launched a huge campaign against the Emirate of Crete in 960 to 961.
+
+Meanwhile, the Bulgarian Empire threatened Byzantine control of Northern Greece and the Aegean coast to the south. Under Presian I and his successor Boris I, the Bulgarian Empire managed to obtain a small portion of the northern Aegean coast. Simeon I of Bulgaria led Bulgaria to its greatest territorial expansion, and managed to conqueror much of the northern and western coasts of the Aegean. The Byzantines later regained control. The Second Bulgarian Empire achieved similar success along, again, the northern and western coasts, under Ivan Asen II of Bulgaria.
+
+The Seljuq Turks, under the Seljuk Empire, invaded the Byzantine Empire in 1068, from which they annexed almost all of Anatolia, including the east coast of the Aegean Sea, during the reign of Alp Arslan, the second Sultan of the Seljuk Empire. After the death of his successor, Malik Shah I, the empire was divided, and Malik Shah was succeeded in Anatolia by Kilij Arslan I, who founded the Sultanate of Rum. The Byzantines yet again recaptured the eastern coast of the Aegean.
+
+After Constantinople was occupied by Western European and Venetian forces during the Fourth Crusade, the area around the Aegean sea was fragmented into multiple entities, including the Latin Empire, the Kingdom of Thessalonica, the Empire of Nicaea, the Principality of Achaea, and the Duchy of Athens. The Venetians created the maritime state of the Duchy of the Archipelago, which included all the Cyclades except Mykonos and Tinos. The Empire of Nicaea, a Byzantine rump state, managed to effect the Recapture of Constantinople from the Latins in 1261 and defeat Epirus. Byzantine successes were not to last; the Ottomans would conquer the area around the Aegean coast, but before their expansion the Byzantine Empire had already been weakened from internal conflict. By the late 14th century the Byzantine Empire had lost all control of the coast of the Aegean Sea and could exercise power around their capital, Constantinople. The Ottoman Empire then gained control of all the Aegean coast with the exception of Crete, which was a Venetian colony until 1669.
+
+The Greek War of Independence allowed a Greek state on the coast of the Aegean from 1829 onward. The Ottoman Empire held a presence over the sea for over 500 years until its dissolution following World War I, when it was replaced by modern Turkey. During the war, Greece gained control over the area around the northern coast of the Aegean. By the 1930s, Greece and Turkey had about resumed their present-day borders.
+
+In the Italo-Turkish War of 1912, Italy captured the Dodecanese islands, and had occupied them since, reneging on the 1919 Venizelos–Tittoni agreement to cede them to Greece. The Greco-Italian War took place from October 1940 to April 1941 as part of the Balkans Campaign of World War II. The Italian war aim was to establish a Greek puppet state, which would permit the Italian annexation of the Sporades and the Cyclades islands in the Aegean Sea, to be administered as a part of the Italian Aegean Islands. The German invasion resulted in the Axis occupation of Greece. The German troops evacuated Athens on 12 October 1944, and by the end of the month, they had withdrawn from mainland Greece. Greece was then liberated by Allied troops.
+
+Many of the islands in the Aegean have safe harbours and bays. In ancient times, navigation through the sea was easier than travelling across the rough terrain of the Greek mainland, and to some extent, the coastal areas of Anatolia. Many of the islands are volcanic, and marble and iron are mined on other islands. The larger islands have some fertile valleys and plains.
+
+Of the main islands in the Aegean Sea, two belong to Turkey – Bozcaada (Tenedos) and Gökçeada (Imbros); the rest belong to Greece. Between the two countries, there are political disputes over several aspects of political control over the Aegean space, including the size of territorial waters, air control and the delimitation of economic rights to the continental shelf. These issues are known as the Aegean dispute.
+
+Multiple ports are located along the Greek and Turkish coasts of the Aegean Sea. The port of Piraeus in Athens is the chief port in Greece, the largest passenger port in Europe[17][18] and the third largest in the world,[19] servicing about 20 million passengers annually. With a throughput of 1.4 million TEUs, Piraeus is placed among the top ten ports in container traffic in Europe and the top container port in the Eastern Mediterranean.[20] Piraeus is also the commercial hub of Greek shipping. Piraeus bi-annually acts as the focus for a major shipping convention, known as Posidonia, which attracts maritime industry professionals from all over the world. Piraeus is currently Greece's third-busiest port in terms of tons of goods transported, behind Aghioi Theodoroi and Thessaloniki.[21] The central port serves ferry routes to almost every island in the eastern portion of Greece, the island of Crete, the Cyclades, the Dodecanese, and much of the northern and the eastern Aegean Sea, while the western part of the port is used for cargo services.
+
+As of 2007, the Port of Thessaloniki was the second-largest container port in Greece after the port of Piraeus, making it one of the busiest ports in Greece. In 2007, the Port of Thessaloniki handled 14,373,245 tonnes of cargo and 222,824 TEU's. Paloukia, on the island of Salamis, is a major passenger port.
+
+Fish are Greece's second largest agricultural export, and Greece has Europe's largest fishing fleet.[22]  Fish captured include sardines, mackerel, grouper, grey mullets, sea bass, and seabream. There is a considerable difference between fish catches between the pelagic and demersal zones;[23] with respect to pelagic fisheries, the catches from the northern, central and southern Aegean area groupings are dominated, respectively, by anchovy, horse mackerels, and boops. For demersal fisheries, the catches from the northern and southern Aegean area groupings are dominated by grey mullets and pickerel (Spicara smaris) respectively.
+
+The industry has been impacted by the Great Recession.[clarification needed] Overfishing and habitat destruction is also a concern, threatening grouper, and seabream populations, resulting in perhaps a 50% decline of fish catch.[24] To address these concerns, Greek fishermen have been offered a compensation by the government. Although some species are defined as protected or threatened under EU legislation, several illegal species such as the molluscs Pinna nobilis, Charonia tritonis and Lithophaga lithophaga, can be bought in restaurants and fish markets around Greece.[25]
+
+The Aegean islands within the Aegean Sea are significant tourist destinations. Tourism to the Aegean islands contributes a significant portion of tourism in Greece, especially since the second half of the 20th century.[26] A total of five UNESCO World Heritage sites are located the Aegean Islands; these include the Monastery of Saint John the Theologian and the Cave of the Apocalypse on Patmos,[27] the Pythagoreion and Heraion of Samos in Samos,[28] the Nea Moni of Chios,[29] the island of Delos,[30] and the Medieval City of Rhodes.[31]
+
+Greece is one of the most visited countries in Europe and the world with over 33 million visitors in 2018,[32] and the tourism industry around a quarter of Greece's Gross Domestic Product.[33] The islands of Santorini, Crete, Lesbos, Delos, and Mykonos are common tourist destinations. An estimated 2 million tourists visit Santorini annually.[34] However, concerns relating to overtourism have arisen in recent years, such as issues of inadequate infrastructure and overcrowding.[35] Alongside Greece, Turkey has also been successful in developing resort areas and attracting large number of tourists,[36] contributing to tourism in Turkey. The phrase "Blue Cruise" refers to recreational voyages along the Turkish Riviera, including across the Aegean.[37] The ancient city of Troy, a World Heritage Site, is on the Turkish coast of the Aegean.[38]
+
+Greece and Turkey both take part in the Blue Flag beach certification programme of the Foundation for Environmental Education. The certification is awarded for beaches and marinas meeting strict quality standards including environmental protection, water quality, safety and services criteria.[39] As of 2015, the Blue Flag has been awarded to 395 beaches and 9 marinas in Greece. Southern Aegean beaches on the Turkish coast include Muğla, with 102 beaches awarded with the blue flag, along with İzmir and Aydın, who have 49 and 30 beaches awarded respectively.[40]

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+A parent  is a caregiver of the offspring in their own species. In humans, a parent is the caretaker of a child (where "child" refers to offspring, not necessarily age). A biological parent is a person whose gamete resulted in a child, a male through the sperm, and a female through the ovum. Biological parents are first-degree relatives and have 50% genetic meet. A female can also become a parent through surrogacy. Some parents may be adoptive parents, who nurture and raise an offspring, but are not biologically related to the child. Orphans without adoptive parents can be raised by their grandparents or other family members.
+
+A parent can also be elaborated as an ancestor removed one generation. With recent medical advances, it is possible to have more than two biological parents.[1][2][3] Examples of third biological parents include instances involving surrogacy or a third person who has provided DNA samples during an assisted reproductive procedure that has altered the recipients' genetic material.[4]
+
+The most common types of parents are mothers, fathers, step-parents, and grandparents. A mother is, "a woman in relation to a child or children to whom she has given birth."[5] The extent to which it is socially acceptable for a parent to be involved in their offspring's life varies from culture to culture, however one that exhibits too little involvement is sometimes said to exhibit child neglect,[6] while one that is too involved is sometimes said to be overprotective, cosseting, nosey, or intrusive.[7]
+
+An individual's biological parents are the persons from whom the individual inherits his or her genes. The term is generally only used if there is a need to distinguish an individual's parents from their biological parents,  For example, an individual whose father has remarried may call the father's new wife their stepmother and continue to refer to their mother normally, though someone who has had little or no contact with their biological mother may address their foster parent as their mother, and their biological mother as such, or perhaps by her first name.,[citation needed]
+
+A mother is a female who has a maternal connection with another individual, whether arising from conception, by giving birth to, or raising the individual in the role of a parent.[8] More than one female may have such connections with an individual. Because of the complexity and differences of a mother's social, cultural, and religious definitions and roles, it is challenging to define a mother to suit a universally accepted definition. The utilization of a surrogate mother may result in explication of there being two biological mothers.[9]
+
+A father is a male parent of any type of offspring.[10] It may be the person who shares in the raising of a child or who has provided the biological material, the sperm, which results in the birth of the child.
+
+Grandparents are the parents of a person's own parent, whether that be a father or a mother. Every sexually reproducing creature who is not a genetic chimera has a maximum of four genetic grandparents, eight genetic great-grandparents, sixteen genetic great-great-grandparents and so on. Rarely, such as in the case of sibling or half-sibling incest, these numbers are lower.
+
+A paternity test is conducted to prove paternity, that is, whether a male is the biological father of another individual. This may be relevant in view of rights and duties of the father. Similarly, a maternity test can be carried out. This is less common, because at least during childbirth and pregnancy, except in the case of a pregnancy involving embryo transfer or egg donation, it is obvious who the mother is. However, it is used in a number of events such as legal battles where a person's maternity is challenged, where the mother is uncertain because she has not seen her child for an extended period of time, or where deceased persons need to be identified.
+
+Although not constituting completely reliable evidence, several congenital traits such as attached earlobes, the widow's peak, or the cleft chin, may serve as tentative indicators of (non-) parenthood as they are readily observable and inherited via autosomal-dominant genes.
+
+A more reliable way to ascertain parenthood is via DNA analysis (known as genetic fingerprinting of individuals, although older methods have included ABO blood group typing, analysis of various other proteins and enzymes, or using human leukocyte antigens. The current techniques for paternity testing are using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). For the most part, however, genetic fingerprinting has all but taken over all the other forms of testing.
+
+A legal guardian is a person who has the legal authority (and the corresponding duty) to care for the personal and property interests of another person, called a ward. Guardians are typically used in three situations: guardianship for an incapacitated senior (due to old age or infirmity), guardianship for a minor, and guardianship for developmentally disabled adults.
+
+Most countries and states have laws that provide that the parents of a minor child are the legal guardians of that child, and that the parents can designate who shall become the child's legal guardian in the event of death, subject to the approval of the court. Some jurisdictions allow a parent of a child to exercise the authority of a legal guardian without a formal court appointment. In such circumstances the parent acting in that capacity is called the natural guardian of that parent's child.
+
+Parenting or child rearing is the process of promoting and supporting the physical, emotional, social, financial, and intellectual development of a child from infancy to adulthood. Parenting refers to the aspects of raising a child aside from the biological relationship.[11]
+
+A child has at least one biological father and at least one biological mother, but not every family is a traditional nuclear family. There are many variants, such as adoption, shared parenting, stepfamilies, and LGBT parenting, over which there has been controversy.
+
+The social science literature rejects the notion that there is an optimal gender mix of parents or that children and adolescents with same-sex parents suffer any developmental disadvantages compared with those with two opposite-sex parents.[12][13] The professionals and the major associations now agree there is a well-established and accepted consensus in the field that there is no optimal gender combination of parents.[14] The family studies literature indicates that it is family processes (such as the quality of parenting and relationships within the family) that contribute to determining children's well-being and "outcomes," rather than family structures, per se, such as the number, gender, sexuality and co-habitation status of parents.[13]
+
+An offspring who hates their father is called a misopater, one that hates their mother is a misomater, while a parent that hates their offspring is a misopedist.[15][16] Parent–offspring conflict describes the evolutionary conflict arising from differences in optimal fitness of parents and their offspring. While parents tend to maximize the number of offspring, the offspring can increase their fitness by getting a greater share of parental investment often by competing with their siblings. The theory was proposed by Robert Trivers in 1974 and extends the more general selfish gene theory and has been used to explain many observed biological phenomena.[17] For example, in some bird species, although parents often lay two eggs and attempt to raise two or more young, the strongest fledgling takes a greater share of the food brought by parents and will often kill the weaker sibling, an act known as siblicide.
+
+David Haig has argued that human fetal genes would be selected to draw more resources from the mother than it would be optimal for the mother to give, a hypothesis that has received empirical support. The placenta, for example, secretes allocrine hormones that decrease the sensitivity of the mother to insulin and thus make a larger supply of blood sugar available to the fetus. The mother responds by increasing the level of insulin in her bloodstream, the placenta has insulin receptors that stimulate the production of insulin-degrading enzymes which counteract this effect.[18]
+
+In Europe, parents are generally happier than non-parents. In women, happiness increases after the first child, but having higher-order children is not associated with further increased well-being. Happiness seems to increase most in the year before and after the first childbirth.[19]

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+
+
+The sea, the world ocean, or simply the ocean is the connected body of salty water that covers over 70% of Earth's surface (361,132,000 square kilometres (139,434,000 sq mi), with a total volume of roughly 1,332,000,000 cubic kilometres (320,000,000 cu mi)).[1] It moderates Earth's climate and has important roles in the water cycle, carbon cycle, and nitrogen cycle. It has been travelled and explored since ancient times, while the scientific study of the sea—oceanography—dates broadly from the voyages of Captain James Cook to explore the Pacific Ocean between 1768 and 1779. The word sea is also used to denote smaller, partly landlocked sections of the ocean and certain large, entirely landlocked, saltwater lakes, such as the Caspian Sea and the Dead Sea.
+
+The most abundant solid dissolved in seawater is sodium chloride. The water also contains salts of magnesium, calcium, and potassium, amongst many other elements, some in minute concentrations. Salinity varies widely, being lower near the surface and the mouths of large rivers and higher in the depths of the ocean; however, the relative proportions of dissolved salts varies little across the oceans. Winds blowing over the surface of the sea produce waves, which break when they enter shallow water. Winds also create surface currents through friction, setting up slow but stable circulations of water throughout the oceans. The directions of the circulation are governed by factors including the shapes of the continents and Earth's rotation (the Coriolis effect). Deep-sea currents, known as the global conveyor belt, carry cold water from near the poles to every ocean. Tides, the generally twice-daily rise and fall of sea levels, are caused by Earth's rotation and the gravitational effects of the orbiting Moon and, to a lesser extent, of the Sun. Tides may have a very high range in bays or estuaries. Submarine earthquakes arising from tectonic plate movements under the oceans can lead to destructive tsunamis, as can volcanoes, huge landslides or the impact of large meteorites.
+
+A wide variety of organisms, including bacteria, protists, algae, plants, fungi, and animals, live in the sea, which offers a wide range of marine habitats and ecosystems, ranging vertically from the sunlit surface and shoreline to the great depths and pressures of the cold, dark abyssal zone, and in latitude from the cold waters under polar ice caps to the colourful diversity of coral reefs in tropical regions. Many of the major groups of organisms evolved in the sea and life may have started there.
+
+The sea provides substantial supplies of food for humans, mainly fish, but also shellfish, mammals and seaweed, whether caught by fishermen or farmed underwater. Other human uses of the sea include trade, travel, mineral extraction, power generation, warfare, and leisure activities such as swimming, sailing, and scuba diving. Many of these activities create marine pollution. The sea is important in human culture, with major appearances in literature at least since Homer's Odyssey, in marine art, in cinema, in theatre and in classical music. Symbolically, the sea appears as monsters such as Scylla in mythology and represents the unconscious mind in dream interpretation.
+
+The sea is the interconnected system of all the Earth's oceanic waters, including the Atlantic, Pacific, Indian, Southern and Arctic Oceans.[2] However, the word "sea" can also be used for many specific, much smaller bodies of seawater, such as the North Sea or the Red Sea. There is no sharp distinction between seas and oceans, though generally seas are smaller, and are often partly (as marginal seas) or wholly (as inland seas) bordered by land.[3] However, the Sargasso Sea has no coastline and lies within a circular current, the North Atlantic Gyre.[4](p90) Seas are generally larger than lakes and contain salt water, but the Sea of Galilee is a freshwater lake.[5][a] The United Nations Convention on the Law of the Sea states that all of the ocean is "sea".[9][10][b]
+
+Earth is the only known planet with seas of liquid water on its surface,[4](p22) although Mars possesses ice caps and similar planets in other solar systems may have oceans.[12] Earth's 1,335,000,000 cubic kilometers (320,000,000 cu mi) of sea contain about 97.2 percent of its known water[13][c] and cover more than 70 percent of its surface.[4](p7) Another 2.15% of Earth's water is frozen, found in the sea ice covering the Arctic Ocean, the ice cap covering Antarctica and its adjacent seas, and various glaciers and surface deposits around the world. The remainder (about 0.65% of the whole) form underground reservoirs or various stages of the water cycle, containing the freshwater encountered and used by most terrestrial life: vapor in the air, the clouds it slowly forms, the rain falling from them, and the lakes and rivers spontaneously formed as its waters flow again and again to the sea.[13]
+
+The scientific study of water and Earth's water cycle is hydrology; hydrodynamics studies the physics of water in motion. The more recent study of the sea in particular is oceanography. This began as the study of the shape of the ocean's currents[18] but has since expanded into a large and multidisciplinary field:[19] it examines the properties of seawater; studies waves, tides, and currents; charts coastlines and maps the seabeds; and studies marine life.[20] The subfield dealing with the sea's motion, its forces, and the forces acting upon it is known as physical oceanography.[21] Marine biology (biological oceanography) studies the plants, animals, and other organisms inhabiting marine ecosystems. Both are informed by chemical oceanography, which studies the behavior of elements and molecules within the oceans: particularly, at the moment, the ocean's role in the carbon cycle and carbon dioxide's role in the increasing acidification of seawater. Marine and maritime geography charts the shape and shaping of the sea, while marine geology (geological oceanography) has provided evidence of continental drift and the composition and structure of the Earth, clarified the process of sedimentation, and assisted the study of volcanism and earthquakes.[19]
+
+The water in the sea was thought to come from the Earth's volcanoes, starting 4 billion years ago, released by degassing from molten rock.[4](pp24–25) More recent work suggests much of the Earth's water may come from comets.[22] A characteristic of seawater is that it is salty. Salinity is usually measured in parts per thousand (‰ or per mil), and the open ocean has about 35 grams (1.2 oz) solids per litre, a salinity of 35 ‰. The Mediterranean Sea is slightly higher at 38 ‰,[23] while the salinity of the northern Red Sea can reach 41‰.[24] In contrast, some landlocked hypersaline lakes have a much higher salinity, for example the Dead Sea has 300 grams (11 oz) dissolved solids per litre (300 ‰).
+
+While the constituents of table salt sodium and chloride make up about 85 percent of the solids in solution, there are also other metal ions such as magnesium and calcium, and negative ions including sulphate, carbonate, and bromide. Despite variations in the levels of salinity in different seas, the relative composition of the dissolved salts is stable throughout the world's oceans.[25][26] Seawater is too saline for humans to drink safely, as the kidneys cannot excrete urine as salty as seawater.[27]
+
+Although the amount of salt in the ocean remains relatively constant within the scale of millions of years, various factors affect the salinity of a body of water.[28] Evaporation and by-product of ice formation (known as "brine rejection") increase salinity, whereas precipitation, sea ice melt, and runoff from land reduce it.[28] The Baltic Sea, for example, has many rivers flowing into it, and thus the sea could be considered as brackish.[29] Meanwhile, the Red Sea is very salty due to its high evaporation rate.[30]
+
+Sea temperature depends on the amount of solar radiation falling on its surface. In the tropics, with the sun nearly overhead, the temperature of the surface layers can rise to over 30 °C (86 °F) while near the poles the temperature in equilibrium with the sea ice is about −2 °C (28 °F). There is a continuous circulation of water in the oceans. Warm surface currents cool as they move away from the tropics, and the water becomes denser and sinks. The cold water moves back towards the equator as a deep sea current, driven by changes in the temperature and density of the water, before eventually welling up again towards the surface. Deep seawater has a temperature between −2 °C (28 °F) and 5 °C (41 °F) in all parts of the globe.[31]
+
+Seawater with a typical salinity of 35‰ has a freezing point of about −1.8 °C (28.8 °F).[32] When its temperature becomes low enough, ice crystals form on the surface. These break into small pieces and coalesce into flat discs that form a thick suspension known as frazil. In calm conditions this freezes into a thin flat sheet known as nilas, which thickens as new ice forms on its underside. In more turbulent seas, frazil crystals join together into flat discs known as pancakes. These slide under each other and coalesce to form floes. In the process of freezing, salt water and air are trapped between the ice crystals. Nilas may have a salinity of 12–15 ‰, but by the time the sea ice is one year old, this falls to 4–6 ‰.[33]
+
+The amount of oxygen found in seawater depends primarily on the plants growing in it. These are mainly algae, including phytoplankton, with some vascular plants such as seagrasses. In daylight the photosynthetic activity of these plants produces oxygen, which dissolves in the seawater and is used by marine animals. At night, photosynthesis stops, and the amount of dissolved oxygen declines. In the deep sea, where insufficient light penetrates for plants to grow, there is very little dissolved oxygen. In its absence, organic material is broken down by anaerobic bacteria producing hydrogen sulphide.[34] Global warming is likely to reduce levels of oxygen in surface waters, since the solubility of oxygen in water falls at higher temperatures.[35]
+The amount of light that penetrates the sea depends on the angle of the sun, the weather conditions and the turbidity of the water. Much light gets reflected at the surface, and red light gets absorbed in the top few metres. Yellow and green light reach greater depths, and blue and violet light may penetrate as deep as 1,000 metres (3,300 ft). There is insufficient light for photosynthesis and plant growth beyond a depth of about 200 metres (660 ft).[36]
+
+Wind blowing over the surface of a body of water forms waves that are perpendicular to the direction of the wind. The friction between air and water caused by a gentle breeze on a pond causes ripples to form. A strong blow over the ocean causes larger waves as the moving air pushes against the raised ridges of water. The waves reach their maximum height when the rate at which they are travelling nearly matches the speed of the wind. In open water, when the wind blows continuously as happens in the Southern Hemisphere in the Roaring Forties, long, organised masses of water called swell roll across the ocean.[4](pp83–84)[37][38][d] If the wind dies down, the wave formation is reduced, but already-formed waves continue to travel in their original direction until they meet land. The size of the waves depends on the fetch, the distance that the wind has blown over the water and the strength and duration of that wind. When waves meet others coming from different directions, interference between the two can produce broken, irregular seas.[37] Constructive interference can cause individual (unexpected) rogue waves much higher than normal.[39] Most waves are less than 3 m (10 ft) high[39] and it is not unusual for strong storms to double or triple that height;[40] offshore construction such as wind farms and oil platforms use metocean statistics from measurements in computing the wave forces (due to for instance the hundred-year wave) they are designed against.[41] Rogue waves, however, have been documented at heights above 25 meters (82 ft).[42][43]
+
+The top of a wave is known as the crest, the lowest point between waves is the trough and the distance between the crests is the wavelength. The wave is pushed across the surface of the sea by the wind, but this represents a transfer of energy and not a horizontal movement of water. As waves approach land and move into shallow water, they change their behavior. If approaching at an angle, waves may bend (refraction) or wrap rocks and headlands (diffraction). When the wave reaches a point where its deepest oscillations of the water contact the seabed, they begin to slow down. This pulls the crests closer together and increases the waves' height, which is called wave shoaling. When the ratio of the wave's height to the water depth increases above a certain limit, it "breaks", toppling over in a mass of foaming water.[39] This rushes in a sheet up the beach before retreating into the sea under the influence of gravity.[37]
+
+A tsunami is an unusual form of wave caused by an infrequent powerful event such as an underwater earthquake or landslide, a meteorite impact, a volcanic eruption or a collapse of land into the sea. These events can temporarily lift or lower the surface of the sea in the affected area, usually by a few feet. The potential energy of the displaced seawater is turned into kinetic energy, creating a shallow wave, a tsunami, radiating outwards at a velocity proportional to the square root of the depth of the water and which therefore travels much faster in the open ocean than on a continental shelf.[44] In the deep open sea, tsunamis have wavelengths of around 80 to 300 miles (130 to 480 km), travel at speeds of over 600 miles per hour (970 km/hr)[45] and usually have a height of less than three feet, so they often pass unnoticed at this stage.[46] In contrast, ocean surface waves caused by winds have wavelengths of a few hundred feet, travel at up to 65 miles per hour (105 km/h) and are up to 45 feet (14 metres) high.[46]
+
+A trigger event on the continental shelf may cause a local tsunami on the land side and a distant tsunami that travels out across the ocean. The energy of the wave is dissipated only gradually, but is spread out over the wave front, so as the wave radiates away from the source, the front gets longer and the average energy reduces, so distant shores will, on average, be hit by weaker waves. However, as the speed of the wave is controlled by the water depth, it does not travel at the same speed in all directions, and this affects the direction of the wave front – an effect known as refraction – which can focus the strength of the advancing tsunami on some areas and weaken it in others according to undersea topography.[47][48]
+
+As a tsunami moves into shallower water its speed decreases, its wavelength shortens and its amplitude increases enormously,[46] behaving in the same way as a wind-generated wave in shallow water, but on a vastly greater scale. Either the trough or the crest of a tsunami can arrive at the coast first.[44] In the former case, the sea draws back and leaves subtidal areas close to the shore exposed which provides a useful warning for people on land.[49] When the crest arrives, it does not usually break but rushes inland, flooding all in its path. Much of the destruction may be caused by the flood water draining back into the sea after the tsunami has struck, dragging debris and people with it. Often several tsunami are caused by a single geological event and arrive at intervals of between eight minutes and two hours. The first wave to arrive on shore may not be the biggest or most destructive.[44] Occasionally, a tsunami may transform into a bore, typically in a shallow bay or an estuary.[45]
+
+Wind blowing over the surface of the sea causes friction at the interface between air and sea. Not only does this cause waves to form but it also makes the surface seawater move in the same direction as the wind. Although winds are variable, in any one place they predominantly blow from a single direction and thus a surface current can be formed. Westerly winds are most frequent in the mid-latitudes while easterlies dominate the tropics.[50] When water moves in this way, other water flows in to fill the gap and a circular movement of surface currents known as a gyre is formed. There are five main gyres in the world's oceans: two in the Pacific, two in the Atlantic and one in the Indian Ocean. Other smaller gyres are found in lesser seas and a single gyre flows around Antarctica. These gyres have followed the same routes for millennia, guided by the topography of the land, the wind direction and the Coriolis effect. The surface currents flow in a clockwise direction in the Northern Hemisphere and anticlockwise in the Southern Hemisphere. The water moving away from the equator is warm, and that flowing in the reverse direction has lost most of its heat. These currents tend to moderate the Earth's climate, cooling the equatorial region and warming regions at higher latitudes.[51] Global climate and weather forecasts are powerfully affected by the world ocean, so global climate modelling makes use of ocean circulation models as well as models of other major components such as the atmosphere, land surfaces, aerosols and sea ice.[52] Ocean models make use of a branch of physics, geophysical fluid dynamics, that describes the large-scale flow of fluids such as seawater.[53]
+
+Surface currents only affect the top few hundred metres (yards) of the sea, but there are also large-scale flows in the ocean depths caused by the movement of deep water masses. A main deep ocean current flows through all the world's oceans and is known as the thermohaline circulation or global conveyor belt. This movement is slow and is driven by differences in density of the water caused by variations in salinity and temperature.[54] At high latitudes the water is chilled by the low atmospheric temperature and becomes saltier as sea ice crystallizes out. Both these factors make it denser, and the water sinks. From the deep sea near Greenland, such water flows southwards between the continental landmasses on either side of the Atlantic. When it reaches the Antarctic, it is joined by further masses of cold, sinking water and flows eastwards. It then splits into two streams that move northwards into the Indian and Pacific Oceans. Here it is gradually warmed, becomes less dense, rises towards the surface and loops back on itself. It takes a thousand years for this circulation pattern to be completed.[51]
+
+Besides gyres, there are temporary surface currents that occur under specific conditions. When waves meet a shore at an angle, a longshore current is created as water is pushed along parallel to the coastline. The water swirls up onto the beach at right angles to the approaching waves but drains away straight down the slope under the effect of gravity. The larger the breaking waves, the longer the beach and the more oblique the wave approach, the stronger is the longshore current.[55] These currents can shift great volumes of sand or pebbles, create spits and make beaches disappear and water channels silt up.[51] A rip current can occur when water piles up near the shore from advancing waves and is funnelled out to sea through a channel in the seabed. It may occur at a gap in a sandbar or near a man-made structure such as a groyne. These strong currents can have a velocity of 3 ft (0.9 m) per second, can form at different places at different stages of the tide and can carry away unwary bathers.[56] Temporary upwelling currents occur when the wind pushes water away from the land and deeper water rises to replace it. This cold water is often rich in nutrients and creates blooms of phytoplankton and a great increase in the productivity of the sea.[51]
+
+Tides are the regular rise and fall in water level experienced by seas and oceans in response to the gravitational influences of the Moon and the Sun, and the effects of the Earth's rotation. During each tidal cycle, at any given place the water rises to a maximum height known as "high tide" before ebbing away again to the minimum "low tide" level. As the water recedes, it uncovers more and more of the foreshore, also known as the intertidal zone. The difference in height between the high tide and low tide is known as the tidal range or tidal amplitude.[57][58]
+
+Most places experience two high tides each day, occurring at intervals of about 12 hours and 25 minutes. This is half the 24 hours and 50 minute period that it takes for the Earth to make a complete revolution and return the Moon to its previous position relative to an observer. The Moon's mass is some 27 million times smaller than the Sun, but it is 400 times closer to the Earth.[59] Tidal force or tide-raising force decreases rapidly with distance, so the moon has more than twice as great an effect on tides as the Sun.[59] A bulge is formed in the ocean at the place where the Earth is closest to the Moon, because it is also where the effect of the Moon's gravity is stronger. On the opposite side of the Earth, the lunar force is at its weakest and this causes another bulge to form. As the Moon rotates around the Earth, so do these ocean bulges move around the Earth. The gravitational attraction of the Sun is also working on the seas, but its effect on tides is less powerful than that of the Moon, and when the Sun, Moon and Earth are all aligned (full moon and new moon), the combined effect results in the high "spring tides". In contrast, when the Sun is at 90° from the Moon as viewed from Earth, the combined gravitational effect on tides is less causing the lower "neap tides".[57]
+
+Tidal flows of seawater are resisted by the water's inertia and can be affected by land masses. In places like the Gulf of Mexico where land constrains the movement of the bulges, only one set of tides may occur each day. Inshore from an island there may be a complex daily cycle with four high tides. The island straits at Chalkis on Euboea experience strong currents which abruptly switch direction, generally four times per day but up to 12 times per day when the moon and the sun are 90 degrees apart.[60] Where there is a funnel-shaped bay or estuary, the tidal range can be magnified. The Bay of Fundy is the classic example of this and can experience spring tides of 15 m (49 ft). Although tides are regular and predictable, the height of high tides can be lowered by offshore winds and raised by onshore winds. The high pressure at the centre of an anticyclones pushes down on the water and is associated with abnormally low tides while low-pressure areas may cause extremely high tides.[57] A storm surge can occur when high winds pile water up against the coast in a shallow area and this, coupled with a low pressure system, can raise the surface of the sea at high tide dramatically. In 1900, Galveston, Texas experienced a 15 ft (5 m) surge during a hurricane that overwhelmed the city, killing over 3,500 people and destroying 3,636 homes.[61]
+
+The Earth is composed of a magnetic central core, a mostly liquid mantle and a hard rigid outer shell (or lithosphere), which is composed of the Earth's rocky crust and the deeper mostly solid outer layer of the mantle. On land the crust is known as the continental crust while under the sea it is known as the oceanic crust. The latter is composed of relatively dense basalt and is some five to ten kilometres (three to six miles) thick. The relatively thin lithosphere floats on the weaker and hotter mantle below and is fractured into a number of tectonic plates.[62] In mid-ocean, magma is constantly being thrust through the seabed between adjoining plates to form mid-oceanic ridges and here convection currents within the mantle tend to drive the two plates apart. Parallel to these ridges and nearer the coasts, one oceanic plate may slide beneath another oceanic plate in a process known as subduction. Deep trenches are formed here and the process is accompanied by friction as the plates grind together. The movement proceeds in jerks which cause earthquakes, heat is produced and magma is forced up creating underwater mountains, some of which may form chains of volcanic islands near to deep trenches. Near some of the boundaries between the land and sea, the slightly denser oceanic plates slide beneath the continental plates and more subduction trenches are formed. As they grate together, the continental plates are deformed and buckle causing mountain building and seismic activity.[63][64]
+
+The Earth's deepest trench is the Mariana Trench which extends for about 2,500 kilometres (1,600 mi) across the seabed. It is near the Mariana Islands, a volcanic archipelago in the West Pacific, and though it averages just 68 kilometres (42 mi) wide, its deepest point is 10.994 kilometres (nearly 7 miles) below the surface of the sea.[65] An even longer trench runs alongside the coast of Peru and Chile, reaching a depth of 8,065 metres (26,460 ft) and extending for approximately 5,900 kilometres (3,700 mi). It occurs where the oceanic Nazca Plate slides under the continental South American Plate and is associated with the upthrust and volcanic activity of the Andes.[66]
+
+The zone where land meets sea is known as the coast and the part between the lowest spring tides and the upper limit reached by splashing waves is the shore. A beach is the accumulation of sand or shingle on the shore.[67] A headland is a point of land jutting out into the sea and a larger promontory is known as a cape. The indentation of a coastline, especially between two headlands, is a bay, a small bay with a narrow inlet is a cove and a large bay may be referred to as a gulf.[68] Coastlines are influenced by a number of factors including the strength of the waves arriving on the shore, the gradient of the land margin, the composition and hardness of the coastal rock, the inclination of the off-shore slope and the changes of the level of the land due to local uplift or submergence. Normally, waves roll towards the shore at the rate of six to eight per minute and these are known as constructive waves as they tend to move material up the beach and have little erosive effect. Storm waves arrive on shore in rapid succession and are known as destructive waves as the swash moves beach material seawards. Under their influence, the sand and shingle on the beach is ground together and abraded. Around high tide, the power of a storm wave impacting on the foot of a cliff has a shattering effect as air in cracks and crevices is compressed and then expands rapidly with release of pressure. At the same time, sand and pebbles have an erosive effect as they are thrown against the rocks. This tends to undercut the cliff, and normal weathering processes such as the action of frost follows, causing further destruction. Gradually, a wave-cut platform develops at the foot of the cliff and this has a protective effect, reducing further wave-erosion.[67]
+
+Material worn from the margins of the land eventually ends up in the sea. Here it is subject to attrition as currents flowing parallel to the coast scour out channels and transport sand and pebbles away from their place of origin. Sediment carried to the sea by rivers settles on the seabed causing deltas to form in estuaries. All these materials move back and forth under the influence of waves, tides and currents.[67] Dredging removes material and deepens channels but may have unexpected effects elsewhere on the coastline. Governments make efforts to prevent flooding of the land by the building of breakwaters, seawalls, dykes and levees and other sea defences. For instance, the Thames Barrier is designed to protect London from a storm surge,[69] while the failure of the dykes and levees around New Orleans during Hurricane Katrina created a humanitarian crisis in the United States. Land reclamation in Hong Kong also permitted the construction of Hong Kong International Airport through the leveling and expansion of two smaller islands.[70]
+
+Over most of geologic time, the sea level has been higher than it is today.[4](p74) The main factor affecting sea level over time is the result of changes in the oceanic crust, with a downward trend expected to continue in the very long term.[71] At the last glacial maximum, some 20,000 years ago, the sea level was 120 metres (390 ft) below its present-day level. For at least the last 100 years, sea level has been rising at an average rate of about 1.8 millimetres (0.071 in) per year.[72] Most of this rise can be attributed to an increase in the temperature of the sea and the resulting slight thermal expansion of the upper 500 metres (1,600 ft) of water. Additional contributions, as much as one quarter of the total, come from water sources on land, such as melting snow and glaciers and extraction of groundwater for irrigation and other agricultural and human needs.[73] The rising trend from global warming is expected to continue until at least the end of the 21st century.[74]
+
+The sea plays a part in the water or hydrological cycle, in which water evaporates from the ocean, travels through the atmosphere as vapour, condenses, falls as rain or snow, thereby sustaining life on land, and largely returns to the sea.[75] Even in the Atacama Desert, where little rain ever falls, dense clouds of fog known as the camanchaca blow in from the sea and support plant life.[76]
+
+In central Asia and other large land masses, there are endorheic basins which have no outlet to the sea, separated from the ocean by mountains or other natural geologic features that prevent the water draining away. The Caspian Sea is the largest one of these. Its main inflow is from the River Volga, there is no outflow and the evaporation of water makes it saline as dissolved minerals accumulate. The Aral Sea in Kazakhstan and Uzbekistan, and Pyramid Lake in the western United States are further examples of large, inland saline water-bodies without drainage. Some endorheic lakes are less salty, but all are sensitive to variations in the quality of the inflowing water.[77]
+
+Oceans contain the greatest quantity of actively cycled carbon in the world and are second only to the lithosphere in the amount of carbon they store.[78] The oceans' surface layer holds large amounts of dissolved organic carbon that is exchanged rapidly with the atmosphere. The deep layer's concentration of dissolved inorganic carbon is about 15 percent higher than that of the surface layer[79] and it remains there for much longer periods of time.[80] Thermohaline circulation exchanges carbon between these two layers.[78]
+
+Carbon enters the ocean as atmospheric carbon dioxide dissolves in the surface layers and is converted into carbonic acid, carbonate, and bicarbonate:[81]
+
+It can also enter through rivers as dissolved organic carbon and is converted by photosynthetic organisms into organic carbon. This can either be exchanged throughout the food chain or precipitated into the deeper, more carbon rich layers as dead soft tissue or in shells and bones as calcium carbonate. It circulates in this layer for long periods of time before either being deposited as sediment or being returned to surface waters through thermohaline circulation.[80]
+
+Seawater is slightly alkaline and had an average pH of about 8.2 over the past 300 million years.[82] More recently, anthropogenic activities have steadily increased the carbon dioxide content of the atmosphere; about 30–40% of the added CO2 is absorbed by the oceans, forming carbonic acid and lowering the pH (now below 8.1[82]) through a process called ocean acidification.[83][84][85] The pH is expected to reach 7.7 (representing a 3-fold increase in hydrogen ion concentration) by the year 2100, which is a significant change in a century.[86][e]
+
+One important element for the formation of skeletal material in marine animals is calcium, but calcium carbonate becomes more soluble with pressure, so carbonate shells and skeletons dissolve below its compensation depth.[88] Calcium carbonate also becomes more soluble at lower pH, so ocean acidification is likely to have profound effects on marine organisms with calcareous shells, such as oysters, clams, sea urchins, and corals,[89] because their ability to form shells will be reduced,[90] and the carbonate compensation depth will rise closer to the sea surface. Affected planktonic organisms will include the snail-like molluscs known as pteropods, and single-celled algae called coccolithophorids and foraminifera. All of these are important parts of the food chain and a diminution in their numbers will have significant consequences. In tropical regions, corals are likely to be severely affected as it becomes more difficult to build their calcium carbonate skeletons,[91] in turn adversely impacting other reef dwellers.[86]
+
+The current rate of ocean chemistry change appears to be without precedent in Earth's geological history, making it unclear how well marine ecosystems will be able to adapt to the shifting conditions of the near future.[92] Of particular concern is the manner in which the combination of acidification with the expected additional stressors of higher temperatures and lower oxygen levels will impact the seas.[93]
+
+The oceans are home to a diverse collection of life forms that use it as a habitat. Since sunlight illuminates only the upper layers, the major part of the ocean exists in permanent darkness. As the different depth and temperature zones each provide habitat for a unique set of species, the marine environment as a whole encompasses an immense diversity of life.[94] Marine habitats range from surface water to the deepest oceanic trenches, including coral reefs, kelp forests, seagrass meadows, tidepools, muddy, sandy and rocky seabeds, and the open pelagic zone. The organisms living in the sea range from whales 30 metres (100 ft) long to microscopic phytoplankton and zooplankton, fungi, and bacteria. Marine life plays an important part in the carbon cycle as photosynthetic organisms convert dissolved carbon dioxide into organic carbon and it is economically important to humans for providing fish for use as food.[95][96](pp204–229)
+
+Life may have originated in the sea and all the major groups of animals are represented there. Scientists differ as to precisely where in the sea life arose: the Miller-Urey experiments suggested a dilute chemical "soup" in open water, but more recent suggestions include volcanic hot springs, fine-grained clay sediments, or deep-sea "black smoker" vents, all of which would have provided protection from damaging ultraviolet radiation which was not blocked by the early Earth's atmosphere.[4](pp138–140)
+
+Marine habitats can be divided horizontally into coastal and open ocean habitats. Coastal habitats extend from the shoreline to the edge of the continental shelf. Most marine life is found in coastal habitats, even though the shelf area occupies only 7 percent of the total ocean area. Open ocean habitats are found in the deep ocean beyond the edge of the continental shelf. Alternatively, marine habitats can be divided vertically into pelagic (open water), demersal (just above the seabed) and benthic (sea bottom) habitats. A third division is by latitude: from polar seas with ice shelves, sea ice and icebergs, to temperate and tropical waters.[4](pp150–151)
+
+Coral reefs, the so-called "rainforests of the sea", occupy less than 0.1 percent of the world's ocean surface, yet their ecosystems include 25 percent of all marine species.[97] The best-known are tropical coral reefs such as Australia's Great Barrier Reef, but cold water reefs harbour a wide array of species including corals (only six of which contribute to reef formation).[4](pp204–207)[98]
+
+Marine primary producers — plants and microscopic organisms in the plankton — are widespread and very essential for the ecosystem. It has been estimated that half of the world's oxygen is produced by phytoplankton.[99][100] About 45 percent of the sea's primary production of living material is contributed by diatoms.[101] Much larger algae, commonly known as seaweeds, are important locally; Sargassum forms floating drifts, while kelp form seabed forests.[96](pp246–255) Flowering plants in the form of seagrasses grow in "meadows" in sandy shallows,[102] mangroves line the coast in tropical and subtropical regions[103] and salt-tolerant plants thrive in regularly inundated salt marshes.[104] All of these habitats are able to sequester large quantities of carbon and support a biodiverse range of larger and smaller animal life.[105]
+
+Light is only able to penetrate the top 200 metres (660 ft) so this is the only part of the sea where plants can grow.[36] The surface layers are often deficient in biologically active nitrogen compounds. The marine nitrogen cycle consists of complex microbial transformations which include the fixation of nitrogen, its assimilation, nitrification, anammox and denitrification.[106] Some of these processes take place in deep water so that where there is an upwelling of cold waters, and also near estuaries where land-sourced nutrients are present, plant growth is higher. This means that the most productive areas, rich in plankton and therefore also in fish, are mainly coastal.[4](pp160–163)
+
+There is a broader spectrum of higher animal taxa in the sea than on land, many marine species have yet to be discovered and the number known to science is expanding annually.[107] Some vertebrates such as seabirds, seals and sea turtles return to the land to breed but fish, cetaceans and sea snakes have a completely aquatic lifestyle and many invertebrate phyla are entirely marine. In fact, the oceans teem with life and provide many varying microhabitats.[107] One of these is the surface film which, even though tossed about by the movement of waves, provides a rich environment and is home to bacteria, fungi, microalgae, protozoa, fish eggs and various larvae.[108]
+
+The pelagic zone contains macro- and microfauna and myriad zooplankton which drift with the currents. Most of the smallest organisms are the larvae of fish and marine invertebrates which liberate eggs in vast numbers because the chance of any one embryo surviving to maturity is so minute.[109] The zooplankton feed on phytoplankton and on each other and form a basic part of the complex food chain that extends through variously sized fish and other nektonic organisms to large squid, sharks, porpoises, dolphins and whales.[110] Some marine creatures make large migrations, either to other regions of the ocean on a seasonal basis or vertical migrations daily, often ascending to feed at night and descending to safety by day.[111] Ships can introduce or spread invasive species through the discharge of ballast water or the transport of organisms that have accumulated as part of the fouling community on the hulls of vessels.[112]
+
+The demersal zone supports many animals that feed on benthic organisms or seek protection from predators and the seabed provides a range of habitats on or under the surface of the substrate which are used by creatures adapted to these conditions. The tidal zone with its periodic exposure to the dehydrating air is home to barnacles, molluscs and crustaceans. The neritic zone has many organisms that need light to flourish. Here, among algal encrusted rocks live sponges, echinoderms, polychaete worms, sea anemones and other invertebrates. Corals often contain photosynthetic symbionts and live in shallow waters where light penetrates. The extensive calcareous skeletons they extrude build up into coral reefs which are an important feature of the seabed. These provide a biodiverse habitat for reef dwelling organisms. There is less sea life on the floor of deeper seas but marine life also flourishes around seamounts that rise from the depths, where fish and other animals congregate to spawn and feed. Close to the seabed live demersal fish that feed largely on pelagic organisms or benthic invertebrates.[113] Exploration of the deep sea by submersibles revealed a new world of creatures living on the seabed that scientists had not previously known to exist. Some like the detrivores rely on organic material falling to the ocean floor. Others cluster round deep sea hydrothermal vents where mineral-rich flows of water emerge from the seabed, supporting communities whose primary producers are sulphide-oxidising chemoautotrophic bacteria, and whose consumers include specialised bivalves, sea anemones, barnacles, crabs, worms and fish, often found nowhere else.[4](p212) A dead whale sinking to the bottom of the ocean provides food for an assembly of organisms which similarly rely largely on the actions of sulphur-reducing bacteria. Such places support unique biomes where many new microbes and other lifeforms have been discovered.[114]
+
+Humans have travelled the seas since they first built sea-going craft. Mesopotamians were using bitumen to caulk their reed boats and, a little later, masted sails.[115] By c. 3000 BC, Austronesians on Taiwan had begun spreading into maritime Southeast Asia.[116] Subsequently, the Austronesian "Lapita" peoples displayed great feats of navigation, reaching out from the Bismarck Archipelago to as far away as Fiji, Tonga, and Samoa.[117] Their descendants continued to travel thousands of miles between tiny islands on outrigger canoes,[118] and in the process they found many new islands, including Hawaii, Easter Island (Rapa Nui), and New Zealand.[119]
+
+The Ancient Egyptians and Phoenicians explored the Mediterranean and Red Sea with the Egyptian Hannu reaching the Arabian Peninsula and the African Coast around 2750 BC.[120] In the 1st millennium BC, Phoenicians and Greeks established colonies throughout the Mediterranean and the Black Sea.[121] Around 500 BC, the Carthaginian navigator Hanno left a detailed periplus of an Atlantic journey that reached at least Senegal and possibly Mount Cameroon.[122][123] In the early Mediaeval period, the Vikings crossed the North Atlantic and even reached the northeastern fringes of North America.[124] Novgorodians had also been sailing the White Sea since the 13th century or before.[125] Meanwhile, the seas along the eastern and southern Asian coast were used by Arab and Chinese traders.[126] The Chinese Ming Dynasty had a fleet of 317 ships with 37,000 men under Zheng He in the early fifteenth century, sailing the Indian and Pacific Oceans.[4](pp12–13) In the late fifteenth century, Western European mariners started making longer voyages of exploration in search of trade. Bartolomeu Dias rounded the Cape of Good Hope in 1487 and Vasco da Gama reached India via the Cape in 1498. Christopher Columbus sailed from Cadiz in 1492, attempting to reach the eastern lands of India and Japan by the novel means of travelling westwards. He made landfall instead on an island in the Caribbean Sea and a few years later, the Venetian navigator John Cabot reached Newfoundland. The Italian Amerigo Vespucci, after whom America was named, explored the South American coastline in voyages made between 1497 and 1502, discovering the mouth of the Amazon River.[4](pp12–13) In 1519 the Portuguese navigator Ferdinand Magellan led the Spanish Magellan-Elcano expedition which would be the first to sail around the world.[4](pp12–13)
+
+As for the history of navigational instrument, a compass was first used by the ancient Greeks and Chinese to show where north lies and the direction in which the ship is heading. The latitude (an angle which ranges from 0° at the equator to 90° at the poles) was determined by measuring the angle between the Sun, Moon or a specific star and the horizon by the use of an astrolabe, Jacob's staff or sextant. The longitude (a line on the globe joining the two poles) could only be calculated with an accurate chronometer to show the exact time difference between the ship and a fixed point such as the Greenwich Meridian. In 1759, John Harrison, a clockmaker, designed such an instrument and James Cook used it in his voyages of exploration.[127] Nowadays, the Global Positioning System (GPS) using over thirty satellites enables accurate navigation worldwide.[127]
+
+With regards to maps that are vital for navigation, in the second century, Ptolemy mapped the whole known world from the "Fortunatae Insulae", Cape Verde or Canary Islands, eastward to the Gulf of Thailand. This map was used in 1492 when Christopher Columbus set out on his voyages of discovery.[128] Subsequently, Gerardus Mercator made a practical map of the world in 1538, his map projection conveniently making rhumb lines straight.[4](pp12–13) By the eighteenth century better maps had been made and part of the objective of James Cook on his voyages was to further map the ocean. Scientific study has continued with the depth recordings of the Tuscarora, the oceanic research of the Challenger voyages (1872–1876), the work of the Scandinavian seamen Roald Amundsen and Fridtjof Nansen, the Michael Sars expedition in 1910, the German Meteor expedition of 1925, the Antarctic survey work of Discovery II in 1932, and others since.[19] Furthermore, in 1921, the International Hydrographic Organization was set up, and it constitutes the authority on hydrographic surveying and nautical charting.[129]
+
+Scientific oceanography began with the voyages of Captain James Cook from 1768 to 1779, describing the Pacific with unprecedented precision from 71 degrees South to 71 degrees North.[4](p14) John Harrison's chronometers supported Cook's accurate navigation and charting on two of these voyages, permanently improving the standard attainable for subsequent work.[4](p14) Other expeditions followed in the nineteenth century, from Russia, France, the Netherlands and the United States as well as Britain.[4](p15) On HMS Beagle, which provided Charles Darwin with ideas and materials for his 1859 book On the Origin of Species, the ship's captain, Robert FitzRoy, charted the seas and coasts and published his four-volume report of the ship's three voyages in 1839.[4](p15) Edward Forbes's 1854 book, Distribution of Marine Life argued that no life could exist below around 600 metres (2000 feet). This was proven wrong by the British biologists W. B. Carpenter and C. Wyville Thomson, who in 1868 discovered life in deep water by dredging.[4](p15) Wyville Thompson became chief scientist on the Challenger expedition of 1872–1876, which effectively created the science of oceanography.[4](p15)
+
+On her 68,890-nautical-mile (127,580 km) journey round the globe, HMS Challenger discovered about 4,700 new marine species, and made 492 deep sea soundings, 133 bottom dredges, 151 open water trawls and 263 serial water temperature observations.[130] In the southern Atlantic in 1898/1899, Carl Chun on the Valdivia brought many new life forms to the surface from depths of over 4,000 metres (13,000 ft). The first observations of deep-sea animals in their natural environment were made in 1930 by William Beebe and Otis Barton who descended to 434 metres (1,424 ft) in the spherical steel Bathysphere.[131] This was lowered by cable but by 1960 a self-powered submersible, Trieste developed by Jacques Piccard, took Piccard and Don Walsh to the deepest part of the Earth's oceans, the Mariana Trench in the Pacific, reaching a record depth of about 10,915 metres (35,810 ft),[132] a feat not repeated until 2012 when James Cameron piloted the Deepsea Challenger to similar depths.[133] An atmospheric diving suit can be worn for deep sea operations, with a new world record being set in 2006 when a US Navy diver descended to 2,000 feet (610 m) in one of these articulated, pressurized suits.[134]
+
+At great depths, no light penetrates through the water layers from above and the pressure is extreme. For deep sea exploration it is necessary to use specialist vehicles, either remotely operated underwater vehicles with lights and cameras or manned submersibles. The battery-operated Mir submersibles have a three-man crew and can descend to 20,000 feet (6,000 m). They have viewing ports, 5,000-watt lights, video equipment and manipulator arms for collecting samples, placing probes or pushing the vehicle across the sea bed when the thrusters would stir up excessive sediment.[135]
+
+Bathymetry is the mapping and study of the topography of the ocean floor. Methods used for measuring the depth of the sea include single or multibeam echosounders, laser airborne depth sounders and the calculation of depths from satellite remote sensing data. This information is used for determining the routes of undersea cables and pipelines, for choosing suitable locations for siting oil rigs and offshore wind turbines and for identifying possible new fisheries.[136]
+
+Ongoing oceanographic research includes marine lifeforms, conservation, the marine environment, the chemistry of the ocean, the studying and modelling of climate dynamics, the air-sea boundary, weather patterns, ocean resources, renewable energy, waves and currents, and the design and development of new tools and technologies for investigating the deep.[137] Whereas in the 1960s and 1970s research could focus on taxonomy and basic biology, in the 2010s attention has shifted to larger topics such as climate change.[138] Researchers make use of satellite-based remote sensing for surface waters, with research ships, moored observatories and autonomous underwater vehicles to study and monitor all parts of the sea.[139]
+
+"Freedom of the seas" is a principle in international law dating from the seventeenth century. It stresses freedom to navigate the oceans and disapproves of war fought in international waters.[140] Today, this concept is enshrined in the United Nations Convention on the Law of the Sea (UNCLOS), the third version of which came into force in 1994. Article 87(1) states: "The high seas are open to all states, whether coastal or land-locked." Article 87(1) (a) to (f) gives a non-exhaustive list of freedoms including navigation, overflight, the laying of submarine cables, building artificial islands, fishing and scientific research.[140] The safety of shipping is regulated by the International Maritime Organization. Its objectives include developing and maintaining a regulatory framework for shipping, maritime safety, environmental concerns, legal matters, technical co-operation and maritime security.[141]
+
+UNCLOS defines various areas of water. "Internal waters" are on the landward side of a baseline and foreign vessels have no right of passage in these. "Territorial waters" extend to 12 nautical miles (22 kilometres; 14 miles) from the coastline and in these waters, the coastal state is free to set laws, regulate use and exploit any resource. A "contiguous zone" extending a further 12 nautical miles allows for hot pursuit of vessels suspected of infringing laws in four specific areas: customs, taxation, immigration and pollution. An "exclusive economic zone" extends for 200 nautical miles (370 kilometres; 230 miles) from the baseline. Within this area, the coastal nation has sole exploitation rights over all natural resources. The "continental shelf" is the natural prolongation of the land territory to the continental margin's outer edge, or 200 nautical miles from the coastal state's baseline, whichever is greater. Here the coastal nation has the exclusive right to harvest minerals and also living resources "attached" to the seabed.[140]
+
+Control of the sea is important to the security of a maritime nation, and the naval blockade of a port can be used to cut off food and supplies in time of war. Battles have been fought on the sea for more than 3,000 years. In about 1210 B.C., Suppiluliuma II, the king of the Hittites, defeated and burned a fleet from Alashiya (modern Cyprus).[142] In the decisive 480 B.C. Battle of Salamis, the Greek general Themistocles trapped the far larger fleet of the Persian king Xerxes in a narrow channel and attacked vigorously, destroying 200 Persian ships for the loss of 40 Greek vessels.[143] At the end of the Age of Sail, the English navy, led by Horatio Nelson, broke the power of the combined French and Spanish fleets at the 1805 Battle of Trafalgar.[144]
+
+With steam and the industrial production of steel plate came greatly increased firepower in the shape of the dreadnought battleships armed with long-range guns. In 1905, the Japanese fleet decisively defeated the Russian fleet, which had travelled over 18,000 nautical miles (33,000 km), at the Battle of Tsushima.[145] Dreadnoughts fought inconclusively in the First World War at the 1916 Battle of Jutland between the Royal Navy's Grand Fleet and the Imperial German Navy's High Seas Fleet.[146] In the Second World War, the British victory at the 1940 Battle of Taranto showed that naval air power was sufficient to overcome the largest warships,[147] foreshadowing the decisive sea-battles of the Pacific War including the Battles of the Coral Sea, Midway, the Philippine Sea, and the climactic Battle of Leyte Gulf, in all of which the dominant ships were aircraft carriers.[148][149]
+
+Submarines became important in naval warfare in World War I, when German submarines, known as U-boats, sank nearly 5,000 Allied merchant ships,[150] including however the RMS Lusitania, so helping to bring the United States into the war.[151] In World War II, almost 3,000 Allied ships were sunk by U-boats attempting to block the flow of supplies to Britain,[152] but the Allies broke the blockade in the Battle of the Atlantic, which lasted the whole length of the war, sinking 783 U-boats.[153] Since 1960, several nations have maintained fleets of nuclear-powered ballistic missile submarines, vessels equipped to launch ballistic missiles with nuclear warheads from under the sea. Some of these are kept permanently on patrol.[154][155]
+
+Sailing ships or packets carried mail overseas, one of the earliest being the Dutch service to Batavia in the 1670s.[156] These added passenger accommodation, but in cramped conditions. Later, scheduled services were offered but the time journeys took depended much on the weather. When steamships replaced sailing vessels, ocean-going liners took over the task of carrying people. By the beginning of the twentieth century, crossing the Atlantic took about five days and shipping companies competed to own the largest and fastest vessels. The Blue Riband was an unofficial accolade given to the fastest liner crossing the Atlantic in regular service. The Mauretania held the title with 26.06 knots (48.26 km/h) for twenty years from 1909.[157] The Hales Trophy, another award for the fastest commercial crossing of the Atlantic, was won by the United States in 1952 for a crossing that took three days, ten hours and forty minutes.[158]
+
+The great liners were comfortable but expensive in fuel and staff. The age of the trans-Atlantic liners waned as cheap intercontinental flights became available. In 1958, a regular scheduled air service between New York and Paris taking seven hours doomed the Atlantic ferry service to oblivion. One by one the vessels were laid up, some were scrapped, others became cruise ships for the leisure industry and still others floating hotels.[159]
+
+Maritime trade has existed for millennia. The Ptolemaic dynasty had developed trade with India using the Red Sea ports and in the first millennium BC the Arabs, Phoenicians, Israelites and Indians traded in luxury goods such as spices, gold, and precious stones.[160] The Phoenicians were noted sea traders and under the Greeks and Romans, commerce continued to thrive. With the collapse of the Roman Empire, European trade dwindled but it continued to flourish among the kingdoms of Africa, the Middle East, India, China and southeastern Asia.[161] From the 16th to the 19th centuries, about 13 million people were shipped across the Atlantic to be sold as slaves in the Americas.[162]
+
+Nowadays, large quantities of goods are transported by sea, especially across the Atlantic and around the Pacific Rim. A major trade route passes through the Pillars of Hercules, across the Mediterranean and the Suez Canal to the Indian Ocean and through the Straits of Malacca; much trade also passes through the English Channel.[163] Shipping lanes are the routes on the open sea used by cargo vessels, traditionally making use of trade winds and currents. Over 60 percent of the world's container traffic is conveyed on the top twenty trade routes.[164] Increased melting of Arctic ice since 2007 enables ships to travel the Northwest Passage for some weeks in summertime, avoiding the longer routes via the Suez Canal or the Panama Canal.[165]
+Shipping is supplemented by air freight, a more expensive process mostly used for particularly valuable or perishable cargoes. Seaborne trade carries more than US$4 trillion worth of goods each year.[166]
+
+There are two main kinds of freight, bulk cargo and break bulk or general cargo, most of which is now transported in containers. Commodities in the form of liquids, powder or particles are carried loose in the holds of bulk carriers and include oil, grain, coal, ore, scrap metal, sand and gravel. Break bulk cargo is usually manufactured goods and is transported in packages, often stacked on pallets. Before the arrival of containerization in the 1950s, these goods were loaded, transported and unloaded piecemeal.[167] The use of containers has greatly increased the efficiency and decreased the cost of moving them[168] with most freight now traveling in standard sized, lockable containers loaded on purpose-built container ships at dedicated terminals.[169][169] Freight forwarding firms book cargo, arrange pickup and delivery, and manage documentation.[170]
+
+Fish and other fishery products are among the most widely consumed sources of protein and other essential nutrients.[171] In 2009, 16.6% of the world's intake of animal protein and 6.5% of all protein consumed came from fish.[171] In order to fulfill this need, coastal countries have exploited marine resources in their exclusive economic zone, although fishing vessels are increasingly venturing further afield to exploit stocks in international waters.[172] In 2011, the total world production of fish, including aquaculture, was estimated to be 154 million tonnes, of which most was for human consumption.[171] The harvesting of wild fish accounted for 90.4 million tonnes, while annually increasing aquaculture contributes the rest.[171] The north west Pacific is by far the most productive area with 20.9 million tonnes (27 percent of the global marine catch) in 2010.[171] In addition, the number of fishing vessels in 2010 reached 4.36 million, whereas the number of people employed in the primary sector of fish production in the same year amounted to 54.8 million.[171]
+
+Modern fishing vessels include fishing trawlers with a small crew, stern trawlers, purse seiners, long-line factory vessels and large factory ships which are designed to stay at sea for weeks, processing and freezing great quantities of fish. The equipment used to capture the fish may be purse seines, other seines, trawls, dredges, gillnets and long-lines and the fish species most frequently targeted are herring, cod, anchovy, tuna, flounder, mullet, squid and salmon. Overexploitation itself has become a serious concern; it does not only cause the depletion of fish stocks, but also substantially reduce the size of predatory fish populations.[173] It has been estimated that "industrialized fisheries typically reduced community biomass by 80% within 15 years of exploitation."[173] In order to avoid overexploitation, many countries have introduced quotas in their own waters.[174] However, recovery efforts often entail substantial costs to local economies or food provision. Nonetheless, research published in Nature in April 2018 found that the aggressive effort of the Indonesian Minister of Maritime Affairs and Fisheries of Indonesia Susi Pudjiastuti to curtail illegal fishing has "reduced total fishing effort by at least 25%, (...) [potentially] generate a 14% increase in catch and a 12% increase in profit."[175] Therefore, the paper concluded that "many nations can recover their fisheries while avoiding these short-term costs by sharply addressing illegal, unreported and unregulated (IUU) fishing."[175]
+
+Artisan fishing methods include rod and line, harpoons, skin diving, traps, throw nets and drag nets. Traditional fishing boats are powered by paddle, wind or outboard motors and operate in near-shore waters. The Food and Agriculture Organization is encouraging the development of local fisheries to provide food security to coastal communities and help alleviate poverty.[176]
+
+As well as the wild stock, about 79 million tonnes (78M long tons; 87M short tons) of food and non-food products were produced by aquaculture in 2010, an all-time high. About six hundred species of plants and animals were cultured, some for use in seeding wild populations. The animals raised included finfish, aquatic reptiles, crustaceans, molluscs, sea cucumbers, sea urchins, sea squirts and jellyfish.[171] Integrated mariculture has the advantage that there is a readily available supply of planktonic food in the ocean, and waste is removed naturally.[177] Various methods are employed. Mesh enclosures for finfish can be suspended in the open seas, cages can be used in more sheltered waters or ponds can be refreshed with water at each high tide. Shrimps can be reared in shallow ponds connected to the open sea.[178] Ropes can be hung in water to grow algae, oysters and mussels. Oysters can be reared on trays or in mesh tubes. Sea cucumbers can be ranched on the seabed.[179] Captive breeding programmes have raised lobster larvae for release of juveniles into the wild resulting in an increased lobster harvest in Maine.[180] At least 145 species of seaweed – red, green, and brown algae – are eaten worldwide, and some have long been farmed in Japan and other Asian countries; there is great potential for additional algaculture.[181] Few maritime flowering plants are widely used for food but one example is marsh samphire which is eaten both raw and cooked.[182] A major difficulty for aquaculture is the tendency towards monoculture and the associated risk of widespread disease. In the 1990s, disease wiped out China's farmed Farrer's scallop and white shrimp and required their replacement by other species.[183] Aquaculture is also associated with environmental risks; for instance, shrimp farming has caused the destruction of important mangrove forests throughout southeast Asia.[184]
+
+Use of the sea for leisure developed in the nineteenth century, and became a significant industry in the twentieth century.[185] Maritime leisure activities are varied, and include self-organized trips cruising, yachting, powerboat racing[186] and fishing;[187] commercially organized voyages on cruise ships;[188] and trips on smaller vessels for ecotourism such as whale watching and coastal birdwatching.[189]
+
+Humans enjoy venturing into the sea; children paddle and splash in the shallows and many people take pleasure in bathing and relaxing on the beach. This was not always the case, with sea bathing becoming the vogue in Europe in the 18th century after Dr. William Buchan advocated the practice for health reasons.[190] Surfing is a sport in which a wave is ridden by a surfer, with or without a surfboard. Other marine water sports include kite surfing, where a power kite propels a manned board across the water,[191] windsurfing, where the power is provided by a fixed, manoeuvrable sail[192] and water skiing, where a powerboat is used to pull a skier.[193]
+
+Beneath the surface, freediving is necessarily restricted to shallow descents. Pearl divers have traditionally greased their skins, put cotton in their ears and clips on their noses and dived to 40 feet (12 m) with baskets to collect oysters.[194] Human eyes are not adapted for use underwater but vision can be improved by wearing a diving mask. Other useful equipment includes fins and snorkels, and scuba equipment allows underwater breathing and hence a longer time can be spent beneath the surface.[195] The depths that can be reached by divers and the length of time they can stay underwater is limited by the increase of pressure they experience as they descend and the need to prevent decompression sickness as they return to the surface. Recreational divers are advised to restrict themselves to depths of 100 feet (30 m) beyond which the danger of nitrogen narcosis increases. Deeper dives can be made with specialised equipment and training.[195]
+
+The sea offers a very large supply of energy carried by ocean waves, tides, salinity differences, and ocean temperature differences which can be harnessed to generate electricity.[196] Forms of 'green' marine energy include tidal power, marine current power, osmotic power, ocean thermal energy and wave power.[196][197]
+
+Tidal power uses generators to produce electricity from tidal flows, sometimes by using a dam to store and then release seawater. The Rance barrage, 1 kilometre (0.62 mi) long, near St Malo in Brittany opened in 1967; it generates about 0.5 GW, but it has been followed by few similar schemes.[4](pp111–112)
+
+The large and highly variable energy of waves gives them enormous destructive capability, making affordable and reliable wave machines problematic to develop. A small 2 MW commercial wave power plant, "Osprey", was built in Northern Scotland in 1995 about 300 metres (1000 ft) offshore. It was soon damaged by waves, then destroyed by a storm.[4](p112) Marine current power could provide populated areas close to the sea with a significant part of their energy needs.[198] In principle, it could be harnessed by open-flow turbines; sea bed systems are available, but limited to a depth of about 40 metres (130 ft).[199]
+
+Offshore wind power is captured by wind turbines placed out at sea; it has the advantage that wind speeds are higher than on land, though wind farms are more costly to construct offshore.[200] The first offshore wind farm was installed in Denmark in 1991,[201] and the installed capacity of European offshore wind farms reached 3 GW in 2010.[202]
+
+Electricity power stations are often located on the coast or beside an estuary so that the sea can be used as a heat sink. A colder heat sink enables more efficient power generation, which is important for expensive nuclear power plants in particular.[203]
+
+The seabed contains enormous reserves of minerals which can be exploited by dredging. This has advantages over land-based mining in that equipment can be built at specialised shipyards and infrastructure costs are lower. Disadvantages include problems caused by waves and tides, the tendency for excavations to silt up and the washing away of spoil heaps. There is a risk of coastal erosion and environmental damage.[204]
+
+Seafloor massive sulphide deposits are potential sources of silver, gold, copper, lead and zinc and trace metals since their discovery in the 1960s. They form when geothermally heated water is emitted from deep sea hydrothermal vents known as "black smokers". The ores are of high quality but prohibitively costly to extract.[205] Small scale mining of the deep sea floor is being developed off the coast of Papua New Guinea using robotic techniques, but the obstacles are formidable.[206]
+
+There are large deposits of petroleum, as oil and natural gas, in rocks beneath the seabed. Offshore platforms and drilling rigs extract the oil or gas and store it for transport to land. Offshore oil and gas production can be difficult due to the remote, harsh environment.[207] Drilling for oil in the sea has environmental impacts. Animals may be disorientated by seismic waves used to locate deposits, and there is debate as to whether this causes the beaching of whales.[208] Toxic substances such as mercury, lead and arsenic may be released. The infrastructure may cause damage, and oil may be spilt.[209]
+
+Large quantities of methane clathrate exist on the seabed and in ocean sediment at a temperature of around 2 °C (36 °F) and these are of interest as a potential energy source. Some estimates put the amount available at between one and 5 million cubic kilometres (0.24 to 1.2 million cubic miles).[210] Also on the seabed are manganese nodules formed of layers of iron, manganese and other hydroxides around a core. In the Pacific these may cover up to 30 percent of the deep ocean floor. The minerals precipitate from seawater and grow very slowly. Their commercial extraction for nickel was investigated in the 1970s but abandoned in favour of more convenient sources.[211] In suitable locations, diamonds are gathered from the seafloor using suction hoses to bring gravel ashore. In deeper waters, mobile seafloor crawlers are used and the deposits are pumped to a vessel above. In Namibia, more diamonds are now collected from marine sources than by conventional methods on land.[212]
+
+The sea holds enormous quantities of valuable dissolved minerals.[213] The most important, Salt for table and industrial use has been harvested by solar evaporation from shallow ponds since prehistoric times. Bromine, accumulated after being leached from the land, is economically recovered from the Dead Sea, where it occurs at 55,000 parts per million (ppm).[214]
+
+Desalination is the technique of removing salts from seawater to leave fresh water suitable for drinking or irrigation. The two main processing methods, vacuum distillation and reverse osmosis, use large quantities of energy. Desalination is normally only undertaken where fresh water from other sources is in short supply or energy is plentiful, as in the excess heat generated by power stations. The brine produced as a by-product contains some toxic materials and is returned to the sea.[215]
+
+Many substances enter the sea as a result of human activities. Combustion products are transported in the air and deposited into the sea by precipitation. Industrial outflows and sewage contribute heavy metals, pesticides, PCBs, disinfectants, household cleaning products and other synthetic chemicals. These become concentrated in the surface film and in marine sediment, especially estuarine mud. The result of all this contamination is largely unknown because of the large number of substances involved and the lack of information on their biological effects.[216] The heavy metals of greatest concern are copper, lead, mercury, cadmium and zinc which may be bio-accumulated by marine organisms and are passed up the food chain.[217]
+
+Much floating plastic rubbish does not biodegrade, instead disintegrating over time and eventually breaking down to the molecular level. Rigid plastics may float for years.[218] In the centre of the Pacific gyre there is a permanent floating accumulation of mostly plastic waste[219] and there is a similar garbage patch in the Atlantic.[220] Foraging sea birds such as the albatross and petrel may mistake debris for food, and accumulate indigestible plastic in their digestive systems. Turtles and whales have been found with plastic bags and fishing line in their stomachs. Microplastics may sink, threatening filter feeders on the seabed.[221]
+
+Most oil pollution in the sea comes from cities and industry.[222] Oil is dangerous for marine animals. It can clog the feathers of sea birds, reducing their insulating effect and the birds' buoyancy, and be ingested when they preen themselves in an attempt to remove the contaminant. Marine mammals are less seriously affected but may be chilled through the removal of their insulation, blinded, dehydrated or poisoned. Benthic invertebrates are swamped when the oil sinks, fish are poisoned and the food chain is disrupted. In the short term, oil spills result in wildlife populations being decreased and unbalanced, leisure activities being affected and the livelihoods of people dependant on the sea being devastated.[223] The marine environment has self-cleansing properties and naturally occurring bacteria will act over time to remove oil from the sea. In the Gulf of Mexico, where oil-eating bacteria are already present, they take only a few days to consume spilt oil.[224]
+
+Run-off of fertilisers from agricultural land is a major source of pollution in some areas and the discharge of raw sewage has a similar effect. The extra nutrients provided by these sources can cause excessive plant growth. Nitrogen is often the limiting factor in marine systems, and with added nitrogen, algal blooms and red tides can lower the oxygen level of the water and kill marine animals. Such events have created dead zones in the Baltic Sea and the Gulf of Mexico.[222] Some algal blooms are caused by cyanobacteria that make shellfish that filter feed on them toxic, harming animals like sea otters.[225] Nuclear facilities too can pollute. The Irish Sea was contaminated by radioactive caesium-137 from the former Sellafield nuclear fuel processing plant[226] and nuclear accidents may also cause radioactive material to seep into the sea, as did the disaster at the Fukushima Daiichi Nuclear Power Plant in 2011.[227]
+
+The dumping of waste (including oil, noxious liquids, sewage and garbage) at sea is governed by international law. The London Convention (1972) is a United Nations agreement to control ocean dumping which had been ratified by 89 countries by 8 June 2012.[228] MARPOL 73/78 is a convention to minimize pollution of the seas by ships. By May 2013, 152 maritime nations had ratified MARPOL.[229]
+
+Several nomadic indigenous groups in Maritime Southeast Asia live in boats and derive nearly all they need from the sea. The Moken people live on the coasts of Thailand and Burma and islands in the Andaman Sea.[230] The Bajau people are originally from the Sulu Archipelago, Mindanao and northern Borneo.[231] Some Sea Gypsies are accomplished free-divers, able to descend to depths of 30 metres (98 ft), though many are adopting a more settled, land-based way of life.[232][233]
+
+The indigenous peoples of the Arctic such as the Chukchi, Inuit, Inuvialuit and Yup'iit hunt marine mammals including seals and whales,[234] and the Torres Strait Islanders of Australia include ownership of the Great Barrier Reef among their possessions. They live a traditional life on the islands involving hunting, fishing, gardening and trading with neighbouring peoples in Papua and mainland Aboriginal Australians.[235]
+
+The sea appears in human culture in contradictory ways, as both powerful but serene and as beautiful but dangerous.[4](p10) It has its place in literature, art, poetry, film, theatre, classical music, mythology and dream interpretation.[236] The Ancients personified it, believing it to be under the control of a being who needed to be appeased, and symbolically, it has been perceived as a hostile environment populated by fantastic creatures; the Leviathan of the Bible,[237] Scylla in Greek mythology,[238] Isonade in Japanese mythology,[239] and the kraken of late Norse mythology.[240]
+
+The sea and ships have been depicted in art ranging from simple drawings on the walls of huts in Lamu[236] to seascapes by Joseph Turner. In Dutch Golden Age painting, artists such as Jan Porcellis, Hendrick Dubbels, Willem van de Velde the Elder and his son, and Ludolf Bakhuizen celebrated the sea and the Dutch navy at the peak of its military prowess.[241][242] The Japanese artist Katsushika Hokusai created colour prints of the moods of the sea, including The Great Wave off Kanagawa.[4](p8)
+
+Music too has been inspired by the ocean, sometimes by composers who lived or worked near the shore and saw its many different aspects. Sea shanties, songs that were chanted by mariners to help them perform arduous tasks, have been woven into compositions and impressions in music have been created of calm waters, crashing waves and storms at sea.[243] Classical sea-related music includes Richard Wagner's The Flying Dutchman,[244] Claude Debussy's La mer (1903–05),[245] Charles Villiers Stanford's Songs of the Sea (1904) and Songs of the Fleet (1910), Edward Elgar's Sea Pictures (1899) and Ralph Vaughan Williams' A Sea Symphony (1903–1909).[246]
+
+As a symbol, the sea has for centuries played a role in literature, poetry and dreams. Sometimes it is there just as a gentle background but often it introduces such themes as storm, shipwreck, battle, hardship, disaster, the dashing of hopes and death.[247] In his epic poem the Odyssey, written in the 8th century BC,[248] Homer describes the ten-year voyage of the Greek hero Odysseus who struggles to return home across the sea's many hazards after the war described in the Iliad.[249] The sea is a recurring theme in the Haiku poems of the Japanese Edo period poet Matsuo Bashō (松尾 芭蕉) (1644–1694).[250] In modern literature, sea-inspired novels have been written by Joseph Conrad — drawn from his experience at sea,[251] Herman Wouk,[252] and Herman Melville.[253] In the works of psychiatrist Carl Jung, the sea symbolizes the personal and the collective unconscious in dream interpretation, the depths of the sea symbolizing the depths of the unconscious mind.[254]
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+A prime meridian is the meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its anti-meridian (the 180th meridian in a 360°-system) form a great circle. This great circle divides a spheroid into two hemispheres. If one uses directions of East and West from a defined prime meridian, then they can be called the Eastern Hemisphere and the Western Hemisphere.
+
+A prime meridian is ultimately arbitrary, unlike an equator, which is determined by the axis of rotation.  For Earth's prime meridian, various conventions have been used or advocated in different regions throughout history.[1] The most widely used modern meridian is the IERS Reference Meridian. It is derived but deviates slightly from the Greenwich Meridian, which was selected as an international standard in 1884.
+
+Longitudes for the Earth and Moon are measured from their prime meridian at 0° to 180° east and to 180° west. For all other Solar System bodies, longitude is measured from 0° (their prime meridian) to 360°. West longitudes are used if the rotation of the body is direct, that is, it follows the right hand rule. East longitudes are used if the rotation is retrograde.[2]
+
+The notion of longitude was developed by the Greek Eratosthenes (c. 276 BC – c. 195 BC) in Alexandria, and Hipparchus (c. 190 BC – c. 120 BC) in Rhodes, and applied to a large number of cities by the geographer Strabo (64/63 BC – c. 24 AD). But it was Ptolemy (c. AD 90 – c. AD 168) who first used a consistent meridian for a world map in his Geographia.
+
+Ptolemy used as his basis the "Fortunate Isles", a group of islands in the Atlantic, which are usually associated with the Canary Islands (13° to 18°W), although his maps correspond more closely to the Cape Verde islands (22° to 25° W). The main point is to be comfortably west of the western tip of Africa (17.5° W) as negative numbers were not yet in use. His prime meridian corresponds to 18° 40' west of Winchester (about 20°W) today.[3] At that time the chief method of determining longitude was by using the reported times of lunar eclipses in different countries.
+
+Ptolemy's Geographia was first printed with maps at Bologna in 1477, and many early globes in the 16th century followed his lead. But there was still a hope that a "natural" basis for a prime meridian existed. Christopher Columbus reported (1493) that the compass pointed due north somewhere in mid-Atlantic, and this fact was used in the important Treaty of Tordesillas of 1494, which settled the territorial dispute between Spain and Portugal over newly discovered lands. The Tordesillas line was eventually settled at 370 leagues (2,193 kilometers, 1,362 statute miles, or 1,184 nautical miles).[note 1] west of Cape Verde. This is shown in Diogo Ribeiro's 1529 map. São Miguel Island (25.5°W) in the Azores was still used for the same reason as late as 1594 by Christopher Saxton, although by then it had been shown that the zero magnetic deviation line did not follow a line of longitude.[8]
+
+In 1541, Mercator produced his famous 41 cm terrestrial globe and drew his prime meridian precisely through Fuerteventura (14°1'W) in the Canaries. His later maps used the Azores, following the magnetic hypothesis. But by the time that Ortelius produced the first modern atlas in 1570, other islands such as Cape Verde were coming into use. In his atlas longitudes were counted from 0° to 360°, not 180°W to 180°E as is usual today. This practice was followed by navigators well into the 18th century.[9] In 1634, Cardinal Richelieu used the westernmost island of the Canaries, Ferro, 19° 55' west of Paris, as the choice of meridian. The geographer Delisle decided to round this off to 20°, so that it simply became the meridian of Paris disguised.[10]
+
+In the early 18th century the battle was on to improve the determination of longitude at sea, leading to the development of the marine chronometer by John Harrison. But it was the development of accurate star charts, principally by the first British Astronomer Royal, John Flamsteed between 1680 and 1719 and disseminated by his successor Edmund Halley, that enabled navigators to use the lunar method of determining longitude more accurately using the octant developed by Thomas Godfrey and John Hadley.[11]
+
+In the 18th century most countries in Europe adapted their own prime meridian, usually through their capital, hence in France the Paris meridian was prime, in Germany it was the Berlin meridian, in Denmark the Copenhagen meridian, and in United Kingdom the Greenwich meridian.
+
+Between 1765 and 1811, Nevil Maskelyne published 49 issues of the Nautical Almanac based on the meridian of the Royal Observatory, Greenwich. "Maskelyne's tables not only made the lunar method practicable, they also made the Greenwich meridian the universal reference point. Even the French translations of the Nautical Almanac retained Maskelyne's calculations from Greenwich—in spite of the fact that every other table in the Connaissance des Temps considered the Paris meridian as the prime."[12]
+
+In 1884, at the International Meridian Conference in Washington, D.C., 22 countries voted to adopt the Greenwich[13] meridian as the prime meridian of the world. The French argued for a neutral line, mentioning the Azores and the Bering Strait, but eventually abstained and continued to use the Paris meridian until 1911.
+
+In October 1884 the Greenwich Meridian was selected by delegates (forty-one delegates representing twenty-five nations) to the International Meridian Conference held in Washington, D.C., United States to be the common zero of longitude and standard of time reckoning throughout the world.[38][note 2] The modern prime meridian, the IERS Reference Meridian, is placed very near this meridian and is the prime meridian that currently has the widest use.
+
+The modern prime meridian, based at the Royal Observatory, Greenwich, was established by Sir George Airy in 1851.[40]
+
+The position of the Greenwich Meridian has been defined by the location of the Airy Transit Circle ever since the first observation was taken with it by Sir George Airy in 1851.[40] Prior to that, it was defined by a succession of earlier transit instruments, the first of which was acquired by the second Astronomer Royal, Edmond Halley in 1721. It was set up in the extreme north-west corner of the Observatory between Flamsteed House and the Western Summer House. This spot, now subsumed into Flamsteed House, is roughly 43 metres to the west of the Airy Transit Circle, a distance equivalent to roughly 2 seconds of longitude.[27] It was Airy's transit circle that was adopted in principle (with French delegates, who pressed for adoption of the Paris meridian abstaining) as the Prime Meridian of the world at the 1884 International Meridian Conference.[41][42]
+
+All of these Greenwich meridians were located via an astronomic observation from the surface of the Earth, oriented via a plumb line along the direction of gravity at the surface. This astronomic Greenwich meridian was disseminated around the world, first via the lunar distance method, then by chronometers carried on ships, then via telegraph lines carried by submarine communications cables, then via radio time signals. One remote longitude ultimately based on the Greenwich meridian using these methods was that of the North American Datum 1927 or NAD27, an ellipsoid whose surface best matches mean sea level under the United States.
+
+Beginning in 1973 the International Time Bureau and later the International Earth Rotation and Reference Systems Service changed from reliance on optical instruments like the Airy Transit Circle to techniques such as lunar laser ranging, satellite laser ranging, and very-long-baseline interferometry. The new techniques resulted in the IERS Reference Meridian, the plane of which passes through the centre of mass of the Earth. This differs from the plane established by the Airy transit, which is affected by vertical deflection (the local vertical is affected by influences such as nearby mountains).  The change from relying on the local vertical to using a meridian based on the centre of the Earth caused the modern prime meridian to be 5.3″ east of the astronomic Greenwich prime meridian through the Airy Transit Circle. At the latitude of Greenwich, this amounts to 102 metres.[43] This was officially accepted by the Bureau International de l'Heure (BIH) in 1984 via its BTS84 (BIH Terrestrial System) that later became WGS84 (World Geodetic System 1984) and the various ITRFs (International Terrestrial Reference Systems).
+
+Due to the movement of Earth's tectonic plates, the line of 0° longitude along the surface of the Earth has slowly moved toward the west from this shifted position by a few centimetres; that is, towards the Airy Transit Circle (or the Airy Transit Circle has moved toward the east, depending on your point of view) since 1984 (or the 1960s). With the introduction of satellite technology, it became possible to create a more accurate and detailed global map. With these advances there also arose the necessity to define a reference meridian that, whilst being derived from the Airy Transit Circle, would also take into account the effects of plate movement and variations in the way that the Earth was spinning.[44]
+As a result, the International Reference Meridian was established and is commonly used to denote Earth's prime meridian (0° longitude) by the International Earth Rotation and Reference Systems Service, which defines and maintains the link between longitude and time. Based on observations to satellites and celestial compact radio sources (quasars) from various coordinated stations around the globe, Airy's transit circle drifts northeast about 2.5 centimetres per year relative to this Earth-centred 0° longitude.
+
+It is also the reference meridian of the Global Positioning System operated by the United States Department of Defense, and of WGS84 and its two formal versions, the ideal International Terrestrial Reference System (ITRS) and its realization, the International Terrestrial Reference Frame (ITRF).[45][46][47] A current convention on the Earth uses the opposite of the IRM as the basis for the International Date Line.
+
+On Earth, starting at the North Pole and heading south to the South Pole, the IERS Reference Meridian (as of 2016) passes through:
+
+As on the Earth, prime meridians must be arbitrarily defined. Often a landmark such as a crater is used; other times a prime meridian is defined by reference to another celestial object, or by magnetic fields.
+The prime meridians of the following planetographic systems have been defined:

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+Meridian, or a meridian line may refer to