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Consequently, the smallest atom is helium with a radius of 32 pm, while one of the largest is caesium at 225 pm. When subjected to external forces, like electrical fields, the shape of an atom may deviate from spherical symmetry. The deformation depends on the field magnitude and the orbital type of outer shell electrons, as shown by group-theoretical considerations. Aspherical deviations might be elicited for instance in crystals, where large crystal-electrical fields may occur at low-symmetry lattice sites. Significant ellipsoidal deformations have been shown to occur for sulfur ions and chalcogen ions in pyrite-type compounds. Atomic dimensions are thousands of times smaller than the wavelengths of light (400–700 nm) so they cannot be viewed using an optical microscope, although individual atoms can be observed using a scanning tunneling microscope. To visualize the minuteness of the atom, consider that a typical human hair is about 1 million carbon atoms in width. A single drop of water contains about 2 sextillion () atoms of oxygen, and twice the number of hydrogen atoms. A single carat diamond with a mass of contains about 10 sextillion (1022) atoms of carbon. If an apple were magnified to the size of the Earth, then the atoms in the apple would be approximately the size of the original apple. Radioactive decay Every element has one or more isotopes that have unstable nuclei that are subject to radioactive decay, causing the nucleus to emit particles or electromagnetic radiation. Radioactivity can occur when the radius of a nucleus is large compared with the radius of the strong force, which only acts over distances on the order of 1 fm. The most common forms of radioactive decay are: Alpha decay: this process is caused when the nucleus emits an alpha particle, which is a helium nucleus consisting of two protons and two neutrons. The result of the emission is a new element with a lower atomic number. Beta decay (and electron capture): these processes are regulated by the weak force, and result from a transformation of a neutron into a proton, or a proton into a neutron. The neutron to proton transition is accompanied by the emission of an electron and an antineutrino, while proton to neutron transition (except in electron capture) causes the emission of a positron and a neutrino. The electron or positron emissions are called beta particles. Beta decay either increases or decreases the atomic number of the nucleus by one. Electron capture is more common than positron emission, because it requires less energy. In this type of decay, an electron is absorbed by the nucleus, rather than a positron emitted from the nucleus. A neutrino is still emitted in this process, and a proton changes to a neutron. Gamma decay: this process results from a change in the energy level of the nucleus to a lower state, resulting in the emission of electromagnetic radiation.

Consequently, the smallest atom is helium with a radius of 32 pm, while one of the largest is caesium at 225 pm. When subjected to external forces, like electrical fields, the shape of an atom may deviate from spherical symmetry. The deformation depends on the field magnitude and the orbital type of outer shell electrons, as shown by group-theoretical considerations. Aspherical deviations might be elicited for instance in crystals, where large crystal-electrical fields may occur at low-symmetry lattice sites. Significant ellipsoidal deformations have been shown to occur for sulfur ions and chalcogen ions in pyrite-type compounds. Atomic dimensions are thousands of times smaller than the wavelengths of light (400–700 nm) so they cannot be viewed using an optical microscope, although individual atoms can be observed using a scanning tunneling microscope. To visualize the minuteness of the atom, consider that a typical human hair is about 1 million carbon atoms in width. A single drop of water contains about 2 sextillion () atoms of oxygen, and twice the number of hydrogen atoms. A single carat diamond with a mass of contains about 10 sextillion (1022) atoms of carbon. If an apple were magnified to the size of the Earth, then the atoms in the apple would be approximately the size of the original apple. Radioactive decay Every element has one or more isotopes that have unstable nuclei that are subject to radioactive decay, causing the nucleus to emit particles or electromagnetic radiation. Radioactivity can occur when the radius of a nucleus is large compared with the radius of the strong force, which only acts over distances on the order of 1 fm. The most common forms of radioactive decay are: Alpha decay: this process is caused when the nucleus emits an alpha particle, which is a helium nucleus consisting of two protons and two neutrons. The result of the emission is a new element with a lower atomic number. Beta decay (and electron capture): these processes are regulated by the weak force, and result from a transformation of a neutron into a proton, or a proton into a neutron. The neutron to proton transition is accompanied by the emission of an electron and an antineutrino, while proton to neutron transition (except in electron capture) causes the emission of a positron and a neutrino. The electron or positron emissions are called beta particles. Beta decay either increases or decreases the atomic number of the nucleus by one. Electron capture is more common than positron emission, because it requires less energy. In this type of decay, an electron is absorbed by the nucleus, rather than a positron emitted from the nucleus. A neutrino is still emitted in this process, and a proton changes to a neutron. Gamma decay: this process results from a change in the energy level of the nucleus to a lower state, resulting in the emission of electromagnetic radiation.

The excited state of a nucleus which results in gamma emission usually occurs following the emission of an alpha or a beta particle. Thus, gamma decay usually follows alpha or beta decay. Other more rare types of radioactive decay include ejection of neutrons or protons or clusters of nucleons from a nucleus, or more than one beta particle. An analog of gamma emission which allows excited nuclei to lose energy in a different way, is internal conversion—a process that produces high-speed electrons that are not beta rays, followed by production of high-energy photons that are not gamma rays. A few large nuclei explode into two or more charged fragments of varying masses plus several neutrons, in a decay called spontaneous nuclear fission. Each radioactive isotope has a characteristic decay time period—the half-life—that is determined by the amount of time needed for half of a sample to decay. This is an exponential decay process that steadily decreases the proportion of the remaining isotope by 50% every half-life. Hence after two half-lives have passed only 25% of the isotope is present, and so forth. Magnetic moment Elementary particles possess an intrinsic quantum mechanical property known as spin. This is analogous to the angular momentum of an object that is spinning around its center of mass, although strictly speaking these particles are believed to be point-like and cannot be said to be rotating. Spin is measured in units of the reduced Planck constant (ħ), with electrons, protons and neutrons all having spin ½ ħ, or "spin-½". In an atom, electrons in motion around the nucleus possess orbital angular momentum in addition to their spin, while the nucleus itself possesses angular momentum due to its nuclear spin. The magnetic field produced by an atom—its magnetic moment—is determined by these various forms of angular momentum, just as a rotating charged object classically produces a magnetic field, but the most dominant contribution comes from electron spin. Due to the nature of electrons to obey the Pauli exclusion principle, in which no two electrons may be found in the same quantum state, bound electrons pair up with each other, with one member of each pair in a spin up state and the other in the opposite, spin down state. Thus these spins cancel each other out, reducing the total magnetic dipole moment to zero in some atoms with even number of electrons. In ferromagnetic elements such as iron, cobalt and nickel, an odd number of electrons leads to an unpaired electron and a net overall magnetic moment. The orbitals of neighboring atoms overlap and a lower energy state is achieved when the spins of unpaired electrons are aligned with each other, a spontaneous process known as an exchange interaction. When the magnetic moments of ferromagnetic atoms are lined up, the material can produce a measurable macroscopic field.

The excited state of a nucleus which results in gamma emission usually occurs following the emission of an alpha or a beta particle. Thus, gamma decay usually follows alpha or beta decay. Other more rare types of radioactive decay include ejection of neutrons or protons or clusters of nucleons from a nucleus, or more than one beta particle. An analog of gamma emission which allows excited nuclei to lose energy in a different way, is internal conversion—a process that produces high-speed electrons that are not beta rays, followed by production of high-energy photons that are not gamma rays. A few large nuclei explode into two or more charged fragments of varying masses plus several neutrons, in a decay called spontaneous nuclear fission. Each radioactive isotope has a characteristic decay time period—the half-life—that is determined by the amount of time needed for half of a sample to decay. This is an exponential decay process that steadily decreases the proportion of the remaining isotope by 50% every half-life. Hence after two half-lives have passed only 25% of the isotope is present, and so forth. Magnetic moment Elementary particles possess an intrinsic quantum mechanical property known as spin. This is analogous to the angular momentum of an object that is spinning around its center of mass, although strictly speaking these particles are believed to be point-like and cannot be said to be rotating. Spin is measured in units of the reduced Planck constant (ħ), with electrons, protons and neutrons all having spin ½ ħ, or "spin-½". In an atom, electrons in motion around the nucleus possess orbital angular momentum in addition to their spin, while the nucleus itself possesses angular momentum due to its nuclear spin. The magnetic field produced by an atom—its magnetic moment—is determined by these various forms of angular momentum, just as a rotating charged object classically produces a magnetic field, but the most dominant contribution comes from electron spin. Due to the nature of electrons to obey the Pauli exclusion principle, in which no two electrons may be found in the same quantum state, bound electrons pair up with each other, with one member of each pair in a spin up state and the other in the opposite, spin down state. Thus these spins cancel each other out, reducing the total magnetic dipole moment to zero in some atoms with even number of electrons. In ferromagnetic elements such as iron, cobalt and nickel, an odd number of electrons leads to an unpaired electron and a net overall magnetic moment. The orbitals of neighboring atoms overlap and a lower energy state is achieved when the spins of unpaired electrons are aligned with each other, a spontaneous process known as an exchange interaction. When the magnetic moments of ferromagnetic atoms are lined up, the material can produce a measurable macroscopic field.

The excited state of a nucleus which results in gamma emission usually occurs following the emission of an alpha or a beta particle. Thus, gamma decay usually follows alpha or beta decay. Other more rare types of radioactive decay include ejection of neutrons or protons or clusters of nucleons from a nucleus, or more than one beta particle. An analog of gamma emission which allows excited nuclei to lose energy in a different way, is internal conversion—a process that produces high-speed electrons that are not beta rays, followed by production of high-energy photons that are not gamma rays. A few large nuclei explode into two or more charged fragments of varying masses plus several neutrons, in a decay called spontaneous nuclear fission. Each radioactive isotope has a characteristic decay time period—the half-life—that is determined by the amount of time needed for half of a sample to decay. This is an exponential decay process that steadily decreases the proportion of the remaining isotope by 50% every half-life. Hence after two half-lives have passed only 25% of the isotope is present, and so forth. Magnetic moment Elementary particles possess an intrinsic quantum mechanical property known as spin. This is analogous to the angular momentum of an object that is spinning around its center of mass, although strictly speaking these particles are believed to be point-like and cannot be said to be rotating. Spin is measured in units of the reduced Planck constant (ħ), with electrons, protons and neutrons all having spin ½ ħ, or "spin-½". In an atom, electrons in motion around the nucleus possess orbital angular momentum in addition to their spin, while the nucleus itself possesses angular momentum due to its nuclear spin. The magnetic field produced by an atom—its magnetic moment—is determined by these various forms of angular momentum, just as a rotating charged object classically produces a magnetic field, but the most dominant contribution comes from electron spin. Due to the nature of electrons to obey the Pauli exclusion principle, in which no two electrons may be found in the same quantum state, bound electrons pair up with each other, with one member of each pair in a spin up state and the other in the opposite, spin down state. Thus these spins cancel each other out, reducing the total magnetic dipole moment to zero in some atoms with even number of electrons. In ferromagnetic elements such as iron, cobalt and nickel, an odd number of electrons leads to an unpaired electron and a net overall magnetic moment. The orbitals of neighboring atoms overlap and a lower energy state is achieved when the spins of unpaired electrons are aligned with each other, a spontaneous process known as an exchange interaction. When the magnetic moments of ferromagnetic atoms are lined up, the material can produce a measurable macroscopic field.

Paramagnetic materials have atoms with magnetic moments that line up in random directions when no magnetic field is present, but the magnetic moments of the individual atoms line up in the presence of a field. The nucleus of an atom will have no spin when it has even numbers of both neutrons and protons, but for other cases of odd numbers, the nucleus may have a spin. Normally nuclei with spin are aligned in random directions because of thermal equilibrium, but for certain elements (such as xenon-129) it is possible to polarize a significant proportion of the nuclear spin states so that they are aligned in the same direction—a condition called hyperpolarization. This has important applications in magnetic resonance imaging. Energy levels The potential energy of an electron in an atom is negative relative to when the distance from the nucleus goes to infinity; its dependence on the electron's position reaches the minimum inside the nucleus, roughly in inverse proportion to the distance. In the quantum-mechanical model, a bound electron can occupy only a set of states centered on the nucleus, and each state corresponds to a specific energy level; see time-independent Schrödinger equation for a theoretical explanation. An energy level can be measured by the amount of energy needed to unbind the electron from the atom, and is usually given in units of electronvolts (eV). The lowest energy state of a bound electron is called the ground state, i.e. stationary state, while an electron transition to a higher level results in an excited state. The electron's energy increases along with n because the (average) distance to the nucleus increases. Dependence of the energy on is caused not by the electrostatic potential of the nucleus, but by interaction between electrons. For an electron to transition between two different states, e.g. ground state to first excited state, it must absorb or emit a photon at an energy matching the difference in the potential energy of those levels, according to the Niels Bohr model, what can be precisely calculated by the Schrödinger equation. Electrons jump between orbitals in a particle-like fashion. For example, if a single photon strikes the electrons, only a single electron changes states in response to the photon; see Electron properties. The energy of an emitted photon is proportional to its frequency, so these specific energy levels appear as distinct bands in the electromagnetic spectrum. Each element has a characteristic spectrum that can depend on the nuclear charge, subshells filled by electrons, the electromagnetic interactions between the electrons and other factors. When a continuous spectrum of energy is passed through a gas or plasma, some of the photons are absorbed by atoms, causing electrons to change their energy level. Those excited electrons that remain bound to their atom spontaneously emit this energy as a photon, traveling in a random direction, and so drop back to lower energy levels. Thus the atoms behave like a filter that forms a series of dark absorption bands in the energy output.

Paramagnetic materials have atoms with magnetic moments that line up in random directions when no magnetic field is present, but the magnetic moments of the individual atoms line up in the presence of a field. The nucleus of an atom will have no spin when it has even numbers of both neutrons and protons, but for other cases of odd numbers, the nucleus may have a spin. Normally nuclei with spin are aligned in random directions because of thermal equilibrium, but for certain elements (such as xenon-129) it is possible to polarize a significant proportion of the nuclear spin states so that they are aligned in the same direction—a condition called hyperpolarization. This has important applications in magnetic resonance imaging. Energy levels The potential energy of an electron in an atom is negative relative to when the distance from the nucleus goes to infinity; its dependence on the electron's position reaches the minimum inside the nucleus, roughly in inverse proportion to the distance. In the quantum-mechanical model, a bound electron can occupy only a set of states centered on the nucleus, and each state corresponds to a specific energy level; see time-independent Schrödinger equation for a theoretical explanation. An energy level can be measured by the amount of energy needed to unbind the electron from the atom, and is usually given in units of electronvolts (eV). The lowest energy state of a bound electron is called the ground state, i.e. stationary state, while an electron transition to a higher level results in an excited state. The electron's energy increases along with n because the (average) distance to the nucleus increases. Dependence of the energy on is caused not by the electrostatic potential of the nucleus, but by interaction between electrons. For an electron to transition between two different states, e.g. ground state to first excited state, it must absorb or emit a photon at an energy matching the difference in the potential energy of those levels, according to the Niels Bohr model, what can be precisely calculated by the Schrödinger equation. Electrons jump between orbitals in a particle-like fashion. For example, if a single photon strikes the electrons, only a single electron changes states in response to the photon; see Electron properties. The energy of an emitted photon is proportional to its frequency, so these specific energy levels appear as distinct bands in the electromagnetic spectrum. Each element has a characteristic spectrum that can depend on the nuclear charge, subshells filled by electrons, the electromagnetic interactions between the electrons and other factors. When a continuous spectrum of energy is passed through a gas or plasma, some of the photons are absorbed by atoms, causing electrons to change their energy level. Those excited electrons that remain bound to their atom spontaneously emit this energy as a photon, traveling in a random direction, and so drop back to lower energy levels. Thus the atoms behave like a filter that forms a series of dark absorption bands in the energy output.

Paramagnetic materials have atoms with magnetic moments that line up in random directions when no magnetic field is present, but the magnetic moments of the individual atoms line up in the presence of a field. The nucleus of an atom will have no spin when it has even numbers of both neutrons and protons, but for other cases of odd numbers, the nucleus may have a spin. Normally nuclei with spin are aligned in random directions because of thermal equilibrium, but for certain elements (such as xenon-129) it is possible to polarize a significant proportion of the nuclear spin states so that they are aligned in the same direction—a condition called hyperpolarization. This has important applications in magnetic resonance imaging. Energy levels The potential energy of an electron in an atom is negative relative to when the distance from the nucleus goes to infinity; its dependence on the electron's position reaches the minimum inside the nucleus, roughly in inverse proportion to the distance. In the quantum-mechanical model, a bound electron can occupy only a set of states centered on the nucleus, and each state corresponds to a specific energy level; see time-independent Schrödinger equation for a theoretical explanation. An energy level can be measured by the amount of energy needed to unbind the electron from the atom, and is usually given in units of electronvolts (eV). The lowest energy state of a bound electron is called the ground state, i.e. stationary state, while an electron transition to a higher level results in an excited state. The electron's energy increases along with n because the (average) distance to the nucleus increases. Dependence of the energy on is caused not by the electrostatic potential of the nucleus, but by interaction between electrons. For an electron to transition between two different states, e.g. ground state to first excited state, it must absorb or emit a photon at an energy matching the difference in the potential energy of those levels, according to the Niels Bohr model, what can be precisely calculated by the Schrödinger equation. Electrons jump between orbitals in a particle-like fashion. For example, if a single photon strikes the electrons, only a single electron changes states in response to the photon; see Electron properties. The energy of an emitted photon is proportional to its frequency, so these specific energy levels appear as distinct bands in the electromagnetic spectrum. Each element has a characteristic spectrum that can depend on the nuclear charge, subshells filled by electrons, the electromagnetic interactions between the electrons and other factors. When a continuous spectrum of energy is passed through a gas or plasma, some of the photons are absorbed by atoms, causing electrons to change their energy level. Those excited electrons that remain bound to their atom spontaneously emit this energy as a photon, traveling in a random direction, and so drop back to lower energy levels. Thus the atoms behave like a filter that forms a series of dark absorption bands in the energy output.

(An observer viewing the atoms from a view that does not include the continuous spectrum in the background, instead sees a series of emission lines from the photons emitted by the atoms.) Spectroscopic measurements of the strength and width of atomic spectral lines allow the composition and physical properties of a substance to be determined. Close examination of the spectral lines reveals that some display a fine structure splitting. This occurs because of spin-orbit coupling, which is an interaction between the spin and motion of the outermost electron. When an atom is in an external magnetic field, spectral lines become split into three or more components; a phenomenon called the Zeeman effect. This is caused by the interaction of the magnetic field with the magnetic moment of the atom and its electrons. Some atoms can have multiple electron configurations with the same energy level, which thus appear as a single spectral line. The interaction of the magnetic field with the atom shifts these electron configurations to slightly different energy levels, resulting in multiple spectral lines. The presence of an external electric field can cause a comparable splitting and shifting of spectral lines by modifying the electron energy levels, a phenomenon called the Stark effect. If a bound electron is in an excited state, an interacting photon with the proper energy can cause stimulated emission of a photon with a matching energy level. For this to occur, the electron must drop to a lower energy state that has an energy difference matching the energy of the interacting photon. The emitted photon and the interacting photon then move off in parallel and with matching phases. That is, the wave patterns of the two photons are synchronized. This physical property is used to make lasers, which can emit a coherent beam of light energy in a narrow frequency band. Valence and bonding behavior Valency is the combining power of an element. It is determined by the number of bonds it can form to other atoms or groups. The outermost electron shell of an atom in its uncombined state is known as the valence shell, and the electrons in that shell are called valence electrons. The number of valence electrons determines the bonding behavior with other atoms. Atoms tend to chemically react with each other in a manner that fills (or empties) their outer valence shells. For example, a transfer of a single electron between atoms is a useful approximation for bonds that form between atoms with one-electron more than a filled shell, and others that are one-electron short of a full shell, such as occurs in the compound sodium chloride and other chemical ionic salts. Many elements display multiple valences, or tendencies to share differing numbers of electrons in different compounds. Thus, chemical bonding between these elements takes many forms of electron-sharing that are more than simple electron transfers. Examples include the element carbon and the organic compounds.

(An observer viewing the atoms from a view that does not include the continuous spectrum in the background, instead sees a series of emission lines from the photons emitted by the atoms.) Spectroscopic measurements of the strength and width of atomic spectral lines allow the composition and physical properties of a substance to be determined. Close examination of the spectral lines reveals that some display a fine structure splitting. This occurs because of spin-orbit coupling, which is an interaction between the spin and motion of the outermost electron. When an atom is in an external magnetic field, spectral lines become split into three or more components; a phenomenon called the Zeeman effect. This is caused by the interaction of the magnetic field with the magnetic moment of the atom and its electrons. Some atoms can have multiple electron configurations with the same energy level, which thus appear as a single spectral line. The interaction of the magnetic field with the atom shifts these electron configurations to slightly different energy levels, resulting in multiple spectral lines. The presence of an external electric field can cause a comparable splitting and shifting of spectral lines by modifying the electron energy levels, a phenomenon called the Stark effect. If a bound electron is in an excited state, an interacting photon with the proper energy can cause stimulated emission of a photon with a matching energy level. For this to occur, the electron must drop to a lower energy state that has an energy difference matching the energy of the interacting photon. The emitted photon and the interacting photon then move off in parallel and with matching phases. That is, the wave patterns of the two photons are synchronized. This physical property is used to make lasers, which can emit a coherent beam of light energy in a narrow frequency band. Valence and bonding behavior Valency is the combining power of an element. It is determined by the number of bonds it can form to other atoms or groups. The outermost electron shell of an atom in its uncombined state is known as the valence shell, and the electrons in that shell are called valence electrons. The number of valence electrons determines the bonding behavior with other atoms. Atoms tend to chemically react with each other in a manner that fills (or empties) their outer valence shells. For example, a transfer of a single electron between atoms is a useful approximation for bonds that form between atoms with one-electron more than a filled shell, and others that are one-electron short of a full shell, such as occurs in the compound sodium chloride and other chemical ionic salts. Many elements display multiple valences, or tendencies to share differing numbers of electrons in different compounds. Thus, chemical bonding between these elements takes many forms of electron-sharing that are more than simple electron transfers. Examples include the element carbon and the organic compounds.

(An observer viewing the atoms from a view that does not include the continuous spectrum in the background, instead sees a series of emission lines from the photons emitted by the atoms.) Spectroscopic measurements of the strength and width of atomic spectral lines allow the composition and physical properties of a substance to be determined. Close examination of the spectral lines reveals that some display a fine structure splitting. This occurs because of spin-orbit coupling, which is an interaction between the spin and motion of the outermost electron. When an atom is in an external magnetic field, spectral lines become split into three or more components; a phenomenon called the Zeeman effect. This is caused by the interaction of the magnetic field with the magnetic moment of the atom and its electrons. Some atoms can have multiple electron configurations with the same energy level, which thus appear as a single spectral line. The interaction of the magnetic field with the atom shifts these electron configurations to slightly different energy levels, resulting in multiple spectral lines. The presence of an external electric field can cause a comparable splitting and shifting of spectral lines by modifying the electron energy levels, a phenomenon called the Stark effect. If a bound electron is in an excited state, an interacting photon with the proper energy can cause stimulated emission of a photon with a matching energy level. For this to occur, the electron must drop to a lower energy state that has an energy difference matching the energy of the interacting photon. The emitted photon and the interacting photon then move off in parallel and with matching phases. That is, the wave patterns of the two photons are synchronized. This physical property is used to make lasers, which can emit a coherent beam of light energy in a narrow frequency band. Valence and bonding behavior Valency is the combining power of an element. It is determined by the number of bonds it can form to other atoms or groups. The outermost electron shell of an atom in its uncombined state is known as the valence shell, and the electrons in that shell are called valence electrons. The number of valence electrons determines the bonding behavior with other atoms. Atoms tend to chemically react with each other in a manner that fills (or empties) their outer valence shells. For example, a transfer of a single electron between atoms is a useful approximation for bonds that form between atoms with one-electron more than a filled shell, and others that are one-electron short of a full shell, such as occurs in the compound sodium chloride and other chemical ionic salts. Many elements display multiple valences, or tendencies to share differing numbers of electrons in different compounds. Thus, chemical bonding between these elements takes many forms of electron-sharing that are more than simple electron transfers. Examples include the element carbon and the organic compounds.

The chemical elements are often displayed in a periodic table that is laid out to display recurring chemical properties, and elements with the same number of valence electrons form a group that is aligned in the same column of the table. (The horizontal rows correspond to the filling of a quantum shell of electrons.) The elements at the far right of the table have their outer shell completely filled with electrons, which results in chemically inert elements known as the noble gases. States Quantities of atoms are found in different states of matter that depend on the physical conditions, such as temperature and pressure. By varying the conditions, materials can transition between solids, liquids, gases and plasmas. Within a state, a material can also exist in different allotropes. An example of this is solid carbon, which can exist as graphite or diamond. Gaseous allotropes exist as well, such as dioxygen and ozone. At temperatures close to absolute zero, atoms can form a Bose–Einstein condensate, at which point quantum mechanical effects, which are normally only observed at the atomic scale, become apparent on a macroscopic scale. This super-cooled collection of atoms then behaves as a single super atom, which may allow fundamental checks of quantum mechanical behavior. Identification While atoms are too small to be seen, devices such as the scanning tunneling microscope (STM) enable their visualization at the surfaces of solids. The microscope uses the quantum tunneling phenomenon, which allows particles to pass through a barrier that would be insurmountable in the classical perspective. Electrons tunnel through the vacuum between two biased electrodes, providing a tunneling current that is exponentially dependent on their separation. One electrode is a sharp tip ideally ending with a single atom. At each point of the scan of the surface the tip's height is adjusted so as to keep the tunneling current at a set value. How much the tip moves to and away from the surface is interpreted as the height profile. For low bias, the microscope images the averaged electron orbitals across closely packed energy levels—the local density of the electronic states near the Fermi level. Because of the distances involved, both electrodes need to be extremely stable; only then periodicities can be observed that correspond to individual atoms. The method alone is not chemically specific, and cannot identify the atomic species present at the surface. Atoms can be easily identified by their mass. If an atom is ionized by removing one of its electrons, its trajectory when it passes through a magnetic field will bend. The radius by which the trajectory of a moving ion is turned by the magnetic field is determined by the mass of the atom. The mass spectrometer uses this principle to measure the mass-to-charge ratio of ions. If a sample contains multiple isotopes, the mass spectrometer can determine the proportion of each isotope in the sample by measuring the intensity of the different beams of ions.

The chemical elements are often displayed in a periodic table that is laid out to display recurring chemical properties, and elements with the same number of valence electrons form a group that is aligned in the same column of the table. (The horizontal rows correspond to the filling of a quantum shell of electrons.) The elements at the far right of the table have their outer shell completely filled with electrons, which results in chemically inert elements known as the noble gases. States Quantities of atoms are found in different states of matter that depend on the physical conditions, such as temperature and pressure. By varying the conditions, materials can transition between solids, liquids, gases and plasmas. Within a state, a material can also exist in different allotropes. An example of this is solid carbon, which can exist as graphite or diamond. Gaseous allotropes exist as well, such as dioxygen and ozone. At temperatures close to absolute zero, atoms can form a Bose–Einstein condensate, at which point quantum mechanical effects, which are normally only observed at the atomic scale, become apparent on a macroscopic scale. This super-cooled collection of atoms then behaves as a single super atom, which may allow fundamental checks of quantum mechanical behavior. Identification While atoms are too small to be seen, devices such as the scanning tunneling microscope (STM) enable their visualization at the surfaces of solids. The microscope uses the quantum tunneling phenomenon, which allows particles to pass through a barrier that would be insurmountable in the classical perspective. Electrons tunnel through the vacuum between two biased electrodes, providing a tunneling current that is exponentially dependent on their separation. One electrode is a sharp tip ideally ending with a single atom. At each point of the scan of the surface the tip's height is adjusted so as to keep the tunneling current at a set value. How much the tip moves to and away from the surface is interpreted as the height profile. For low bias, the microscope images the averaged electron orbitals across closely packed energy levels—the local density of the electronic states near the Fermi level. Because of the distances involved, both electrodes need to be extremely stable; only then periodicities can be observed that correspond to individual atoms. The method alone is not chemically specific, and cannot identify the atomic species present at the surface. Atoms can be easily identified by their mass. If an atom is ionized by removing one of its electrons, its trajectory when it passes through a magnetic field will bend. The radius by which the trajectory of a moving ion is turned by the magnetic field is determined by the mass of the atom. The mass spectrometer uses this principle to measure the mass-to-charge ratio of ions. If a sample contains multiple isotopes, the mass spectrometer can determine the proportion of each isotope in the sample by measuring the intensity of the different beams of ions.

The chemical elements are often displayed in a periodic table that is laid out to display recurring chemical properties, and elements with the same number of valence electrons form a group that is aligned in the same column of the table. (The horizontal rows correspond to the filling of a quantum shell of electrons.) The elements at the far right of the table have their outer shell completely filled with electrons, which results in chemically inert elements known as the noble gases. States Quantities of atoms are found in different states of matter that depend on the physical conditions, such as temperature and pressure. By varying the conditions, materials can transition between solids, liquids, gases and plasmas. Within a state, a material can also exist in different allotropes. An example of this is solid carbon, which can exist as graphite or diamond. Gaseous allotropes exist as well, such as dioxygen and ozone. At temperatures close to absolute zero, atoms can form a Bose–Einstein condensate, at which point quantum mechanical effects, which are normally only observed at the atomic scale, become apparent on a macroscopic scale. This super-cooled collection of atoms then behaves as a single super atom, which may allow fundamental checks of quantum mechanical behavior. Identification While atoms are too small to be seen, devices such as the scanning tunneling microscope (STM) enable their visualization at the surfaces of solids. The microscope uses the quantum tunneling phenomenon, which allows particles to pass through a barrier that would be insurmountable in the classical perspective. Electrons tunnel through the vacuum between two biased electrodes, providing a tunneling current that is exponentially dependent on their separation. One electrode is a sharp tip ideally ending with a single atom. At each point of the scan of the surface the tip's height is adjusted so as to keep the tunneling current at a set value. How much the tip moves to and away from the surface is interpreted as the height profile. For low bias, the microscope images the averaged electron orbitals across closely packed energy levels—the local density of the electronic states near the Fermi level. Because of the distances involved, both electrodes need to be extremely stable; only then periodicities can be observed that correspond to individual atoms. The method alone is not chemically specific, and cannot identify the atomic species present at the surface. Atoms can be easily identified by their mass. If an atom is ionized by removing one of its electrons, its trajectory when it passes through a magnetic field will bend. The radius by which the trajectory of a moving ion is turned by the magnetic field is determined by the mass of the atom. The mass spectrometer uses this principle to measure the mass-to-charge ratio of ions. If a sample contains multiple isotopes, the mass spectrometer can determine the proportion of each isotope in the sample by measuring the intensity of the different beams of ions.

Techniques to vaporize atoms include inductively coupled plasma atomic emission spectroscopy and inductively coupled plasma mass spectrometry, both of which use a plasma to vaporize samples for analysis. The atom-probe tomograph has sub-nanometer resolution in 3-D and can chemically identify individual atoms using time-of-flight mass spectrometry. Electron emission techniques such as X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), which measure the binding energies of the core electrons, are used to identify the atomic species present in a sample in a non-destructive way. With proper focusing both can be made area-specific. Another such method is electron energy loss spectroscopy (EELS), which measures the energy loss of an electron beam within a transmission electron microscope when it interacts with a portion of a sample. Spectra of excited states can be used to analyze the atomic composition of distant stars. Specific light wavelengths contained in the observed light from stars can be separated out and related to the quantized transitions in free gas atoms. These colors can be replicated using a gas-discharge lamp containing the same element. Helium was discovered in this way in the spectrum of the Sun 23 years before it was found on Earth. Origin and current state Baryonic matter forms about 4% of the total energy density of the observable Universe, with an average density of about 0.25 particles/m3 (mostly protons and electrons). Within a galaxy such as the Milky Way, particles have a much higher concentration, with the density of matter in the interstellar medium (ISM) ranging from 105 to 109 atoms/m3. The Sun is believed to be inside the Local Bubble, so the density in the solar neighborhood is only about 103 atoms/m3. Stars form from dense clouds in the ISM, and the evolutionary processes of stars result in the steady enrichment of the ISM with elements more massive than hydrogen and helium. Up to 95% of the Milky Way's baryonic matter are concentrated inside stars, where conditions are unfavorable for atomic matter. The total baryonic mass is about 10% of the mass of the galaxy; the remainder of the mass is an unknown dark matter. High temperature inside stars makes most "atoms" fully ionized, that is, separates all electrons from the nuclei. In stellar remnants—with exception of their surface layers—an immense pressure make electron shells impossible. Formation Electrons are thought to exist in the Universe since early stages of the Big Bang. Atomic nuclei forms in nucleosynthesis reactions. In about three minutes Big Bang nucleosynthesis produced most of the helium, lithium, and deuterium in the Universe, and perhaps some of the beryllium and boron. Ubiquitousness and stability of atoms relies on their binding energy, which means that an atom has a lower energy than an unbound system of the nucleus and electrons. Where the temperature is much higher than ionization potential, the matter exists in the form of plasma—a gas of positively charged ions (possibly, bare nuclei) and electrons. When the temperature drops below the ionization potential, atoms become statistically favorable.

Techniques to vaporize atoms include inductively coupled plasma atomic emission spectroscopy and inductively coupled plasma mass spectrometry, both of which use a plasma to vaporize samples for analysis. The atom-probe tomograph has sub-nanometer resolution in 3-D and can chemically identify individual atoms using time-of-flight mass spectrometry. Electron emission techniques such as X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), which measure the binding energies of the core electrons, are used to identify the atomic species present in a sample in a non-destructive way. With proper focusing both can be made area-specific. Another such method is electron energy loss spectroscopy (EELS), which measures the energy loss of an electron beam within a transmission electron microscope when it interacts with a portion of a sample. Spectra of excited states can be used to analyze the atomic composition of distant stars. Specific light wavelengths contained in the observed light from stars can be separated out and related to the quantized transitions in free gas atoms. These colors can be replicated using a gas-discharge lamp containing the same element. Helium was discovered in this way in the spectrum of the Sun 23 years before it was found on Earth. Origin and current state Baryonic matter forms about 4% of the total energy density of the observable Universe, with an average density of about 0.25 particles/m3 (mostly protons and electrons). Within a galaxy such as the Milky Way, particles have a much higher concentration, with the density of matter in the interstellar medium (ISM) ranging from 105 to 109 atoms/m3. The Sun is believed to be inside the Local Bubble, so the density in the solar neighborhood is only about 103 atoms/m3. Stars form from dense clouds in the ISM, and the evolutionary processes of stars result in the steady enrichment of the ISM with elements more massive than hydrogen and helium. Up to 95% of the Milky Way's baryonic matter are concentrated inside stars, where conditions are unfavorable for atomic matter. The total baryonic mass is about 10% of the mass of the galaxy; the remainder of the mass is an unknown dark matter. High temperature inside stars makes most "atoms" fully ionized, that is, separates all electrons from the nuclei. In stellar remnants—with exception of their surface layers—an immense pressure make electron shells impossible. Formation Electrons are thought to exist in the Universe since early stages of the Big Bang. Atomic nuclei forms in nucleosynthesis reactions. In about three minutes Big Bang nucleosynthesis produced most of the helium, lithium, and deuterium in the Universe, and perhaps some of the beryllium and boron. Ubiquitousness and stability of atoms relies on their binding energy, which means that an atom has a lower energy than an unbound system of the nucleus and electrons. Where the temperature is much higher than ionization potential, the matter exists in the form of plasma—a gas of positively charged ions (possibly, bare nuclei) and electrons. When the temperature drops below the ionization potential, atoms become statistically favorable.

Techniques to vaporize atoms include inductively coupled plasma atomic emission spectroscopy and inductively coupled plasma mass spectrometry, both of which use a plasma to vaporize samples for analysis. The atom-probe tomograph has sub-nanometer resolution in 3-D and can chemically identify individual atoms using time-of-flight mass spectrometry. Electron emission techniques such as X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), which measure the binding energies of the core electrons, are used to identify the atomic species present in a sample in a non-destructive way. With proper focusing both can be made area-specific. Another such method is electron energy loss spectroscopy (EELS), which measures the energy loss of an electron beam within a transmission electron microscope when it interacts with a portion of a sample. Spectra of excited states can be used to analyze the atomic composition of distant stars. Specific light wavelengths contained in the observed light from stars can be separated out and related to the quantized transitions in free gas atoms. These colors can be replicated using a gas-discharge lamp containing the same element. Helium was discovered in this way in the spectrum of the Sun 23 years before it was found on Earth. Origin and current state Baryonic matter forms about 4% of the total energy density of the observable Universe, with an average density of about 0.25 particles/m3 (mostly protons and electrons). Within a galaxy such as the Milky Way, particles have a much higher concentration, with the density of matter in the interstellar medium (ISM) ranging from 105 to 109 atoms/m3. The Sun is believed to be inside the Local Bubble, so the density in the solar neighborhood is only about 103 atoms/m3. Stars form from dense clouds in the ISM, and the evolutionary processes of stars result in the steady enrichment of the ISM with elements more massive than hydrogen and helium. Up to 95% of the Milky Way's baryonic matter are concentrated inside stars, where conditions are unfavorable for atomic matter. The total baryonic mass is about 10% of the mass of the galaxy; the remainder of the mass is an unknown dark matter. High temperature inside stars makes most "atoms" fully ionized, that is, separates all electrons from the nuclei. In stellar remnants—with exception of their surface layers—an immense pressure make electron shells impossible. Formation Electrons are thought to exist in the Universe since early stages of the Big Bang. Atomic nuclei forms in nucleosynthesis reactions. In about three minutes Big Bang nucleosynthesis produced most of the helium, lithium, and deuterium in the Universe, and perhaps some of the beryllium and boron. Ubiquitousness and stability of atoms relies on their binding energy, which means that an atom has a lower energy than an unbound system of the nucleus and electrons. Where the temperature is much higher than ionization potential, the matter exists in the form of plasma—a gas of positively charged ions (possibly, bare nuclei) and electrons. When the temperature drops below the ionization potential, atoms become statistically favorable.

Atoms (complete with bound electrons) became to dominate over charged particles 380,000 years after the Big Bang—an epoch called recombination, when the expanding Universe cooled enough to allow electrons to become attached to nuclei. Since the Big Bang, which produced no carbon or heavier elements, atomic nuclei have been combined in stars through the process of nuclear fusion to produce more of the element helium, and (via the triple alpha process) the sequence of elements from carbon up to iron; see stellar nucleosynthesis for details. Isotopes such as lithium-6, as well as some beryllium and boron are generated in space through cosmic ray spallation. This occurs when a high-energy proton strikes an atomic nucleus, causing large numbers of nucleons to be ejected. Elements heavier than iron were produced in supernovae and colliding neutron stars through the r-process, and in AGB stars through the s-process, both of which involve the capture of neutrons by atomic nuclei. Elements such as lead formed largely through the radioactive decay of heavier elements. Earth Most of the atoms that make up the Earth and its inhabitants were present in their current form in the nebula that collapsed out of a molecular cloud to form the Solar System. The rest are the result of radioactive decay, and their relative proportion can be used to determine the age of the Earth through radiometric dating. Most of the helium in the crust of the Earth (about 99% of the helium from gas wells, as shown by its lower abundance of helium-3) is a product of alpha decay. There are a few trace atoms on Earth that were not present at the beginning (i.e., not "primordial"), nor are results of radioactive decay. Carbon-14 is continuously generated by cosmic rays in the atmosphere. Some atoms on Earth have been artificially generated either deliberately or as by-products of nuclear reactors or explosions. Of the transuranic elements—those with atomic numbers greater than 92—only plutonium and neptunium occur naturally on Earth. Transuranic elements have radioactive lifetimes shorter than the current age of the Earth and thus identifiable quantities of these elements have long since decayed, with the exception of traces of plutonium-244 possibly deposited by cosmic dust. Natural deposits of plutonium and neptunium are produced by neutron capture in uranium ore. The Earth contains approximately atoms. Although small numbers of independent atoms of noble gases exist, such as argon, neon, and helium, 99% of the atmosphere is bound in the form of molecules, including carbon dioxide and diatomic oxygen and nitrogen. At the surface of the Earth, an overwhelming majority of atoms combine to form various compounds, including water, salt, silicates and oxides. Atoms can also combine to create materials that do not consist of discrete molecules, including crystals and liquid or solid metals. This atomic matter forms networked arrangements that lack the particular type of small-scale interrupted order associated with molecular matter. Rare and theoretical forms Superheavy elements All nuclides with atomic numbers higher than 82 (lead) are known to be radioactive.

Atoms (complete with bound electrons) became to dominate over charged particles 380,000 years after the Big Bang—an epoch called recombination, when the expanding Universe cooled enough to allow electrons to become attached to nuclei. Since the Big Bang, which produced no carbon or heavier elements, atomic nuclei have been combined in stars through the process of nuclear fusion to produce more of the element helium, and (via the triple alpha process) the sequence of elements from carbon up to iron; see stellar nucleosynthesis for details. Isotopes such as lithium-6, as well as some beryllium and boron are generated in space through cosmic ray spallation. This occurs when a high-energy proton strikes an atomic nucleus, causing large numbers of nucleons to be ejected. Elements heavier than iron were produced in supernovae and colliding neutron stars through the r-process, and in AGB stars through the s-process, both of which involve the capture of neutrons by atomic nuclei. Elements such as lead formed largely through the radioactive decay of heavier elements. Earth Most of the atoms that make up the Earth and its inhabitants were present in their current form in the nebula that collapsed out of a molecular cloud to form the Solar System. The rest are the result of radioactive decay, and their relative proportion can be used to determine the age of the Earth through radiometric dating. Most of the helium in the crust of the Earth (about 99% of the helium from gas wells, as shown by its lower abundance of helium-3) is a product of alpha decay. There are a few trace atoms on Earth that were not present at the beginning (i.e., not "primordial"), nor are results of radioactive decay. Carbon-14 is continuously generated by cosmic rays in the atmosphere. Some atoms on Earth have been artificially generated either deliberately or as by-products of nuclear reactors or explosions. Of the transuranic elements—those with atomic numbers greater than 92—only plutonium and neptunium occur naturally on Earth. Transuranic elements have radioactive lifetimes shorter than the current age of the Earth and thus identifiable quantities of these elements have long since decayed, with the exception of traces of plutonium-244 possibly deposited by cosmic dust. Natural deposits of plutonium and neptunium are produced by neutron capture in uranium ore. The Earth contains approximately atoms. Although small numbers of independent atoms of noble gases exist, such as argon, neon, and helium, 99% of the atmosphere is bound in the form of molecules, including carbon dioxide and diatomic oxygen and nitrogen. At the surface of the Earth, an overwhelming majority of atoms combine to form various compounds, including water, salt, silicates and oxides. Atoms can also combine to create materials that do not consist of discrete molecules, including crystals and liquid or solid metals. This atomic matter forms networked arrangements that lack the particular type of small-scale interrupted order associated with molecular matter. Rare and theoretical forms Superheavy elements All nuclides with atomic numbers higher than 82 (lead) are known to be radioactive.

Atoms (complete with bound electrons) became to dominate over charged particles 380,000 years after the Big Bang—an epoch called recombination, when the expanding Universe cooled enough to allow electrons to become attached to nuclei. Since the Big Bang, which produced no carbon or heavier elements, atomic nuclei have been combined in stars through the process of nuclear fusion to produce more of the element helium, and (via the triple alpha process) the sequence of elements from carbon up to iron; see stellar nucleosynthesis for details. Isotopes such as lithium-6, as well as some beryllium and boron are generated in space through cosmic ray spallation. This occurs when a high-energy proton strikes an atomic nucleus, causing large numbers of nucleons to be ejected. Elements heavier than iron were produced in supernovae and colliding neutron stars through the r-process, and in AGB stars through the s-process, both of which involve the capture of neutrons by atomic nuclei. Elements such as lead formed largely through the radioactive decay of heavier elements. Earth Most of the atoms that make up the Earth and its inhabitants were present in their current form in the nebula that collapsed out of a molecular cloud to form the Solar System. The rest are the result of radioactive decay, and their relative proportion can be used to determine the age of the Earth through radiometric dating. Most of the helium in the crust of the Earth (about 99% of the helium from gas wells, as shown by its lower abundance of helium-3) is a product of alpha decay. There are a few trace atoms on Earth that were not present at the beginning (i.e., not "primordial"), nor are results of radioactive decay. Carbon-14 is continuously generated by cosmic rays in the atmosphere. Some atoms on Earth have been artificially generated either deliberately or as by-products of nuclear reactors or explosions. Of the transuranic elements—those with atomic numbers greater than 92—only plutonium and neptunium occur naturally on Earth. Transuranic elements have radioactive lifetimes shorter than the current age of the Earth and thus identifiable quantities of these elements have long since decayed, with the exception of traces of plutonium-244 possibly deposited by cosmic dust. Natural deposits of plutonium and neptunium are produced by neutron capture in uranium ore. The Earth contains approximately atoms. Although small numbers of independent atoms of noble gases exist, such as argon, neon, and helium, 99% of the atmosphere is bound in the form of molecules, including carbon dioxide and diatomic oxygen and nitrogen. At the surface of the Earth, an overwhelming majority of atoms combine to form various compounds, including water, salt, silicates and oxides. Atoms can also combine to create materials that do not consist of discrete molecules, including crystals and liquid or solid metals. This atomic matter forms networked arrangements that lack the particular type of small-scale interrupted order associated with molecular matter. Rare and theoretical forms Superheavy elements All nuclides with atomic numbers higher than 82 (lead) are known to be radioactive.

No nuclide with an atomic number exceeding 92 (uranium) exists on Earth as a primordial nuclide, and heavier elements generally have shorter half-lives. Nevertheless, an "island of stability" encompassing relatively long-lived isotopes of superheavy elements with atomic numbers 110 to 114 might exist. Predictions for the half-life of the most stable nuclide on the island range from a few minutes to millions of years. In any case, superheavy elements (with Z > 104) would not exist due to increasing Coulomb repulsion (which results in spontaneous fission with increasingly short half-lives) in the absence of any stabilizing effects. Exotic matter Each particle of matter has a corresponding antimatter particle with the opposite electrical charge. Thus, the positron is a positively charged antielectron and the antiproton is a negatively charged equivalent of a proton. When a matter and corresponding antimatter particle meet, they annihilate each other. Because of this, along with an imbalance between the number of matter and antimatter particles, the latter are rare in the universe. The first causes of this imbalance are not yet fully understood, although theories of baryogenesis may offer an explanation. As a result, no antimatter atoms have been discovered in nature. In 1996, the antimatter counterpart of the hydrogen atom (antihydrogen) was synthesized at the CERN laboratory in Geneva. Other exotic atoms have been created by replacing one of the protons, neutrons or electrons with other particles that have the same charge. For example, an electron can be replaced by a more massive muon, forming a muonic atom. These types of atoms can be used to test fundamental predictions of physics. See also Notes References Bibliography Further reading External links Chemistry Articles containing video clips

No nuclide with an atomic number exceeding 92 (uranium) exists on Earth as a primordial nuclide, and heavier elements generally have shorter half-lives. Nevertheless, an "island of stability" encompassing relatively long-lived isotopes of superheavy elements with atomic numbers 110 to 114 might exist. Predictions for the half-life of the most stable nuclide on the island range from a few minutes to millions of years. In any case, superheavy elements (with Z > 104) would not exist due to increasing Coulomb repulsion (which results in spontaneous fission with increasingly short half-lives) in the absence of any stabilizing effects. Exotic matter Each particle of matter has a corresponding antimatter particle with the opposite electrical charge. Thus, the positron is a positively charged antielectron and the antiproton is a negatively charged equivalent of a proton. When a matter and corresponding antimatter particle meet, they annihilate each other. Because of this, along with an imbalance between the number of matter and antimatter particles, the latter are rare in the universe. The first causes of this imbalance are not yet fully understood, although theories of baryogenesis may offer an explanation. As a result, no antimatter atoms have been discovered in nature. In 1996, the antimatter counterpart of the hydrogen atom (antihydrogen) was synthesized at the CERN laboratory in Geneva. Other exotic atoms have been created by replacing one of the protons, neutrons or electrons with other particles that have the same charge. For example, an electron can be replaced by a more massive muon, forming a muonic atom. These types of atoms can be used to test fundamental predictions of physics. See also Notes References Bibliography Further reading External links Chemistry Articles containing video clips

No nuclide with an atomic number exceeding 92 (uranium) exists on Earth as a primordial nuclide, and heavier elements generally have shorter half-lives. Nevertheless, an "island of stability" encompassing relatively long-lived isotopes of superheavy elements with atomic numbers 110 to 114 might exist. Predictions for the half-life of the most stable nuclide on the island range from a few minutes to millions of years. In any case, superheavy elements (with Z > 104) would not exist due to increasing Coulomb repulsion (which results in spontaneous fission with increasingly short half-lives) in the absence of any stabilizing effects. Exotic matter Each particle of matter has a corresponding antimatter particle with the opposite electrical charge. Thus, the positron is a positively charged antielectron and the antiproton is a negatively charged equivalent of a proton. When a matter and corresponding antimatter particle meet, they annihilate each other. Because of this, along with an imbalance between the number of matter and antimatter particles, the latter are rare in the universe. The first causes of this imbalance are not yet fully understood, although theories of baryogenesis may offer an explanation. As a result, no antimatter atoms have been discovered in nature. In 1996, the antimatter counterpart of the hydrogen atom (antihydrogen) was synthesized at the CERN laboratory in Geneva. Other exotic atoms have been created by replacing one of the protons, neutrons or electrons with other particles that have the same charge. For example, an electron can be replaced by a more massive muon, forming a muonic atom. These types of atoms can be used to test fundamental predictions of physics. See also Notes References Bibliography Further reading External links Chemistry Articles containing video clips

Arable land Arable land (from the , "able to be ploughed") is any land capable of being ploughed and used to grow crops. Alternatively, for the purposes of agricultural statistics, the term often has a more precise definition: A more concise definition appearing in the Eurostat glossary similarly refers to actual rather than potential uses: "land worked (ploughed or tilled) regularly, generally under a system of crop rotation". Non-arable land can sometimes be converted to arable land through methods such as loosening and tilling (breaking up) of the soil, though in more extreme cases the degree of modification required to make certain types of land arable can become prohibitively expensive. In Britain, arable land has traditionally been contrasted with pasturable land such as heaths, which could be used for sheep-rearing but not as farmland. Arable land area According to the Food and Agriculture Organization of the United Nations, in 2013, the world's arable land amounted to 1.407 billion hectares, out of a total of 4.924 billion hectares of land used for agriculture. Arable land (hectares per person) Non-arable land Agricultural land that is not arable according to the FAO definition above includes: Meadows and pasturesland used as pasture and grazed range, and those natural grasslands and sedge meadows that are used for hay production in some regions. Permanent cropland that produces crops from woody vegetation, e.g. orchard land, vineyards, coffee plantations, rubber plantations, and land producing nut trees; Other non-arable land includes land that is not suitable for any agricultural use. Land that is not arable, in the sense of lacking capability or suitability for cultivation for crop production, has one or more limitationsa lack of sufficient freshwater for irrigation, stoniness, steepness, adverse climate, excessive wetness with the impracticality of drainage, excessive salts, or a combination of these, among others. Although such limitations may preclude cultivation, and some will in some cases preclude any agricultural use, large areas unsuitable for cultivation may still be agriculturally productive. For example, United States NRCS statistics indicate that about 59 percent of US non-federal pasture and unforested rangeland is unsuitable for cultivation, yet such land has value for grazing of livestock. In British Columbia, Canada, 41 percent of the provincial Agricultural Land Reserve area is unsuitable for the production of cultivated crops, but is suitable for uncultivated production of forage usable by grazing livestock. Similar examples can be found in many rangeland areas elsewhere. Land incapable of being cultivated for the production of crops can sometimes be converted to arable land. New arable land makes more food and can reduce starvation. This outcome also makes a country more self-sufficient and politically independent, because food importation is reduced.

Arable land Arable land (from the , "able to be ploughed") is any land capable of being ploughed and used to grow crops. Alternatively, for the purposes of agricultural statistics, the term often has a more precise definition: A more concise definition appearing in the Eurostat glossary similarly refers to actual rather than potential uses: "land worked (ploughed or tilled) regularly, generally under a system of crop rotation". Non-arable land can sometimes be converted to arable land through methods such as loosening and tilling (breaking up) of the soil, though in more extreme cases the degree of modification required to make certain types of land arable can become prohibitively expensive. In Britain, arable land has traditionally been contrasted with pasturable land such as heaths, which could be used for sheep-rearing but not as farmland. Arable land area According to the Food and Agriculture Organization of the United Nations, in 2013, the world's arable land amounted to 1.407 billion hectares, out of a total of 4.924 billion hectares of land used for agriculture. Arable land (hectares per person) Non-arable land Agricultural land that is not arable according to the FAO definition above includes: Meadows and pasturesland used as pasture and grazed range, and those natural grasslands and sedge meadows that are used for hay production in some regions. Permanent cropland that produces crops from woody vegetation, e.g. orchard land, vineyards, coffee plantations, rubber plantations, and land producing nut trees; Other non-arable land includes land that is not suitable for any agricultural use. Land that is not arable, in the sense of lacking capability or suitability for cultivation for crop production, has one or more limitationsa lack of sufficient freshwater for irrigation, stoniness, steepness, adverse climate, excessive wetness with the impracticality of drainage, excessive salts, or a combination of these, among others. Although such limitations may preclude cultivation, and some will in some cases preclude any agricultural use, large areas unsuitable for cultivation may still be agriculturally productive. For example, United States NRCS statistics indicate that about 59 percent of US non-federal pasture and unforested rangeland is unsuitable for cultivation, yet such land has value for grazing of livestock. In British Columbia, Canada, 41 percent of the provincial Agricultural Land Reserve area is unsuitable for the production of cultivated crops, but is suitable for uncultivated production of forage usable by grazing livestock. Similar examples can be found in many rangeland areas elsewhere. Land incapable of being cultivated for the production of crops can sometimes be converted to arable land. New arable land makes more food and can reduce starvation. This outcome also makes a country more self-sufficient and politically independent, because food importation is reduced.

Making non-arable land arable often involves digging new irrigation canals and new wells, aqueducts, desalination plants, planting trees for shade in the desert, hydroponics, fertilizer, nitrogen fertilizer, pesticides, reverse osmosis water processors, PET film insulation or other insulation against heat and cold, digging ditches and hills for protection against the wind, and installing greenhouses with internal light and heat for protection against the cold outside and to provide light in cloudy areas. Such modifications are often prohibitively expensive. An alternative is the seawater greenhouse, which desalinates water through evaporation and condensation using solar energy as the only energy input. This technology is optimized to grow crops on desert land close to the sea. The use of artifices does not make the land arable. Rock still remains rock, and shallowless than turnable soil is still not considered toilable. The use of artifice is an open-air none recycled water hydroponics relationship. The below described circumstances are not in perspective, have limited duration, and have a tendency to accumulate trace materials in soil that either there or elsewhere cause deoxygenation. The use of vast amounts of fertilizer may have unintended consequences for the environment by devastating rivers, waterways, and river endings through the accumulation of non-degradable toxins and nitrogen-bearing molecules that remove oxygen and cause non-aerobic processes to form. Examples of infertile non-arable land being turned into fertile arable land include: Aran Islands: These islands off the west coast of Ireland (not to be confused with the Isle of Arran in Scotland's Firth of Clyde) were unsuitable for arable farming because they were too rocky. The people covered the islands with a shallow layer of seaweed and sand from the ocean. Today, crops are grown there, even though the islands are still considered non-arable. Israel: The construction of desalination plants along Israel's coast allowed agriculture in some areas that were formerly desert. The desalination plants, which remove the salt from ocean water, have produced a new source of water for farming, drinking, and washing. Slash and burn agriculture uses nutrients in wood ash, but these expire within a few years. Terra preta, fertile tropical soils produced by adding charcoal. Examples of fertile arable land being turned into infertile land include: Droughts such as the "Dust Bowl" of the Great Depression in the US turned farmland into desert. Each year, arable land is lost due to desertification and human-induced erosion. Improper irrigation of farmland can wick the sodium, calcium, and magnesium from the soil and water to the surface. This process steadily concentrates salt in the root zone, decreasing productivity for crops that are not salt-tolerant. Rainforest deforestation: The fertile tropical forests are converted into infertile desert land. For example, Madagascar's central highland plateau has become virtually totally barren (about ten percent of the country) as a result of slash-and-burn deforestation, an element of shifting cultivation practiced by many natives.

Making non-arable land arable often involves digging new irrigation canals and new wells, aqueducts, desalination plants, planting trees for shade in the desert, hydroponics, fertilizer, nitrogen fertilizer, pesticides, reverse osmosis water processors, PET film insulation or other insulation against heat and cold, digging ditches and hills for protection against the wind, and installing greenhouses with internal light and heat for protection against the cold outside and to provide light in cloudy areas. Such modifications are often prohibitively expensive. An alternative is the seawater greenhouse, which desalinates water through evaporation and condensation using solar energy as the only energy input. This technology is optimized to grow crops on desert land close to the sea. The use of artifices does not make the land arable. Rock still remains rock, and shallowless than turnable soil is still not considered toilable. The use of artifice is an open-air none recycled water hydroponics relationship. The below described circumstances are not in perspective, have limited duration, and have a tendency to accumulate trace materials in soil that either there or elsewhere cause deoxygenation. The use of vast amounts of fertilizer may have unintended consequences for the environment by devastating rivers, waterways, and river endings through the accumulation of non-degradable toxins and nitrogen-bearing molecules that remove oxygen and cause non-aerobic processes to form. Examples of infertile non-arable land being turned into fertile arable land include: Aran Islands: These islands off the west coast of Ireland (not to be confused with the Isle of Arran in Scotland's Firth of Clyde) were unsuitable for arable farming because they were too rocky. The people covered the islands with a shallow layer of seaweed and sand from the ocean. Today, crops are grown there, even though the islands are still considered non-arable. Israel: The construction of desalination plants along Israel's coast allowed agriculture in some areas that were formerly desert. The desalination plants, which remove the salt from ocean water, have produced a new source of water for farming, drinking, and washing. Slash and burn agriculture uses nutrients in wood ash, but these expire within a few years. Terra preta, fertile tropical soils produced by adding charcoal. Examples of fertile arable land being turned into infertile land include: Droughts such as the "Dust Bowl" of the Great Depression in the US turned farmland into desert. Each year, arable land is lost due to desertification and human-induced erosion. Improper irrigation of farmland can wick the sodium, calcium, and magnesium from the soil and water to the surface. This process steadily concentrates salt in the root zone, decreasing productivity for crops that are not salt-tolerant. Rainforest deforestation: The fertile tropical forests are converted into infertile desert land. For example, Madagascar's central highland plateau has become virtually totally barren (about ten percent of the country) as a result of slash-and-burn deforestation, an element of shifting cultivation practiced by many natives.

Making non-arable land arable often involves digging new irrigation canals and new wells, aqueducts, desalination plants, planting trees for shade in the desert, hydroponics, fertilizer, nitrogen fertilizer, pesticides, reverse osmosis water processors, PET film insulation or other insulation against heat and cold, digging ditches and hills for protection against the wind, and installing greenhouses with internal light and heat for protection against the cold outside and to provide light in cloudy areas. Such modifications are often prohibitively expensive. An alternative is the seawater greenhouse, which desalinates water through evaporation and condensation using solar energy as the only energy input. This technology is optimized to grow crops on desert land close to the sea. The use of artifices does not make the land arable. Rock still remains rock, and shallowless than turnable soil is still not considered toilable. The use of artifice is an open-air none recycled water hydroponics relationship. The below described circumstances are not in perspective, have limited duration, and have a tendency to accumulate trace materials in soil that either there or elsewhere cause deoxygenation. The use of vast amounts of fertilizer may have unintended consequences for the environment by devastating rivers, waterways, and river endings through the accumulation of non-degradable toxins and nitrogen-bearing molecules that remove oxygen and cause non-aerobic processes to form. Examples of infertile non-arable land being turned into fertile arable land include: Aran Islands: These islands off the west coast of Ireland (not to be confused with the Isle of Arran in Scotland's Firth of Clyde) were unsuitable for arable farming because they were too rocky. The people covered the islands with a shallow layer of seaweed and sand from the ocean. Today, crops are grown there, even though the islands are still considered non-arable. Israel: The construction of desalination plants along Israel's coast allowed agriculture in some areas that were formerly desert. The desalination plants, which remove the salt from ocean water, have produced a new source of water for farming, drinking, and washing. Slash and burn agriculture uses nutrients in wood ash, but these expire within a few years. Terra preta, fertile tropical soils produced by adding charcoal. Examples of fertile arable land being turned into infertile land include: Droughts such as the "Dust Bowl" of the Great Depression in the US turned farmland into desert. Each year, arable land is lost due to desertification and human-induced erosion. Improper irrigation of farmland can wick the sodium, calcium, and magnesium from the soil and water to the surface. This process steadily concentrates salt in the root zone, decreasing productivity for crops that are not salt-tolerant. Rainforest deforestation: The fertile tropical forests are converted into infertile desert land. For example, Madagascar's central highland plateau has become virtually totally barren (about ten percent of the country) as a result of slash-and-burn deforestation, an element of shifting cultivation practiced by many natives.

See also Development easement Land use statistics by country List of environment topics Soil fertility References External links Article from Technorati on Shrinking Arable Farmland in the world Surface area of the Earth Agricultural land

See also Development easement Land use statistics by country List of environment topics Soil fertility References External links Article from Technorati on Shrinking Arable Farmland in the world Surface area of the Earth Agricultural land

See also Development easement Land use statistics by country List of environment topics Soil fertility References External links Article from Technorati on Shrinking Arable Farmland in the world Surface area of the Earth Agricultural land

Aluminium Aluminium (or aluminum in American English and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has a great affinity towards oxygen, and forms a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, non-magnetic and ductile. It has one stable isotope, 27Al; this isotope is very common, making aluminium the twelfth most common element in the Universe. The radioactivity of 26Al is used in radiodating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ is small and highly charged; as such, it is polarizing, and bonds aluminium forms tend towards covalency. The strong affinity towards oxygen leads to aluminium's common association with oxygen in nature in the form of oxides; for this reason, aluminium is found on Earth primarily in rocks in the crust, where it is the third most abundant element after oxygen and silicon, rather than in the mantle, and virtually never as the free metal. The discovery of aluminium was announced in 1825 by Danish physicist Hans Christian Ørsted. The first industrial production of aluminium was initiated by French chemist Henri Étienne Sainte-Claire Deville in 1856. Aluminium became much more available to the public with the Hall–Héroult process developed independently by French engineer Paul Héroult and American engineer Charles Martin Hall in 1886, and the mass production of aluminium led to its extensive use in industry and everyday life. In World Wars I and II, aluminium was a crucial strategic resource for aviation. In 1954, aluminium became the most produced non-ferrous metal, surpassing copper. In the 21st century, most aluminium was consumed in transportation, engineering, construction, and packaging in the United States, Western Europe, and Japan. Despite its prevalence in the environment, no living organism is known to use aluminium salts metabolically, but aluminium is well tolerated by plants and animals. Because of the abundance of these salts, the potential for a biological role for them is of continuing interest, and studies continue. Physical characteristics Isotopes Of aluminium isotopes, only is stable. This situation is common for elements with an odd atomic number. It is the only primordial aluminium isotope, i.e. the only one that has existed on Earth in its current form since the formation of the planet. Nearly all aluminium on Earth is present as this isotope, which makes it a mononuclidic element and means that its standard atomic weight is virtually the same as that of the isotope. This makes aluminium very useful in nuclear magnetic resonance (NMR), as its single stable isotope has a high NMR sensitivity. The standard atomic weight of aluminium is low in comparison with many other metals.

Aluminium Aluminium (or aluminum in American English and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has a great affinity towards oxygen, and forms a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, non-magnetic and ductile. It has one stable isotope, 27Al; this isotope is very common, making aluminium the twelfth most common element in the Universe. The radioactivity of 26Al is used in radiodating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ is small and highly charged; as such, it is polarizing, and bonds aluminium forms tend towards covalency. The strong affinity towards oxygen leads to aluminium's common association with oxygen in nature in the form of oxides; for this reason, aluminium is found on Earth primarily in rocks in the crust, where it is the third most abundant element after oxygen and silicon, rather than in the mantle, and virtually never as the free metal. The discovery of aluminium was announced in 1825 by Danish physicist Hans Christian Ørsted. The first industrial production of aluminium was initiated by French chemist Henri Étienne Sainte-Claire Deville in 1856. Aluminium became much more available to the public with the Hall–Héroult process developed independently by French engineer Paul Héroult and American engineer Charles Martin Hall in 1886, and the mass production of aluminium led to its extensive use in industry and everyday life. In World Wars I and II, aluminium was a crucial strategic resource for aviation. In 1954, aluminium became the most produced non-ferrous metal, surpassing copper. In the 21st century, most aluminium was consumed in transportation, engineering, construction, and packaging in the United States, Western Europe, and Japan. Despite its prevalence in the environment, no living organism is known to use aluminium salts metabolically, but aluminium is well tolerated by plants and animals. Because of the abundance of these salts, the potential for a biological role for them is of continuing interest, and studies continue. Physical characteristics Isotopes Of aluminium isotopes, only is stable. This situation is common for elements with an odd atomic number. It is the only primordial aluminium isotope, i.e. the only one that has existed on Earth in its current form since the formation of the planet. Nearly all aluminium on Earth is present as this isotope, which makes it a mononuclidic element and means that its standard atomic weight is virtually the same as that of the isotope. This makes aluminium very useful in nuclear magnetic resonance (NMR), as its single stable isotope has a high NMR sensitivity. The standard atomic weight of aluminium is low in comparison with many other metals.

All other isotopes of aluminium are radioactive. The most stable of these is 26Al: while it was present along with stable 27Al in the interstellar medium from which the Solar System formed, having been produced by stellar nucleosynthesis as well, its half-life is only 717,000 years and therefore a detectable amount has not survived since the formation of the planet. However, minute traces of 26Al are produced from argon in the atmosphere by spallation caused by cosmic ray protons. The ratio of 26Al to 10Be has been used for radiodating of geological processes over 105 to 106 year time scales, in particular transport, deposition, sediment storage, burial times, and erosion. Most meteorite scientists believe that the energy released by the decay of 26Al was responsible for the melting and differentiation of some asteroids after their formation 4.55 billion years ago. The remaining isotopes of aluminium, with mass numbers ranging from 22 to 43, all have half-lives well under an hour. Three metastable states are known, all with half-lives under a minute. Electron shell An aluminium atom has 13 electrons, arranged in an electron configuration of [Ne] 3s2 3p1, with three electrons beyond a stable noble gas configuration. Accordingly, the combined first three ionization energies of aluminium are far lower than the fourth ionization energy alone. Such an electron configuration is shared with the other well-characterized members of its group, boron, gallium, indium, and thallium; it is also expected for nihonium. Aluminium can relatively easily surrender its three outermost electrons in many chemical reactions (see below). The electronegativity of aluminium is 1.61 (Pauling scale). A free aluminium atom has a radius of 143 pm. With the three outermost electrons removed, the radius shrinks to 39 pm for a 4-coordinated atom or 53.5 pm for a 6-coordinated atom. At standard temperature and pressure, aluminium atoms (when not affected by atoms of other elements) form a face-centered cubic crystal system bound by metallic bonding provided by atoms' outermost electrons; hence aluminium (at these conditions) is a metal. This crystal system is shared by many other metals, such as lead and copper; the size of a unit cell of aluminium is comparable to that of those other metals. The system, however, is not shared by the other members of its group; boron has ionization energies too high to allow metallization, thallium has a hexagonal close-packed structure, and gallium and indium have unusual structures that are not close-packed like those of aluminium and thallium. The few electrons that are available for metallic bonding in aluminium metal are a probable cause for it being soft with a low melting point and low electrical resistivity. Bulk Aluminium metal has an appearance ranging from silvery white to dull gray, depending on the surface roughness. A fresh film of aluminium serves as a good reflector (approximately 92%) of visible light and an excellent reflector (as much as 98%) of medium and far infrared radiation.

All other isotopes of aluminium are radioactive. The most stable of these is 26Al: while it was present along with stable 27Al in the interstellar medium from which the Solar System formed, having been produced by stellar nucleosynthesis as well, its half-life is only 717,000 years and therefore a detectable amount has not survived since the formation of the planet. However, minute traces of 26Al are produced from argon in the atmosphere by spallation caused by cosmic ray protons. The ratio of 26Al to 10Be has been used for radiodating of geological processes over 105 to 106 year time scales, in particular transport, deposition, sediment storage, burial times, and erosion. Most meteorite scientists believe that the energy released by the decay of 26Al was responsible for the melting and differentiation of some asteroids after their formation 4.55 billion years ago. The remaining isotopes of aluminium, with mass numbers ranging from 22 to 43, all have half-lives well under an hour. Three metastable states are known, all with half-lives under a minute. Electron shell An aluminium atom has 13 electrons, arranged in an electron configuration of [Ne] 3s2 3p1, with three electrons beyond a stable noble gas configuration. Accordingly, the combined first three ionization energies of aluminium are far lower than the fourth ionization energy alone. Such an electron configuration is shared with the other well-characterized members of its group, boron, gallium, indium, and thallium; it is also expected for nihonium. Aluminium can relatively easily surrender its three outermost electrons in many chemical reactions (see below). The electronegativity of aluminium is 1.61 (Pauling scale). A free aluminium atom has a radius of 143 pm. With the three outermost electrons removed, the radius shrinks to 39 pm for a 4-coordinated atom or 53.5 pm for a 6-coordinated atom. At standard temperature and pressure, aluminium atoms (when not affected by atoms of other elements) form a face-centered cubic crystal system bound by metallic bonding provided by atoms' outermost electrons; hence aluminium (at these conditions) is a metal. This crystal system is shared by many other metals, such as lead and copper; the size of a unit cell of aluminium is comparable to that of those other metals. The system, however, is not shared by the other members of its group; boron has ionization energies too high to allow metallization, thallium has a hexagonal close-packed structure, and gallium and indium have unusual structures that are not close-packed like those of aluminium and thallium. The few electrons that are available for metallic bonding in aluminium metal are a probable cause for it being soft with a low melting point and low electrical resistivity. Bulk Aluminium metal has an appearance ranging from silvery white to dull gray, depending on the surface roughness. A fresh film of aluminium serves as a good reflector (approximately 92%) of visible light and an excellent reflector (as much as 98%) of medium and far infrared radiation.

All other isotopes of aluminium are radioactive. The most stable of these is 26Al: while it was present along with stable 27Al in the interstellar medium from which the Solar System formed, having been produced by stellar nucleosynthesis as well, its half-life is only 717,000 years and therefore a detectable amount has not survived since the formation of the planet. However, minute traces of 26Al are produced from argon in the atmosphere by spallation caused by cosmic ray protons. The ratio of 26Al to 10Be has been used for radiodating of geological processes over 105 to 106 year time scales, in particular transport, deposition, sediment storage, burial times, and erosion. Most meteorite scientists believe that the energy released by the decay of 26Al was responsible for the melting and differentiation of some asteroids after their formation 4.55 billion years ago. The remaining isotopes of aluminium, with mass numbers ranging from 22 to 43, all have half-lives well under an hour. Three metastable states are known, all with half-lives under a minute. Electron shell An aluminium atom has 13 electrons, arranged in an electron configuration of [Ne] 3s2 3p1, with three electrons beyond a stable noble gas configuration. Accordingly, the combined first three ionization energies of aluminium are far lower than the fourth ionization energy alone. Such an electron configuration is shared with the other well-characterized members of its group, boron, gallium, indium, and thallium; it is also expected for nihonium. Aluminium can relatively easily surrender its three outermost electrons in many chemical reactions (see below). The electronegativity of aluminium is 1.61 (Pauling scale). A free aluminium atom has a radius of 143 pm. With the three outermost electrons removed, the radius shrinks to 39 pm for a 4-coordinated atom or 53.5 pm for a 6-coordinated atom. At standard temperature and pressure, aluminium atoms (when not affected by atoms of other elements) form a face-centered cubic crystal system bound by metallic bonding provided by atoms' outermost electrons; hence aluminium (at these conditions) is a metal. This crystal system is shared by many other metals, such as lead and copper; the size of a unit cell of aluminium is comparable to that of those other metals. The system, however, is not shared by the other members of its group; boron has ionization energies too high to allow metallization, thallium has a hexagonal close-packed structure, and gallium and indium have unusual structures that are not close-packed like those of aluminium and thallium. The few electrons that are available for metallic bonding in aluminium metal are a probable cause for it being soft with a low melting point and low electrical resistivity. Bulk Aluminium metal has an appearance ranging from silvery white to dull gray, depending on the surface roughness. A fresh film of aluminium serves as a good reflector (approximately 92%) of visible light and an excellent reflector (as much as 98%) of medium and far infrared radiation.

Aluminium mirrors are the most reflective of all metal mirrors for the near ultraviolet and far infrared light, and one of the most reflective in the visible spectrum, nearly on par with silver, and the two therefore look similar. Aluminium is also good at reflecting solar radiation, although prolonged exposure to sunlight in air adds wear to the surface of the metal; this may be prevented if aluminium is anodized, which adds a protective layer of oxide on the surface. The density of aluminium is 2.70 g/cm3, about 1/3 that of steel, much lower than other commonly encountered metals, making aluminium parts easily identifiable through their lightness. Aluminium's low density compared to most other metals arises from the fact that its nuclei are much lighter, while difference in the unit cell size does not compensate for this difference. The only lighter metals are the metals of groups 1 and 2, which apart from beryllium and magnesium are too reactive for structural use (and beryllium is very toxic). Aluminium is not as strong or stiff as steel, but the low density makes up for this in the aerospace industry and for many other applications where light weight and relatively high strength are crucial. Pure aluminium is quite soft and lacking in strength. In most applications various aluminium alloys are used instead because of their higher strength and hardness. The yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium is ductile, with a percent elongation of 50-70%, and malleable allowing it to be easily drawn and extruded. It is also easily machined and cast. Aluminium is an excellent thermal and electrical conductor, having around 60% the conductivity of copper, both thermal and electrical, while having only 30% of copper's density. Aluminium is capable of superconductivity, with a superconducting critical temperature of 1.2 kelvin and a critical magnetic field of about 100 gauss (10 milliteslas). It is paramagnetic and thus essentially unaffected by static magnetic fields. The high electrical conductivity, however, means that it is strongly affected by alternating magnetic fields through the induction of eddy currents. Chemistry Aluminium combines characteristics of pre- and post-transition metals. Since it has few available electrons for metallic bonding, like its heavier group 13 congeners, it has the characteristic physical properties of a post-transition metal, with longer-than-expected interatomic distances. Furthermore, as Al3+ is a small and highly charged cation, it is strongly polarizing and bonding in aluminium compounds tends towards covalency; this behavior is similar to that of beryllium (Be2+), and the two display an example of a diagonal relationship. The underlying core under aluminium's valence shell is that of the preceding noble gas, whereas those of its heavier congeners gallium, indium, thallium, and nihonium also include a filled d-subshell and in some cases a filled f-subshell. Hence, the inner electrons of aluminium shield the valence electrons almost completely, unlike those of aluminium's heavier congeners.

Aluminium mirrors are the most reflective of all metal mirrors for the near ultraviolet and far infrared light, and one of the most reflective in the visible spectrum, nearly on par with silver, and the two therefore look similar. Aluminium is also good at reflecting solar radiation, although prolonged exposure to sunlight in air adds wear to the surface of the metal; this may be prevented if aluminium is anodized, which adds a protective layer of oxide on the surface. The density of aluminium is 2.70 g/cm3, about 1/3 that of steel, much lower than other commonly encountered metals, making aluminium parts easily identifiable through their lightness. Aluminium's low density compared to most other metals arises from the fact that its nuclei are much lighter, while difference in the unit cell size does not compensate for this difference. The only lighter metals are the metals of groups 1 and 2, which apart from beryllium and magnesium are too reactive for structural use (and beryllium is very toxic). Aluminium is not as strong or stiff as steel, but the low density makes up for this in the aerospace industry and for many other applications where light weight and relatively high strength are crucial. Pure aluminium is quite soft and lacking in strength. In most applications various aluminium alloys are used instead because of their higher strength and hardness. The yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium is ductile, with a percent elongation of 50-70%, and malleable allowing it to be easily drawn and extruded. It is also easily machined and cast. Aluminium is an excellent thermal and electrical conductor, having around 60% the conductivity of copper, both thermal and electrical, while having only 30% of copper's density. Aluminium is capable of superconductivity, with a superconducting critical temperature of 1.2 kelvin and a critical magnetic field of about 100 gauss (10 milliteslas). It is paramagnetic and thus essentially unaffected by static magnetic fields. The high electrical conductivity, however, means that it is strongly affected by alternating magnetic fields through the induction of eddy currents. Chemistry Aluminium combines characteristics of pre- and post-transition metals. Since it has few available electrons for metallic bonding, like its heavier group 13 congeners, it has the characteristic physical properties of a post-transition metal, with longer-than-expected interatomic distances. Furthermore, as Al3+ is a small and highly charged cation, it is strongly polarizing and bonding in aluminium compounds tends towards covalency; this behavior is similar to that of beryllium (Be2+), and the two display an example of a diagonal relationship. The underlying core under aluminium's valence shell is that of the preceding noble gas, whereas those of its heavier congeners gallium, indium, thallium, and nihonium also include a filled d-subshell and in some cases a filled f-subshell. Hence, the inner electrons of aluminium shield the valence electrons almost completely, unlike those of aluminium's heavier congeners.

Aluminium mirrors are the most reflective of all metal mirrors for the near ultraviolet and far infrared light, and one of the most reflective in the visible spectrum, nearly on par with silver, and the two therefore look similar. Aluminium is also good at reflecting solar radiation, although prolonged exposure to sunlight in air adds wear to the surface of the metal; this may be prevented if aluminium is anodized, which adds a protective layer of oxide on the surface. The density of aluminium is 2.70 g/cm3, about 1/3 that of steel, much lower than other commonly encountered metals, making aluminium parts easily identifiable through their lightness. Aluminium's low density compared to most other metals arises from the fact that its nuclei are much lighter, while difference in the unit cell size does not compensate for this difference. The only lighter metals are the metals of groups 1 and 2, which apart from beryllium and magnesium are too reactive for structural use (and beryllium is very toxic). Aluminium is not as strong or stiff as steel, but the low density makes up for this in the aerospace industry and for many other applications where light weight and relatively high strength are crucial. Pure aluminium is quite soft and lacking in strength. In most applications various aluminium alloys are used instead because of their higher strength and hardness. The yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium is ductile, with a percent elongation of 50-70%, and malleable allowing it to be easily drawn and extruded. It is also easily machined and cast. Aluminium is an excellent thermal and electrical conductor, having around 60% the conductivity of copper, both thermal and electrical, while having only 30% of copper's density. Aluminium is capable of superconductivity, with a superconducting critical temperature of 1.2 kelvin and a critical magnetic field of about 100 gauss (10 milliteslas). It is paramagnetic and thus essentially unaffected by static magnetic fields. The high electrical conductivity, however, means that it is strongly affected by alternating magnetic fields through the induction of eddy currents. Chemistry Aluminium combines characteristics of pre- and post-transition metals. Since it has few available electrons for metallic bonding, like its heavier group 13 congeners, it has the characteristic physical properties of a post-transition metal, with longer-than-expected interatomic distances. Furthermore, as Al3+ is a small and highly charged cation, it is strongly polarizing and bonding in aluminium compounds tends towards covalency; this behavior is similar to that of beryllium (Be2+), and the two display an example of a diagonal relationship. The underlying core under aluminium's valence shell is that of the preceding noble gas, whereas those of its heavier congeners gallium, indium, thallium, and nihonium also include a filled d-subshell and in some cases a filled f-subshell. Hence, the inner electrons of aluminium shield the valence electrons almost completely, unlike those of aluminium's heavier congeners.

As such, aluminium is the most electropositive metal in its group, and its hydroxide is in fact more basic than that of gallium. Aluminium also bears minor similarities to the metalloid boron in the same group: AlX3 compounds are valence isoelectronic to BX3 compounds (they have the same valence electronic structure), and both behave as Lewis acids and readily form adducts. Additionally, one of the main motifs of boron chemistry is regular icosahedral structures, and aluminium forms an important part of many icosahedral quasicrystal alloys, including the Al–Zn–Mg class. Aluminium has a high chemical affinity to oxygen, which renders it suitable for use as a reducing agent in the thermite reaction. A fine powder of aluminium metal reacts explosively on contact with liquid oxygen; under normal conditions, however, aluminium forms a thin oxide layer (~5 nm at room temperature) that protects the metal from further corrosion by oxygen, water, or dilute acid, a process termed passivation. Because of its general resistance to corrosion, aluminium is one of the few metals that retains silvery reflectance in finely powdered form, making it an important component of silver-colored paints. Aluminium is not attacked by oxidizing acids because of its passivation. This allows aluminium to be used to store reagents such as nitric acid, concentrated sulfuric acid, and some organic acids. In hot concentrated hydrochloric acid, aluminium reacts with water with evolution of hydrogen, and in aqueous sodium hydroxide or potassium hydroxide at room temperature to form aluminates—protective passivation under these conditions is negligible. Aqua regia also dissolves aluminium. Aluminium is corroded by dissolved chlorides, such as common sodium chloride, which is why household plumbing is never made from aluminium. The oxide layer on aluminium is also destroyed by contact with mercury due to amalgamation or with salts of some electropositive metals. As such, the strongest aluminium alloys are less corrosion-resistant due to galvanic reactions with alloyed copper, and aluminium's corrosion resistance is greatly reduced by aqueous salts, particularly in the presence of dissimilar metals. Aluminium reacts with most nonmetals upon heating, forming compounds such as aluminium nitride (AlN), aluminium sulfide (Al2S3), and the aluminium halides (AlX3). It also forms a wide range of intermetallic compounds involving metals from every group on the periodic table. Inorganic compounds The vast majority of compounds, including all aluminium-containing minerals and all commercially significant aluminium compounds, feature aluminium in the oxidation state 3+. The coordination number of such compounds varies, but generally Al3+ is either six- or four-coordinate. Almost all compounds of aluminium(III) are colorless. In aqueous solution, Al3+ exists as the hexaaqua cation [Al(H2O)6]3+, which has an approximate Ka of 10−5. Such solutions are acidic as this cation can act as a proton donor and progressively hydrolyze until a precipitate of aluminium hydroxide, Al(OH)3, forms. This is useful for clarification of water, as the precipitate nucleates on suspended particles in the water, hence removing them. Increasing the pH even further leads to the hydroxide dissolving again as aluminate, [Al(H2O)2(OH)4]−, is formed.

As such, aluminium is the most electropositive metal in its group, and its hydroxide is in fact more basic than that of gallium. Aluminium also bears minor similarities to the metalloid boron in the same group: AlX3 compounds are valence isoelectronic to BX3 compounds (they have the same valence electronic structure), and both behave as Lewis acids and readily form adducts. Additionally, one of the main motifs of boron chemistry is regular icosahedral structures, and aluminium forms an important part of many icosahedral quasicrystal alloys, including the Al–Zn–Mg class. Aluminium has a high chemical affinity to oxygen, which renders it suitable for use as a reducing agent in the thermite reaction. A fine powder of aluminium metal reacts explosively on contact with liquid oxygen; under normal conditions, however, aluminium forms a thin oxide layer (~5 nm at room temperature) that protects the metal from further corrosion by oxygen, water, or dilute acid, a process termed passivation. Because of its general resistance to corrosion, aluminium is one of the few metals that retains silvery reflectance in finely powdered form, making it an important component of silver-colored paints. Aluminium is not attacked by oxidizing acids because of its passivation. This allows aluminium to be used to store reagents such as nitric acid, concentrated sulfuric acid, and some organic acids. In hot concentrated hydrochloric acid, aluminium reacts with water with evolution of hydrogen, and in aqueous sodium hydroxide or potassium hydroxide at room temperature to form aluminates—protective passivation under these conditions is negligible. Aqua regia also dissolves aluminium. Aluminium is corroded by dissolved chlorides, such as common sodium chloride, which is why household plumbing is never made from aluminium. The oxide layer on aluminium is also destroyed by contact with mercury due to amalgamation or with salts of some electropositive metals. As such, the strongest aluminium alloys are less corrosion-resistant due to galvanic reactions with alloyed copper, and aluminium's corrosion resistance is greatly reduced by aqueous salts, particularly in the presence of dissimilar metals. Aluminium reacts with most nonmetals upon heating, forming compounds such as aluminium nitride (AlN), aluminium sulfide (Al2S3), and the aluminium halides (AlX3). It also forms a wide range of intermetallic compounds involving metals from every group on the periodic table. Inorganic compounds The vast majority of compounds, including all aluminium-containing minerals and all commercially significant aluminium compounds, feature aluminium in the oxidation state 3+. The coordination number of such compounds varies, but generally Al3+ is either six- or four-coordinate. Almost all compounds of aluminium(III) are colorless. In aqueous solution, Al3+ exists as the hexaaqua cation [Al(H2O)6]3+, which has an approximate Ka of 10−5. Such solutions are acidic as this cation can act as a proton donor and progressively hydrolyze until a precipitate of aluminium hydroxide, Al(OH)3, forms. This is useful for clarification of water, as the precipitate nucleates on suspended particles in the water, hence removing them. Increasing the pH even further leads to the hydroxide dissolving again as aluminate, [Al(H2O)2(OH)4]−, is formed.

As such, aluminium is the most electropositive metal in its group, and its hydroxide is in fact more basic than that of gallium. Aluminium also bears minor similarities to the metalloid boron in the same group: AlX3 compounds are valence isoelectronic to BX3 compounds (they have the same valence electronic structure), and both behave as Lewis acids and readily form adducts. Additionally, one of the main motifs of boron chemistry is regular icosahedral structures, and aluminium forms an important part of many icosahedral quasicrystal alloys, including the Al–Zn–Mg class. Aluminium has a high chemical affinity to oxygen, which renders it suitable for use as a reducing agent in the thermite reaction. A fine powder of aluminium metal reacts explosively on contact with liquid oxygen; under normal conditions, however, aluminium forms a thin oxide layer (~5 nm at room temperature) that protects the metal from further corrosion by oxygen, water, or dilute acid, a process termed passivation. Because of its general resistance to corrosion, aluminium is one of the few metals that retains silvery reflectance in finely powdered form, making it an important component of silver-colored paints. Aluminium is not attacked by oxidizing acids because of its passivation. This allows aluminium to be used to store reagents such as nitric acid, concentrated sulfuric acid, and some organic acids. In hot concentrated hydrochloric acid, aluminium reacts with water with evolution of hydrogen, and in aqueous sodium hydroxide or potassium hydroxide at room temperature to form aluminates—protective passivation under these conditions is negligible. Aqua regia also dissolves aluminium. Aluminium is corroded by dissolved chlorides, such as common sodium chloride, which is why household plumbing is never made from aluminium. The oxide layer on aluminium is also destroyed by contact with mercury due to amalgamation or with salts of some electropositive metals. As such, the strongest aluminium alloys are less corrosion-resistant due to galvanic reactions with alloyed copper, and aluminium's corrosion resistance is greatly reduced by aqueous salts, particularly in the presence of dissimilar metals. Aluminium reacts with most nonmetals upon heating, forming compounds such as aluminium nitride (AlN), aluminium sulfide (Al2S3), and the aluminium halides (AlX3). It also forms a wide range of intermetallic compounds involving metals from every group on the periodic table. Inorganic compounds The vast majority of compounds, including all aluminium-containing minerals and all commercially significant aluminium compounds, feature aluminium in the oxidation state 3+. The coordination number of such compounds varies, but generally Al3+ is either six- or four-coordinate. Almost all compounds of aluminium(III) are colorless. In aqueous solution, Al3+ exists as the hexaaqua cation [Al(H2O)6]3+, which has an approximate Ka of 10−5. Such solutions are acidic as this cation can act as a proton donor and progressively hydrolyze until a precipitate of aluminium hydroxide, Al(OH)3, forms. This is useful for clarification of water, as the precipitate nucleates on suspended particles in the water, hence removing them. Increasing the pH even further leads to the hydroxide dissolving again as aluminate, [Al(H2O)2(OH)4]−, is formed.

Aluminium hydroxide forms both salts and aluminates and dissolves in acid and alkali, as well as on fusion with acidic and basic oxides. This behavior of Al(OH)3 is termed amphoterism and is characteristic of weakly basic cations that form insoluble hydroxides and whose hydrated species can also donate their protons. One effect of this is that aluminium salts with weak acids are hydrolyzed in water to the aquated hydroxide and the corresponding nonmetal hydride: for example, aluminium sulfide yields hydrogen sulfide. However, some salts like aluminium carbonate exist in aqueous solution but are unstable as such; and only incomplete hydrolysis takes place for salts with strong acids, such as the halides, nitrate, and sulfate. For similar reasons, anhydrous aluminium salts cannot be made by heating their "hydrates": hydrated aluminium chloride is in fact not AlCl3·6H2O but [Al(H2O)6]Cl3, and the Al–O bonds are so strong that heating is not sufficient to break them and form Al–Cl bonds instead: 2[Al(H2O)6]Cl3 Al2O3 + 6 HCl + 9 H2O All four trihalides are well known. Unlike the structures of the three heavier trihalides, aluminium fluoride (AlF3) features six-coordinate aluminium, which explains its involatility and insolubility as well as high heat of formation. Each aluminium atom is surrounded by six fluorine atoms in a distorted octahedral arrangement, with each fluorine atom being shared between the corners of two octahedra. Such {AlF6} units also exist in complex fluorides such as cryolite, Na3AlF6. AlF3 melts at and is made by reaction of aluminium oxide with hydrogen fluoride gas at . With heavier halides, the coordination numbers are lower. The other trihalides are dimeric or polymeric with tetrahedral four-coordinate aluminium centers. Aluminium trichloride (AlCl3) has a layered polymeric structure below its melting point of but transforms on melting to Al2Cl6 dimers. At higher temperatures those increasingly dissociate into trigonal planar AlCl3 monomers similar to the structure of BCl3. Aluminium tribromide and aluminium triiodide form Al2X6 dimers in all three phases and hence do not show such significant changes of properties upon phase change. These materials are prepared by treating aluminium metal with the halogen. The aluminium trihalides form many addition compounds or complexes; their Lewis acidic nature makes them useful as catalysts for the Friedel–Crafts reactions. Aluminium trichloride has major industrial uses involving this reaction, such as in the manufacture of anthraquinones and styrene; it is also often used as the precursor for many other aluminium compounds and as a reagent for converting nonmetal fluorides into the corresponding chlorides (a transhalogenation reaction). Aluminium forms one stable oxide with the chemical formula Al2O3, commonly called alumina. It can be found in nature in the mineral corundum, α-alumina; there is also a γ-alumina phase.

Aluminium hydroxide forms both salts and aluminates and dissolves in acid and alkali, as well as on fusion with acidic and basic oxides. This behavior of Al(OH)3 is termed amphoterism and is characteristic of weakly basic cations that form insoluble hydroxides and whose hydrated species can also donate their protons. One effect of this is that aluminium salts with weak acids are hydrolyzed in water to the aquated hydroxide and the corresponding nonmetal hydride: for example, aluminium sulfide yields hydrogen sulfide. However, some salts like aluminium carbonate exist in aqueous solution but are unstable as such; and only incomplete hydrolysis takes place for salts with strong acids, such as the halides, nitrate, and sulfate. For similar reasons, anhydrous aluminium salts cannot be made by heating their "hydrates": hydrated aluminium chloride is in fact not AlCl3·6H2O but [Al(H2O)6]Cl3, and the Al–O bonds are so strong that heating is not sufficient to break them and form Al–Cl bonds instead: 2[Al(H2O)6]Cl3 Al2O3 + 6 HCl + 9 H2O All four trihalides are well known. Unlike the structures of the three heavier trihalides, aluminium fluoride (AlF3) features six-coordinate aluminium, which explains its involatility and insolubility as well as high heat of formation. Each aluminium atom is surrounded by six fluorine atoms in a distorted octahedral arrangement, with each fluorine atom being shared between the corners of two octahedra. Such {AlF6} units also exist in complex fluorides such as cryolite, Na3AlF6. AlF3 melts at and is made by reaction of aluminium oxide with hydrogen fluoride gas at . With heavier halides, the coordination numbers are lower. The other trihalides are dimeric or polymeric with tetrahedral four-coordinate aluminium centers. Aluminium trichloride (AlCl3) has a layered polymeric structure below its melting point of but transforms on melting to Al2Cl6 dimers. At higher temperatures those increasingly dissociate into trigonal planar AlCl3 monomers similar to the structure of BCl3. Aluminium tribromide and aluminium triiodide form Al2X6 dimers in all three phases and hence do not show such significant changes of properties upon phase change. These materials are prepared by treating aluminium metal with the halogen. The aluminium trihalides form many addition compounds or complexes; their Lewis acidic nature makes them useful as catalysts for the Friedel–Crafts reactions. Aluminium trichloride has major industrial uses involving this reaction, such as in the manufacture of anthraquinones and styrene; it is also often used as the precursor for many other aluminium compounds and as a reagent for converting nonmetal fluorides into the corresponding chlorides (a transhalogenation reaction). Aluminium forms one stable oxide with the chemical formula Al2O3, commonly called alumina. It can be found in nature in the mineral corundum, α-alumina; there is also a γ-alumina phase.

Aluminium hydroxide forms both salts and aluminates and dissolves in acid and alkali, as well as on fusion with acidic and basic oxides. This behavior of Al(OH)3 is termed amphoterism and is characteristic of weakly basic cations that form insoluble hydroxides and whose hydrated species can also donate their protons. One effect of this is that aluminium salts with weak acids are hydrolyzed in water to the aquated hydroxide and the corresponding nonmetal hydride: for example, aluminium sulfide yields hydrogen sulfide. However, some salts like aluminium carbonate exist in aqueous solution but are unstable as such; and only incomplete hydrolysis takes place for salts with strong acids, such as the halides, nitrate, and sulfate. For similar reasons, anhydrous aluminium salts cannot be made by heating their "hydrates": hydrated aluminium chloride is in fact not AlCl3·6H2O but [Al(H2O)6]Cl3, and the Al–O bonds are so strong that heating is not sufficient to break them and form Al–Cl bonds instead: 2[Al(H2O)6]Cl3 Al2O3 + 6 HCl + 9 H2O All four trihalides are well known. Unlike the structures of the three heavier trihalides, aluminium fluoride (AlF3) features six-coordinate aluminium, which explains its involatility and insolubility as well as high heat of formation. Each aluminium atom is surrounded by six fluorine atoms in a distorted octahedral arrangement, with each fluorine atom being shared between the corners of two octahedra. Such {AlF6} units also exist in complex fluorides such as cryolite, Na3AlF6. AlF3 melts at and is made by reaction of aluminium oxide with hydrogen fluoride gas at . With heavier halides, the coordination numbers are lower. The other trihalides are dimeric or polymeric with tetrahedral four-coordinate aluminium centers. Aluminium trichloride (AlCl3) has a layered polymeric structure below its melting point of but transforms on melting to Al2Cl6 dimers. At higher temperatures those increasingly dissociate into trigonal planar AlCl3 monomers similar to the structure of BCl3. Aluminium tribromide and aluminium triiodide form Al2X6 dimers in all three phases and hence do not show such significant changes of properties upon phase change. These materials are prepared by treating aluminium metal with the halogen. The aluminium trihalides form many addition compounds or complexes; their Lewis acidic nature makes them useful as catalysts for the Friedel–Crafts reactions. Aluminium trichloride has major industrial uses involving this reaction, such as in the manufacture of anthraquinones and styrene; it is also often used as the precursor for many other aluminium compounds and as a reagent for converting nonmetal fluorides into the corresponding chlorides (a transhalogenation reaction). Aluminium forms one stable oxide with the chemical formula Al2O3, commonly called alumina. It can be found in nature in the mineral corundum, α-alumina; there is also a γ-alumina phase.

Its crystalline form, corundum, is very hard (Mohs hardness 9), has a high melting point of , has very low volatility, is chemically inert, and a good electrical insulator, it is often used in abrasives (such as toothpaste), as a refractory material, and in ceramics, as well as being the starting material for the electrolytic production of aluminium metal. Sapphire and ruby are impure corundum contaminated with trace amounts of other metals. The two main oxide-hydroxides, AlO(OH), are boehmite and diaspore. There are three main trihydroxides: bayerite, gibbsite, and nordstrandite, which differ in their crystalline structure (polymorphs). Many other intermediate and related structures are also known. Most are produced from ores by a variety of wet processes using acid and base. Heating the hydroxides leads to formation of corundum. These materials are of central importance to the production of aluminium and are themselves extremely useful. Some mixed oxide phases are also very useful, such as spinel (MgAl2O4), Na-β-alumina (NaAl11O17), and tricalcium aluminate (Ca3Al2O6, an important mineral phase in Portland cement). The only stable chalcogenides under normal conditions are aluminium sulfide (Al2S3), selenide (Al2Se3), and telluride (Al2Te3). All three are prepared by direct reaction of their elements at about and quickly hydrolyze completely in water to yield aluminium hydroxide and the respective hydrogen chalcogenide. As aluminium is a small atom relative to these chalcogens, these have four-coordinate tetrahedral aluminium with various polymorphs having structures related to wurtzite, with two-thirds of the possible metal sites occupied either in an orderly (α) or random (β) fashion; the sulfide also has a γ form related to γ-alumina, and an unusual high-temperature hexagonal form where half the aluminium atoms have tetrahedral four-coordination and the other half have trigonal bipyramidal five-coordination. Four pnictides – aluminium nitride (AlN), aluminium phosphide (AlP), aluminium arsenide (AlAs), and aluminium antimonide (AlSb) – are known. They are all III-V semiconductors isoelectronic to silicon and germanium, all of which but AlN have the zinc blende structure. All four can be made by high-temperature (and possibly high-pressure) direct reaction of their component elements. Aluminium alloys well with most other metals (with the exception of most alkali metals and group 13 metals) and over 150 intermetallics with other metals are known. Preparation involves heating fixed metals together in certain proportion, followed by gradual cooling and annealing. Bonding in them is predominantly metallic and the crystal structure primarily depends on efficiency of packing. There are few compounds with lower oxidation states. A few aluminium(I) compounds exist: AlF, AlCl, AlBr, and AlI exist in the gaseous phase when the respective trihalide is heated with aluminium, and at cryogenic temperatures. A stable derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine, Al4I4(NEt3)4. Al2O and Al2S also exist but are very unstable. Very simple aluminium(II) compounds are invoked or observed in the reactions of Al metal with oxidants. For example, aluminium monoxide, AlO, has been detected in the gas phase after explosion and in stellar absorption spectra.

Its crystalline form, corundum, is very hard (Mohs hardness 9), has a high melting point of , has very low volatility, is chemically inert, and a good electrical insulator, it is often used in abrasives (such as toothpaste), as a refractory material, and in ceramics, as well as being the starting material for the electrolytic production of aluminium metal. Sapphire and ruby are impure corundum contaminated with trace amounts of other metals. The two main oxide-hydroxides, AlO(OH), are boehmite and diaspore. There are three main trihydroxides: bayerite, gibbsite, and nordstrandite, which differ in their crystalline structure (polymorphs). Many other intermediate and related structures are also known. Most are produced from ores by a variety of wet processes using acid and base. Heating the hydroxides leads to formation of corundum. These materials are of central importance to the production of aluminium and are themselves extremely useful. Some mixed oxide phases are also very useful, such as spinel (MgAl2O4), Na-β-alumina (NaAl11O17), and tricalcium aluminate (Ca3Al2O6, an important mineral phase in Portland cement). The only stable chalcogenides under normal conditions are aluminium sulfide (Al2S3), selenide (Al2Se3), and telluride (Al2Te3). All three are prepared by direct reaction of their elements at about and quickly hydrolyze completely in water to yield aluminium hydroxide and the respective hydrogen chalcogenide. As aluminium is a small atom relative to these chalcogens, these have four-coordinate tetrahedral aluminium with various polymorphs having structures related to wurtzite, with two-thirds of the possible metal sites occupied either in an orderly (α) or random (β) fashion; the sulfide also has a γ form related to γ-alumina, and an unusual high-temperature hexagonal form where half the aluminium atoms have tetrahedral four-coordination and the other half have trigonal bipyramidal five-coordination. Four pnictides – aluminium nitride (AlN), aluminium phosphide (AlP), aluminium arsenide (AlAs), and aluminium antimonide (AlSb) – are known. They are all III-V semiconductors isoelectronic to silicon and germanium, all of which but AlN have the zinc blende structure. All four can be made by high-temperature (and possibly high-pressure) direct reaction of their component elements. Aluminium alloys well with most other metals (with the exception of most alkali metals and group 13 metals) and over 150 intermetallics with other metals are known. Preparation involves heating fixed metals together in certain proportion, followed by gradual cooling and annealing. Bonding in them is predominantly metallic and the crystal structure primarily depends on efficiency of packing. There are few compounds with lower oxidation states. A few aluminium(I) compounds exist: AlF, AlCl, AlBr, and AlI exist in the gaseous phase when the respective trihalide is heated with aluminium, and at cryogenic temperatures. A stable derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine, Al4I4(NEt3)4. Al2O and Al2S also exist but are very unstable. Very simple aluminium(II) compounds are invoked or observed in the reactions of Al metal with oxidants. For example, aluminium monoxide, AlO, has been detected in the gas phase after explosion and in stellar absorption spectra.

Its crystalline form, corundum, is very hard (Mohs hardness 9), has a high melting point of , has very low volatility, is chemically inert, and a good electrical insulator, it is often used in abrasives (such as toothpaste), as a refractory material, and in ceramics, as well as being the starting material for the electrolytic production of aluminium metal. Sapphire and ruby are impure corundum contaminated with trace amounts of other metals. The two main oxide-hydroxides, AlO(OH), are boehmite and diaspore. There are three main trihydroxides: bayerite, gibbsite, and nordstrandite, which differ in their crystalline structure (polymorphs). Many other intermediate and related structures are also known. Most are produced from ores by a variety of wet processes using acid and base. Heating the hydroxides leads to formation of corundum. These materials are of central importance to the production of aluminium and are themselves extremely useful. Some mixed oxide phases are also very useful, such as spinel (MgAl2O4), Na-β-alumina (NaAl11O17), and tricalcium aluminate (Ca3Al2O6, an important mineral phase in Portland cement). The only stable chalcogenides under normal conditions are aluminium sulfide (Al2S3), selenide (Al2Se3), and telluride (Al2Te3). All three are prepared by direct reaction of their elements at about and quickly hydrolyze completely in water to yield aluminium hydroxide and the respective hydrogen chalcogenide. As aluminium is a small atom relative to these chalcogens, these have four-coordinate tetrahedral aluminium with various polymorphs having structures related to wurtzite, with two-thirds of the possible metal sites occupied either in an orderly (α) or random (β) fashion; the sulfide also has a γ form related to γ-alumina, and an unusual high-temperature hexagonal form where half the aluminium atoms have tetrahedral four-coordination and the other half have trigonal bipyramidal five-coordination. Four pnictides – aluminium nitride (AlN), aluminium phosphide (AlP), aluminium arsenide (AlAs), and aluminium antimonide (AlSb) – are known. They are all III-V semiconductors isoelectronic to silicon and germanium, all of which but AlN have the zinc blende structure. All four can be made by high-temperature (and possibly high-pressure) direct reaction of their component elements. Aluminium alloys well with most other metals (with the exception of most alkali metals and group 13 metals) and over 150 intermetallics with other metals are known. Preparation involves heating fixed metals together in certain proportion, followed by gradual cooling and annealing. Bonding in them is predominantly metallic and the crystal structure primarily depends on efficiency of packing. There are few compounds with lower oxidation states. A few aluminium(I) compounds exist: AlF, AlCl, AlBr, and AlI exist in the gaseous phase when the respective trihalide is heated with aluminium, and at cryogenic temperatures. A stable derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine, Al4I4(NEt3)4. Al2O and Al2S also exist but are very unstable. Very simple aluminium(II) compounds are invoked or observed in the reactions of Al metal with oxidants. For example, aluminium monoxide, AlO, has been detected in the gas phase after explosion and in stellar absorption spectra.

More thoroughly investigated are compounds of the formula R4Al2 which contain an Al–Al bond and where R is a large organic ligand. Organoaluminium compounds and related hydrides A variety of compounds of empirical formula AlR3 and AlR1.5Cl1.5 exist. The aluminium trialkyls and triaryls are reactive, volatile, and colorless liquids or low-melting solids. They catch fire spontaneously in air and react with water, thus necessitating precautions when handling them. They often form dimers, unlike their boron analogues, but this tendency diminishes for branched-chain alkyls (e.g. Pri, Bui, Me3CCH2); for example, triisobutylaluminium exists as an equilibrium mixture of the monomer and dimer. These dimers, such as trimethylaluminium (Al2Me6), usually feature tetrahedral Al centers formed by dimerization with some alkyl group bridging between both aluminium atoms. They are hard acids and react readily with ligands, forming adducts. In industry, they are mostly used in alkene insertion reactions, as discovered by Karl Ziegler, most importantly in "growth reactions" that form long-chain unbranched primary alkenes and alcohols, and in the low-pressure polymerization of ethene and propene. There are also some heterocyclic and cluster organoaluminium compounds involving Al–N bonds. The industrially most important aluminium hydride is lithium aluminium hydride (LiAlH4), which is used in as a reducing agent in organic chemistry. It can be produced from lithium hydride and aluminium trichloride. The simplest hydride, aluminium hydride or alane, is not as important. It is a polymer with the formula (AlH3)n, in contrast to the corresponding boron hydride that is a dimer with the formula (BH3)2. Natural occurrence Space Aluminium's per-particle abundance in the Solar System is 3.15 ppm (parts per million). It is the twelfth most abundant of all elements and third most abundant among the elements that have odd atomic numbers, after hydrogen and nitrogen. The only stable isotope of aluminium, 27Al, is the eighteenth most abundant nucleus in the Universe. It is created almost entirely after fusion of carbon in massive stars that will later become Type II supernovas: this fusion creates 26Mg, which, upon capturing free protons and neutrons becomes aluminium. Some smaller quantities of 27Al are created in hydrogen burning shells of evolved stars, where 26Mg can capture free protons. Essentially all aluminium now in existence is 27Al. 26Al was present in the early Solar System with abundance of 0.005% relative to 27Al but its half-life of 728,000 years is too short for any original nuclei to survive; 26Al is therefore extinct. Unlike for 27Al, hydrogen burning is the primary source of 26Al, with the nuclide emerging after a nucleus of 25Mg catches a free proton. However, the trace quantities of 26Al that do exist are the most common gamma ray emitter in the interstellar gas; if the original 26Al were still present, gamma ray maps of the Milky Way would be brighter. Earth Overall, the Earth is about 1.59% aluminium by mass (seventh in abundance by mass).

More thoroughly investigated are compounds of the formula R4Al2 which contain an Al–Al bond and where R is a large organic ligand. Organoaluminium compounds and related hydrides A variety of compounds of empirical formula AlR3 and AlR1.5Cl1.5 exist. The aluminium trialkyls and triaryls are reactive, volatile, and colorless liquids or low-melting solids. They catch fire spontaneously in air and react with water, thus necessitating precautions when handling them. They often form dimers, unlike their boron analogues, but this tendency diminishes for branched-chain alkyls (e.g. Pri, Bui, Me3CCH2); for example, triisobutylaluminium exists as an equilibrium mixture of the monomer and dimer. These dimers, such as trimethylaluminium (Al2Me6), usually feature tetrahedral Al centers formed by dimerization with some alkyl group bridging between both aluminium atoms. They are hard acids and react readily with ligands, forming adducts. In industry, they are mostly used in alkene insertion reactions, as discovered by Karl Ziegler, most importantly in "growth reactions" that form long-chain unbranched primary alkenes and alcohols, and in the low-pressure polymerization of ethene and propene. There are also some heterocyclic and cluster organoaluminium compounds involving Al–N bonds. The industrially most important aluminium hydride is lithium aluminium hydride (LiAlH4), which is used in as a reducing agent in organic chemistry. It can be produced from lithium hydride and aluminium trichloride. The simplest hydride, aluminium hydride or alane, is not as important. It is a polymer with the formula (AlH3)n, in contrast to the corresponding boron hydride that is a dimer with the formula (BH3)2. Natural occurrence Space Aluminium's per-particle abundance in the Solar System is 3.15 ppm (parts per million). It is the twelfth most abundant of all elements and third most abundant among the elements that have odd atomic numbers, after hydrogen and nitrogen. The only stable isotope of aluminium, 27Al, is the eighteenth most abundant nucleus in the Universe. It is created almost entirely after fusion of carbon in massive stars that will later become Type II supernovas: this fusion creates 26Mg, which, upon capturing free protons and neutrons becomes aluminium. Some smaller quantities of 27Al are created in hydrogen burning shells of evolved stars, where 26Mg can capture free protons. Essentially all aluminium now in existence is 27Al. 26Al was present in the early Solar System with abundance of 0.005% relative to 27Al but its half-life of 728,000 years is too short for any original nuclei to survive; 26Al is therefore extinct. Unlike for 27Al, hydrogen burning is the primary source of 26Al, with the nuclide emerging after a nucleus of 25Mg catches a free proton. However, the trace quantities of 26Al that do exist are the most common gamma ray emitter in the interstellar gas; if the original 26Al were still present, gamma ray maps of the Milky Way would be brighter. Earth Overall, the Earth is about 1.59% aluminium by mass (seventh in abundance by mass).

More thoroughly investigated are compounds of the formula R4Al2 which contain an Al–Al bond and where R is a large organic ligand. Organoaluminium compounds and related hydrides A variety of compounds of empirical formula AlR3 and AlR1.5Cl1.5 exist. The aluminium trialkyls and triaryls are reactive, volatile, and colorless liquids or low-melting solids. They catch fire spontaneously in air and react with water, thus necessitating precautions when handling them. They often form dimers, unlike their boron analogues, but this tendency diminishes for branched-chain alkyls (e.g. Pri, Bui, Me3CCH2); for example, triisobutylaluminium exists as an equilibrium mixture of the monomer and dimer. These dimers, such as trimethylaluminium (Al2Me6), usually feature tetrahedral Al centers formed by dimerization with some alkyl group bridging between both aluminium atoms. They are hard acids and react readily with ligands, forming adducts. In industry, they are mostly used in alkene insertion reactions, as discovered by Karl Ziegler, most importantly in "growth reactions" that form long-chain unbranched primary alkenes and alcohols, and in the low-pressure polymerization of ethene and propene. There are also some heterocyclic and cluster organoaluminium compounds involving Al–N bonds. The industrially most important aluminium hydride is lithium aluminium hydride (LiAlH4), which is used in as a reducing agent in organic chemistry. It can be produced from lithium hydride and aluminium trichloride. The simplest hydride, aluminium hydride or alane, is not as important. It is a polymer with the formula (AlH3)n, in contrast to the corresponding boron hydride that is a dimer with the formula (BH3)2. Natural occurrence Space Aluminium's per-particle abundance in the Solar System is 3.15 ppm (parts per million). It is the twelfth most abundant of all elements and third most abundant among the elements that have odd atomic numbers, after hydrogen and nitrogen. The only stable isotope of aluminium, 27Al, is the eighteenth most abundant nucleus in the Universe. It is created almost entirely after fusion of carbon in massive stars that will later become Type II supernovas: this fusion creates 26Mg, which, upon capturing free protons and neutrons becomes aluminium. Some smaller quantities of 27Al are created in hydrogen burning shells of evolved stars, where 26Mg can capture free protons. Essentially all aluminium now in existence is 27Al. 26Al was present in the early Solar System with abundance of 0.005% relative to 27Al but its half-life of 728,000 years is too short for any original nuclei to survive; 26Al is therefore extinct. Unlike for 27Al, hydrogen burning is the primary source of 26Al, with the nuclide emerging after a nucleus of 25Mg catches a free proton. However, the trace quantities of 26Al that do exist are the most common gamma ray emitter in the interstellar gas; if the original 26Al were still present, gamma ray maps of the Milky Way would be brighter. Earth Overall, the Earth is about 1.59% aluminium by mass (seventh in abundance by mass).

Aluminium occurs in greater proportion in the Earth's crust than in the Universe at large, because aluminium easily forms the oxide and becomes bound into rocks and stays in the Earth's crust, while less reactive metals sink to the core. In the Earth's crust, aluminium is the most abundant metallic element (8.23% by mass) and the third most abundant of all elements (after oxygen and silicon). A large number of silicates in the Earth's crust contain aluminium. In contrast, the Earth's mantle is only 2.38% aluminium by mass. Aluminium also occurs in seawater at a concentration of 2 μg/kg. Because of its strong affinity for oxygen, aluminium is almost never found in the elemental state; instead it is found in oxides or silicates. Feldspars, the most common group of minerals in the Earth's crust, are aluminosilicates. Aluminium also occurs in the minerals beryl, cryolite, garnet, spinel, and turquoise. Impurities in Al2O3, such as chromium and iron, yield the gemstones ruby and sapphire, respectively. Native aluminium metal is extremely rare and can only be found as a minor phase in low oxygen fugacity environments, such as the interiors of certain volcanoes. Native aluminium has been reported in cold seeps in the northeastern continental slope of the South China Sea. It is possible that these deposits resulted from bacterial reduction of tetrahydroxoaluminate Al(OH)4−. Although aluminium is a common and widespread element, not all aluminium minerals are economically viable sources of the metal. Almost all metallic aluminium is produced from the ore bauxite (AlOx(OH)3–2x). Bauxite occurs as a weathering product of low iron and silica bedrock in tropical climatic conditions. In 2017, most bauxite was mined in Australia, China, Guinea, and India. History The history of aluminium has been shaped by usage of alum. The first written record of alum, made by Greek historian Herodotus, dates back to the 5th century BCE. The ancients are known to have used alum as a dyeing mordant and for city defense. After the Crusades, alum, an indispensable good in the European fabric industry, was a subject of international commerce; it was imported to Europe from the eastern Mediterranean until the mid-15th century. The nature of alum remained unknown. Around 1530, Swiss physician Paracelsus suggested alum was a salt of an earth of alum. In 1595, German doctor and chemist Andreas Libavius experimentally confirmed this. In 1722, German chemist Friedrich Hoffmann announced his belief that the base of alum was a distinct earth. In 1754, German chemist Andreas Sigismund Marggraf synthesized alumina by boiling clay in sulfuric acid and subsequently adding potash. Attempts to produce aluminium metal date back to 1760. The first successful attempt, however, was completed in 1824 by Danish physicist and chemist Hans Christian Ørsted. He reacted anhydrous aluminium chloride with potassium amalgam, yielding a lump of metal looking similar to tin. He presented his results and demonstrated a sample of the new metal in 1825. In 1827, German chemist Friedrich Wöhler repeated Ørsted's experiments but did not identify any aluminium.

Aluminium occurs in greater proportion in the Earth's crust than in the Universe at large, because aluminium easily forms the oxide and becomes bound into rocks and stays in the Earth's crust, while less reactive metals sink to the core. In the Earth's crust, aluminium is the most abundant metallic element (8.23% by mass) and the third most abundant of all elements (after oxygen and silicon). A large number of silicates in the Earth's crust contain aluminium. In contrast, the Earth's mantle is only 2.38% aluminium by mass. Aluminium also occurs in seawater at a concentration of 2 μg/kg. Because of its strong affinity for oxygen, aluminium is almost never found in the elemental state; instead it is found in oxides or silicates. Feldspars, the most common group of minerals in the Earth's crust, are aluminosilicates. Aluminium also occurs in the minerals beryl, cryolite, garnet, spinel, and turquoise. Impurities in Al2O3, such as chromium and iron, yield the gemstones ruby and sapphire, respectively. Native aluminium metal is extremely rare and can only be found as a minor phase in low oxygen fugacity environments, such as the interiors of certain volcanoes. Native aluminium has been reported in cold seeps in the northeastern continental slope of the South China Sea. It is possible that these deposits resulted from bacterial reduction of tetrahydroxoaluminate Al(OH)4−. Although aluminium is a common and widespread element, not all aluminium minerals are economically viable sources of the metal. Almost all metallic aluminium is produced from the ore bauxite (AlOx(OH)3–2x). Bauxite occurs as a weathering product of low iron and silica bedrock in tropical climatic conditions. In 2017, most bauxite was mined in Australia, China, Guinea, and India. History The history of aluminium has been shaped by usage of alum. The first written record of alum, made by Greek historian Herodotus, dates back to the 5th century BCE. The ancients are known to have used alum as a dyeing mordant and for city defense. After the Crusades, alum, an indispensable good in the European fabric industry, was a subject of international commerce; it was imported to Europe from the eastern Mediterranean until the mid-15th century. The nature of alum remained unknown. Around 1530, Swiss physician Paracelsus suggested alum was a salt of an earth of alum. In 1595, German doctor and chemist Andreas Libavius experimentally confirmed this. In 1722, German chemist Friedrich Hoffmann announced his belief that the base of alum was a distinct earth. In 1754, German chemist Andreas Sigismund Marggraf synthesized alumina by boiling clay in sulfuric acid and subsequently adding potash. Attempts to produce aluminium metal date back to 1760. The first successful attempt, however, was completed in 1824 by Danish physicist and chemist Hans Christian Ørsted. He reacted anhydrous aluminium chloride with potassium amalgam, yielding a lump of metal looking similar to tin. He presented his results and demonstrated a sample of the new metal in 1825. In 1827, German chemist Friedrich Wöhler repeated Ørsted's experiments but did not identify any aluminium.

Aluminium occurs in greater proportion in the Earth's crust than in the Universe at large, because aluminium easily forms the oxide and becomes bound into rocks and stays in the Earth's crust, while less reactive metals sink to the core. In the Earth's crust, aluminium is the most abundant metallic element (8.23% by mass) and the third most abundant of all elements (after oxygen and silicon). A large number of silicates in the Earth's crust contain aluminium. In contrast, the Earth's mantle is only 2.38% aluminium by mass. Aluminium also occurs in seawater at a concentration of 2 μg/kg. Because of its strong affinity for oxygen, aluminium is almost never found in the elemental state; instead it is found in oxides or silicates. Feldspars, the most common group of minerals in the Earth's crust, are aluminosilicates. Aluminium also occurs in the minerals beryl, cryolite, garnet, spinel, and turquoise. Impurities in Al2O3, such as chromium and iron, yield the gemstones ruby and sapphire, respectively. Native aluminium metal is extremely rare and can only be found as a minor phase in low oxygen fugacity environments, such as the interiors of certain volcanoes. Native aluminium has been reported in cold seeps in the northeastern continental slope of the South China Sea. It is possible that these deposits resulted from bacterial reduction of tetrahydroxoaluminate Al(OH)4−. Although aluminium is a common and widespread element, not all aluminium minerals are economically viable sources of the metal. Almost all metallic aluminium is produced from the ore bauxite (AlOx(OH)3–2x). Bauxite occurs as a weathering product of low iron and silica bedrock in tropical climatic conditions. In 2017, most bauxite was mined in Australia, China, Guinea, and India. History The history of aluminium has been shaped by usage of alum. The first written record of alum, made by Greek historian Herodotus, dates back to the 5th century BCE. The ancients are known to have used alum as a dyeing mordant and for city defense. After the Crusades, alum, an indispensable good in the European fabric industry, was a subject of international commerce; it was imported to Europe from the eastern Mediterranean until the mid-15th century. The nature of alum remained unknown. Around 1530, Swiss physician Paracelsus suggested alum was a salt of an earth of alum. In 1595, German doctor and chemist Andreas Libavius experimentally confirmed this. In 1722, German chemist Friedrich Hoffmann announced his belief that the base of alum was a distinct earth. In 1754, German chemist Andreas Sigismund Marggraf synthesized alumina by boiling clay in sulfuric acid and subsequently adding potash. Attempts to produce aluminium metal date back to 1760. The first successful attempt, however, was completed in 1824 by Danish physicist and chemist Hans Christian Ørsted. He reacted anhydrous aluminium chloride with potassium amalgam, yielding a lump of metal looking similar to tin. He presented his results and demonstrated a sample of the new metal in 1825. In 1827, German chemist Friedrich Wöhler repeated Ørsted's experiments but did not identify any aluminium.

(The reason for this inconsistency was only discovered in 1921.) He conducted a similar experiment in the same year by mixing anhydrous aluminium chloride with potassium and produced a powder of aluminium. In 1845, he was able to produce small pieces of the metal and described some physical properties of this metal. For many years thereafter, Wöhler was credited as the discoverer of aluminium. As Wöhler's method could not yield great quantities of aluminium, the metal remained rare; its cost exceeded that of gold. The first industrial production of aluminium was established in 1856 by French chemist Henri Etienne Sainte-Claire Deville and companions. Deville had discovered that aluminium trichloride could be reduced by sodium, which was more convenient and less expensive than potassium, which Wöhler had used. Even then, aluminium was still not of great purity and produced aluminium differed in properties by sample. The first industrial large-scale production method was independently developed in 1886 by French engineer Paul Héroult and American engineer Charles Martin Hall; it is now known as the Hall–Héroult process. The Hall–Héroult process converts alumina into metal. Austrian chemist Carl Joseph Bayer discovered a way of purifying bauxite to yield alumina, now known as the Bayer process, in 1889. Modern production of the aluminium metal is based on the Bayer and Hall–Héroult processes. Prices of aluminium dropped and aluminium became widely used in jewelry, everyday items, eyeglass frames, optical instruments, tableware, and foil in the 1890s and early 20th century. Aluminium's ability to form hard yet light alloys with other metals provided the metal with many uses at the time. During World War I, major governments demanded large shipments of aluminium for light strong airframes; during World War II, demand by major governments for aviation was even higher. By the mid-20th century, aluminium had become a part of everyday life and an essential component of housewares. In 1954, production of aluminium surpassed that of copper, historically second in production only to iron, making it the most produced non-ferrous metal. During the mid-20th century, aluminium emerged as a civil engineering material, with building applications in both basic construction and interior finish work, and increasingly being used in military engineering, for both airplanes and land armor vehicle engines. Earth's first artificial satellite, launched in 1957, consisted of two separate aluminium semi-spheres joined and all subsequent space vehicles have used aluminium to some extent. The aluminium can was invented in 1956 and employed as a storage for drinks in 1958. Throughout the 20th century, the production of aluminium rose rapidly: while the world production of aluminium in 1900 was 6,800 metric tons, the annual production first exceeded 100,000 metric tons in 1916; 1,000,000 tons in 1941; 10,000,000 tons in 1971. In the 1970s, the increased demand for aluminium made it an exchange commodity; it entered the London Metal Exchange, the oldest industrial metal exchange in the world, in 1978. The output continued to grow: the annual production of aluminium exceeded 50,000,000 metric tons in 2013.

(The reason for this inconsistency was only discovered in 1921.) He conducted a similar experiment in the same year by mixing anhydrous aluminium chloride with potassium and produced a powder of aluminium. In 1845, he was able to produce small pieces of the metal and described some physical properties of this metal. For many years thereafter, Wöhler was credited as the discoverer of aluminium. As Wöhler's method could not yield great quantities of aluminium, the metal remained rare; its cost exceeded that of gold. The first industrial production of aluminium was established in 1856 by French chemist Henri Etienne Sainte-Claire Deville and companions. Deville had discovered that aluminium trichloride could be reduced by sodium, which was more convenient and less expensive than potassium, which Wöhler had used. Even then, aluminium was still not of great purity and produced aluminium differed in properties by sample. The first industrial large-scale production method was independently developed in 1886 by French engineer Paul Héroult and American engineer Charles Martin Hall; it is now known as the Hall–Héroult process. The Hall–Héroult process converts alumina into metal. Austrian chemist Carl Joseph Bayer discovered a way of purifying bauxite to yield alumina, now known as the Bayer process, in 1889. Modern production of the aluminium metal is based on the Bayer and Hall–Héroult processes. Prices of aluminium dropped and aluminium became widely used in jewelry, everyday items, eyeglass frames, optical instruments, tableware, and foil in the 1890s and early 20th century. Aluminium's ability to form hard yet light alloys with other metals provided the metal with many uses at the time. During World War I, major governments demanded large shipments of aluminium for light strong airframes; during World War II, demand by major governments for aviation was even higher. By the mid-20th century, aluminium had become a part of everyday life and an essential component of housewares. In 1954, production of aluminium surpassed that of copper, historically second in production only to iron, making it the most produced non-ferrous metal. During the mid-20th century, aluminium emerged as a civil engineering material, with building applications in both basic construction and interior finish work, and increasingly being used in military engineering, for both airplanes and land armor vehicle engines. Earth's first artificial satellite, launched in 1957, consisted of two separate aluminium semi-spheres joined and all subsequent space vehicles have used aluminium to some extent. The aluminium can was invented in 1956 and employed as a storage for drinks in 1958. Throughout the 20th century, the production of aluminium rose rapidly: while the world production of aluminium in 1900 was 6,800 metric tons, the annual production first exceeded 100,000 metric tons in 1916; 1,000,000 tons in 1941; 10,000,000 tons in 1971. In the 1970s, the increased demand for aluminium made it an exchange commodity; it entered the London Metal Exchange, the oldest industrial metal exchange in the world, in 1978. The output continued to grow: the annual production of aluminium exceeded 50,000,000 metric tons in 2013.

(The reason for this inconsistency was only discovered in 1921.) He conducted a similar experiment in the same year by mixing anhydrous aluminium chloride with potassium and produced a powder of aluminium. In 1845, he was able to produce small pieces of the metal and described some physical properties of this metal. For many years thereafter, Wöhler was credited as the discoverer of aluminium. As Wöhler's method could not yield great quantities of aluminium, the metal remained rare; its cost exceeded that of gold. The first industrial production of aluminium was established in 1856 by French chemist Henri Etienne Sainte-Claire Deville and companions. Deville had discovered that aluminium trichloride could be reduced by sodium, which was more convenient and less expensive than potassium, which Wöhler had used. Even then, aluminium was still not of great purity and produced aluminium differed in properties by sample. The first industrial large-scale production method was independently developed in 1886 by French engineer Paul Héroult and American engineer Charles Martin Hall; it is now known as the Hall–Héroult process. The Hall–Héroult process converts alumina into metal. Austrian chemist Carl Joseph Bayer discovered a way of purifying bauxite to yield alumina, now known as the Bayer process, in 1889. Modern production of the aluminium metal is based on the Bayer and Hall–Héroult processes. Prices of aluminium dropped and aluminium became widely used in jewelry, everyday items, eyeglass frames, optical instruments, tableware, and foil in the 1890s and early 20th century. Aluminium's ability to form hard yet light alloys with other metals provided the metal with many uses at the time. During World War I, major governments demanded large shipments of aluminium for light strong airframes; during World War II, demand by major governments for aviation was even higher. By the mid-20th century, aluminium had become a part of everyday life and an essential component of housewares. In 1954, production of aluminium surpassed that of copper, historically second in production only to iron, making it the most produced non-ferrous metal. During the mid-20th century, aluminium emerged as a civil engineering material, with building applications in both basic construction and interior finish work, and increasingly being used in military engineering, for both airplanes and land armor vehicle engines. Earth's first artificial satellite, launched in 1957, consisted of two separate aluminium semi-spheres joined and all subsequent space vehicles have used aluminium to some extent. The aluminium can was invented in 1956 and employed as a storage for drinks in 1958. Throughout the 20th century, the production of aluminium rose rapidly: while the world production of aluminium in 1900 was 6,800 metric tons, the annual production first exceeded 100,000 metric tons in 1916; 1,000,000 tons in 1941; 10,000,000 tons in 1971. In the 1970s, the increased demand for aluminium made it an exchange commodity; it entered the London Metal Exchange, the oldest industrial metal exchange in the world, in 1978. The output continued to grow: the annual production of aluminium exceeded 50,000,000 metric tons in 2013.

The real price for aluminium declined from $14,000 per metric ton in 1900 to $2,340 in 1948 (in 1998 United States dollars). Extraction and processing costs were lowered over technological progress and the scale of the economies. However, the need to exploit lower-grade poorer quality deposits and the use of fast increasing input costs (above all, energy) increased the net cost of aluminium; the real price began to grow in the 1970s with the rise of energy cost. Production moved from the industrialized countries to countries where production was cheaper. Production costs in the late 20th century changed because of advances in technology, lower energy prices, exchange rates of the United States dollar, and alumina prices. The BRIC countries' combined share in primary production and primary consumption grew substantially in the first decade of the 21st century. China is accumulating an especially large share of the world's production thanks to an abundance of resources, cheap energy, and governmental stimuli; it also increased its consumption share from 2% in 1972 to 40% in 2010. In the United States, Western Europe, and Japan, most aluminium was consumed in transportation, engineering, construction, and packaging. In 2021, prices for industrial metals such as aluminium have soared to near-record levels as energy shortages in China drive up costs for electricity. Etymology The names aluminium and aluminum are derived from the word alumine, an obsolete term for alumina, a naturally occurring oxide of aluminium. Alumine was borrowed from French, which in turn derived it from alumen, the classical Latin name for alum, the mineral from which it was collected. The Latin word alumen stems from the Proto-Indo-European root *alu- meaning "bitter" or "beer". Coinage British chemist Humphry Davy, who performed a number of experiments aimed to isolate the metal, is credited as the person who named the element. The first name proposed for the metal to be isolated from alum was alumium, which Davy suggested in an 1808 article on his electrochemical research, published in Philosophical Transactions of the Royal Society. It appeared that the name was coined from the English word alum and the Latin suffix -ium; however, it was customary at the time that the elements should have names originating in the Latin language, and as such, this name was not adopted universally. This name was criticized by contemporary chemists from France, Germany, and Sweden, who insisted the metal should be named for the oxide, alumina, from which it would be isolated. The English word name alum does not directly reference the Latin language, whereas alumine/alumina easily references the Latin word alumen (upon declension, alumen changes to alumin-). One example was a writing in French by Swedish chemist Jöns Jacob Berzelius titled Essai sur la Nomenclature chimique, published in July 1811; in this essay, among other things, Berzelius used the name aluminium for the element that would be synthesized from alum. (Another article in the same journal issue also refers to the metal whose oxide forms the basis of sapphire as to aluminium.)

The real price for aluminium declined from $14,000 per metric ton in 1900 to $2,340 in 1948 (in 1998 United States dollars). Extraction and processing costs were lowered over technological progress and the scale of the economies. However, the need to exploit lower-grade poorer quality deposits and the use of fast increasing input costs (above all, energy) increased the net cost of aluminium; the real price began to grow in the 1970s with the rise of energy cost. Production moved from the industrialized countries to countries where production was cheaper. Production costs in the late 20th century changed because of advances in technology, lower energy prices, exchange rates of the United States dollar, and alumina prices. The BRIC countries' combined share in primary production and primary consumption grew substantially in the first decade of the 21st century. China is accumulating an especially large share of the world's production thanks to an abundance of resources, cheap energy, and governmental stimuli; it also increased its consumption share from 2% in 1972 to 40% in 2010. In the United States, Western Europe, and Japan, most aluminium was consumed in transportation, engineering, construction, and packaging. In 2021, prices for industrial metals such as aluminium have soared to near-record levels as energy shortages in China drive up costs for electricity. Etymology The names aluminium and aluminum are derived from the word alumine, an obsolete term for alumina, a naturally occurring oxide of aluminium. Alumine was borrowed from French, which in turn derived it from alumen, the classical Latin name for alum, the mineral from which it was collected. The Latin word alumen stems from the Proto-Indo-European root *alu- meaning "bitter" or "beer". Coinage British chemist Humphry Davy, who performed a number of experiments aimed to isolate the metal, is credited as the person who named the element. The first name proposed for the metal to be isolated from alum was alumium, which Davy suggested in an 1808 article on his electrochemical research, published in Philosophical Transactions of the Royal Society. It appeared that the name was coined from the English word alum and the Latin suffix -ium; however, it was customary at the time that the elements should have names originating in the Latin language, and as such, this name was not adopted universally. This name was criticized by contemporary chemists from France, Germany, and Sweden, who insisted the metal should be named for the oxide, alumina, from which it would be isolated. The English word name alum does not directly reference the Latin language, whereas alumine/alumina easily references the Latin word alumen (upon declension, alumen changes to alumin-). One example was a writing in French by Swedish chemist Jöns Jacob Berzelius titled Essai sur la Nomenclature chimique, published in July 1811; in this essay, among other things, Berzelius used the name aluminium for the element that would be synthesized from alum. (Another article in the same journal issue also refers to the metal whose oxide forms the basis of sapphire as to aluminium.)

The real price for aluminium declined from $14,000 per metric ton in 1900 to $2,340 in 1948 (in 1998 United States dollars). Extraction and processing costs were lowered over technological progress and the scale of the economies. However, the need to exploit lower-grade poorer quality deposits and the use of fast increasing input costs (above all, energy) increased the net cost of aluminium; the real price began to grow in the 1970s with the rise of energy cost. Production moved from the industrialized countries to countries where production was cheaper. Production costs in the late 20th century changed because of advances in technology, lower energy prices, exchange rates of the United States dollar, and alumina prices. The BRIC countries' combined share in primary production and primary consumption grew substantially in the first decade of the 21st century. China is accumulating an especially large share of the world's production thanks to an abundance of resources, cheap energy, and governmental stimuli; it also increased its consumption share from 2% in 1972 to 40% in 2010. In the United States, Western Europe, and Japan, most aluminium was consumed in transportation, engineering, construction, and packaging. In 2021, prices for industrial metals such as aluminium have soared to near-record levels as energy shortages in China drive up costs for electricity. Etymology The names aluminium and aluminum are derived from the word alumine, an obsolete term for alumina, a naturally occurring oxide of aluminium. Alumine was borrowed from French, which in turn derived it from alumen, the classical Latin name for alum, the mineral from which it was collected. The Latin word alumen stems from the Proto-Indo-European root *alu- meaning "bitter" or "beer". Coinage British chemist Humphry Davy, who performed a number of experiments aimed to isolate the metal, is credited as the person who named the element. The first name proposed for the metal to be isolated from alum was alumium, which Davy suggested in an 1808 article on his electrochemical research, published in Philosophical Transactions of the Royal Society. It appeared that the name was coined from the English word alum and the Latin suffix -ium; however, it was customary at the time that the elements should have names originating in the Latin language, and as such, this name was not adopted universally. This name was criticized by contemporary chemists from France, Germany, and Sweden, who insisted the metal should be named for the oxide, alumina, from which it would be isolated. The English word name alum does not directly reference the Latin language, whereas alumine/alumina easily references the Latin word alumen (upon declension, alumen changes to alumin-). One example was a writing in French by Swedish chemist Jöns Jacob Berzelius titled Essai sur la Nomenclature chimique, published in July 1811; in this essay, among other things, Berzelius used the name aluminium for the element that would be synthesized from alum. (Another article in the same journal issue also refers to the metal whose oxide forms the basis of sapphire as to aluminium.)

A January 1811 summary of one of Davy's lectures at the Royal Society mentioned the name aluminium as a possibility. The following year, Davy published a chemistry textbook in which he used the spelling aluminum. Both spellings have coexisted since; however, their usage has split by region: aluminum is the primary spelling in the United States and Canada while aluminium is in the rest of the English-speaking world. Spelling In 1812, British scientist Thomas Young wrote an anonymous review of Davy's book, in which he proposed the name aluminium instead of aluminum, which he felt had a "less classical sound". This name did catch on: while the spelling was occasionally used in Britain, the American scientific language used from the start. Most scientists used throughout the world in the 19th century, and it was entrenched in many other European languages, such as French, German, or Dutch. In 1828, American lexicographer Noah Webster used exclusively the aluminum spelling in his American Dictionary of the English Language. In the 1830s, the spelling started to gain usage in the United States; by the 1860s, it had become the more common spelling there outside science. In 1892, Hall used the spelling in his advertising handbill for his new electrolytic method of producing the metal, despite his constant use of the spelling in all the patents he filed between 1886 and 1903. It remains unknown whether this spelling was introduced by mistake or intentionally; however, Hall preferred aluminum since its introduction because it resembled platinum, the name of a prestigious metal. By 1890, both spellings had been common in the U.S. overall, the spelling being slightly more common; by 1895, the situation had reversed; by 1900, aluminum had become twice as common as aluminium; during the following decade, the spelling dominated American usage. In 1925, the American Chemical Society adopted this spelling. The International Union of Pure and Applied Chemistry (IUPAC) adopted aluminium as the standard international name for the element in 1990. In 1993, they recognized aluminum as an acceptable variant; the most recent 2005 edition of the IUPAC nomenclature of inorganic chemistry acknowledges this spelling as well. IUPAC official publications use the spelling as primary but list both where appropriate. Production and refinement The production of aluminium starts with the extraction of bauxite rock from the ground. The bauxite is processed and transformed using the Bayer process into alumina, which is then processed using the Hall–Héroult process, resulting in the final aluminium metal. Aluminium production is highly energy-consuming, and so the producers tend to locate smelters in places where electric power is both plentiful and inexpensive. As of 2019, the world's largest smelters of aluminium are located in China, India, Russia, Canada, and the United Arab Emirates, while China is by far the top producer of aluminium with a world share of fifty-five percent. According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of aluminium in use in society (i.e. in cars, buildings, electronics, etc.)

A January 1811 summary of one of Davy's lectures at the Royal Society mentioned the name aluminium as a possibility. The following year, Davy published a chemistry textbook in which he used the spelling aluminum. Both spellings have coexisted since; however, their usage has split by region: aluminum is the primary spelling in the United States and Canada while aluminium is in the rest of the English-speaking world. Spelling In 1812, British scientist Thomas Young wrote an anonymous review of Davy's book, in which he proposed the name aluminium instead of aluminum, which he felt had a "less classical sound". This name did catch on: while the spelling was occasionally used in Britain, the American scientific language used from the start. Most scientists used throughout the world in the 19th century, and it was entrenched in many other European languages, such as French, German, or Dutch. In 1828, American lexicographer Noah Webster used exclusively the aluminum spelling in his American Dictionary of the English Language. In the 1830s, the spelling started to gain usage in the United States; by the 1860s, it had become the more common spelling there outside science. In 1892, Hall used the spelling in his advertising handbill for his new electrolytic method of producing the metal, despite his constant use of the spelling in all the patents he filed between 1886 and 1903. It remains unknown whether this spelling was introduced by mistake or intentionally; however, Hall preferred aluminum since its introduction because it resembled platinum, the name of a prestigious metal. By 1890, both spellings had been common in the U.S. overall, the spelling being slightly more common; by 1895, the situation had reversed; by 1900, aluminum had become twice as common as aluminium; during the following decade, the spelling dominated American usage. In 1925, the American Chemical Society adopted this spelling. The International Union of Pure and Applied Chemistry (IUPAC) adopted aluminium as the standard international name for the element in 1990. In 1993, they recognized aluminum as an acceptable variant; the most recent 2005 edition of the IUPAC nomenclature of inorganic chemistry acknowledges this spelling as well. IUPAC official publications use the spelling as primary but list both where appropriate. Production and refinement The production of aluminium starts with the extraction of bauxite rock from the ground. The bauxite is processed and transformed using the Bayer process into alumina, which is then processed using the Hall–Héroult process, resulting in the final aluminium metal. Aluminium production is highly energy-consuming, and so the producers tend to locate smelters in places where electric power is both plentiful and inexpensive. As of 2019, the world's largest smelters of aluminium are located in China, India, Russia, Canada, and the United Arab Emirates, while China is by far the top producer of aluminium with a world share of fifty-five percent. According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of aluminium in use in society (i.e. in cars, buildings, electronics, etc.)

A January 1811 summary of one of Davy's lectures at the Royal Society mentioned the name aluminium as a possibility. The following year, Davy published a chemistry textbook in which he used the spelling aluminum. Both spellings have coexisted since; however, their usage has split by region: aluminum is the primary spelling in the United States and Canada while aluminium is in the rest of the English-speaking world. Spelling In 1812, British scientist Thomas Young wrote an anonymous review of Davy's book, in which he proposed the name aluminium instead of aluminum, which he felt had a "less classical sound". This name did catch on: while the spelling was occasionally used in Britain, the American scientific language used from the start. Most scientists used throughout the world in the 19th century, and it was entrenched in many other European languages, such as French, German, or Dutch. In 1828, American lexicographer Noah Webster used exclusively the aluminum spelling in his American Dictionary of the English Language. In the 1830s, the spelling started to gain usage in the United States; by the 1860s, it had become the more common spelling there outside science. In 1892, Hall used the spelling in his advertising handbill for his new electrolytic method of producing the metal, despite his constant use of the spelling in all the patents he filed between 1886 and 1903. It remains unknown whether this spelling was introduced by mistake or intentionally; however, Hall preferred aluminum since its introduction because it resembled platinum, the name of a prestigious metal. By 1890, both spellings had been common in the U.S. overall, the spelling being slightly more common; by 1895, the situation had reversed; by 1900, aluminum had become twice as common as aluminium; during the following decade, the spelling dominated American usage. In 1925, the American Chemical Society adopted this spelling. The International Union of Pure and Applied Chemistry (IUPAC) adopted aluminium as the standard international name for the element in 1990. In 1993, they recognized aluminum as an acceptable variant; the most recent 2005 edition of the IUPAC nomenclature of inorganic chemistry acknowledges this spelling as well. IUPAC official publications use the spelling as primary but list both where appropriate. Production and refinement The production of aluminium starts with the extraction of bauxite rock from the ground. The bauxite is processed and transformed using the Bayer process into alumina, which is then processed using the Hall–Héroult process, resulting in the final aluminium metal. Aluminium production is highly energy-consuming, and so the producers tend to locate smelters in places where electric power is both plentiful and inexpensive. As of 2019, the world's largest smelters of aluminium are located in China, India, Russia, Canada, and the United Arab Emirates, while China is by far the top producer of aluminium with a world share of fifty-five percent. According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of aluminium in use in society (i.e. in cars, buildings, electronics, etc.)

is . Much of this is in more-developed countries ( per capita) rather than less-developed countries ( per capita). Bayer process Bauxite is converted to alumina by the Bayer process. Bauxite is blended for uniform composition and then is ground. The resulting slurry is mixed with a hot solution of sodium hydroxide; the mixture is then treated in a digester vessel at a pressure well above atmospheric, dissolving the aluminium hydroxide in bauxite while converting impurities into relatively insoluble compounds: After this reaction, the slurry is at a temperature above its atmospheric boiling point. It is cooled by removing steam as pressure is reduced. The bauxite residue is separated from the solution and discarded. The solution, free of solids, is seeded with small crystals of aluminium hydroxide; this causes decomposition of the [Al(OH)4]− ions to aluminium hydroxide. After about half of aluminium has precipitated, the mixture is sent to classifiers. Small crystals of aluminium hydroxide are collected to serve as seeding agents; coarse particles are converted to alumina by heating; the excess solution is removed by evaporation, (if needed) purified, and recycled. Hall–Héroult process The conversion of alumina to aluminium metal is achieved by the Hall–Héroult process. In this energy-intensive process, a solution of alumina in a molten () mixture of cryolite (Na3AlF6) with calcium fluoride is electrolyzed to produce metallic aluminium. The liquid aluminium metal sinks to the bottom of the solution and is tapped off, and usually cast into large blocks called aluminium billets for further processing. Anodes of the electrolysis cell are made of carbon—the most resistant material against fluoride corrosion—and either bake at the process or are prebaked. The former, also called Söderberg anodes, are less power-efficient and fumes released during baking are costly to collect, which is why they are being replaced by prebaked anodes even though they save the power, energy, and labor to prebake the cathodes. Carbon for anodes should be preferably pure so that neither aluminium nor the electrolyte is contaminated with ash. Despite carbon's resistivity against corrosion, it is still consumed at a rate of 0.4–0.5 kg per each kilogram of produced aluminium. Cathodes are made of anthracite; high purity for them is not required because impurities leach only very slowly. The cathode is consumed at a rate of 0.02–0.04 kg per each kilogram of produced aluminium. A cell is usually terminated after 2–6 years following a failure of the cathode. The Hall–Heroult process produces aluminium with a purity of above 99%. Further purification can be done by the Hoopes process. This process involves the electrolysis of molten aluminium with a sodium, barium, and aluminium fluoride electrolyte. The resulting aluminium has a purity of 99.99%. Electric power represents about 20 to 40% of the cost of producing aluminium, depending on the location of the smelter. Aluminium production consumes roughly 5% of electricity generated in the United States. Because of this, alternatives to the Hall–Héroult process have been researched, but none has turned out to be economically feasible.

is . Much of this is in more-developed countries ( per capita) rather than less-developed countries ( per capita). Bayer process Bauxite is converted to alumina by the Bayer process. Bauxite is blended for uniform composition and then is ground. The resulting slurry is mixed with a hot solution of sodium hydroxide; the mixture is then treated in a digester vessel at a pressure well above atmospheric, dissolving the aluminium hydroxide in bauxite while converting impurities into relatively insoluble compounds: After this reaction, the slurry is at a temperature above its atmospheric boiling point. It is cooled by removing steam as pressure is reduced. The bauxite residue is separated from the solution and discarded. The solution, free of solids, is seeded with small crystals of aluminium hydroxide; this causes decomposition of the [Al(OH)4]− ions to aluminium hydroxide. After about half of aluminium has precipitated, the mixture is sent to classifiers. Small crystals of aluminium hydroxide are collected to serve as seeding agents; coarse particles are converted to alumina by heating; the excess solution is removed by evaporation, (if needed) purified, and recycled. Hall–Héroult process The conversion of alumina to aluminium metal is achieved by the Hall–Héroult process. In this energy-intensive process, a solution of alumina in a molten () mixture of cryolite (Na3AlF6) with calcium fluoride is electrolyzed to produce metallic aluminium. The liquid aluminium metal sinks to the bottom of the solution and is tapped off, and usually cast into large blocks called aluminium billets for further processing. Anodes of the electrolysis cell are made of carbon—the most resistant material against fluoride corrosion—and either bake at the process or are prebaked. The former, also called Söderberg anodes, are less power-efficient and fumes released during baking are costly to collect, which is why they are being replaced by prebaked anodes even though they save the power, energy, and labor to prebake the cathodes. Carbon for anodes should be preferably pure so that neither aluminium nor the electrolyte is contaminated with ash. Despite carbon's resistivity against corrosion, it is still consumed at a rate of 0.4–0.5 kg per each kilogram of produced aluminium. Cathodes are made of anthracite; high purity for them is not required because impurities leach only very slowly. The cathode is consumed at a rate of 0.02–0.04 kg per each kilogram of produced aluminium. A cell is usually terminated after 2–6 years following a failure of the cathode. The Hall–Heroult process produces aluminium with a purity of above 99%. Further purification can be done by the Hoopes process. This process involves the electrolysis of molten aluminium with a sodium, barium, and aluminium fluoride electrolyte. The resulting aluminium has a purity of 99.99%. Electric power represents about 20 to 40% of the cost of producing aluminium, depending on the location of the smelter. Aluminium production consumes roughly 5% of electricity generated in the United States. Because of this, alternatives to the Hall–Héroult process have been researched, but none has turned out to be economically feasible.

is . Much of this is in more-developed countries ( per capita) rather than less-developed countries ( per capita). Bayer process Bauxite is converted to alumina by the Bayer process. Bauxite is blended for uniform composition and then is ground. The resulting slurry is mixed with a hot solution of sodium hydroxide; the mixture is then treated in a digester vessel at a pressure well above atmospheric, dissolving the aluminium hydroxide in bauxite while converting impurities into relatively insoluble compounds: After this reaction, the slurry is at a temperature above its atmospheric boiling point. It is cooled by removing steam as pressure is reduced. The bauxite residue is separated from the solution and discarded. The solution, free of solids, is seeded with small crystals of aluminium hydroxide; this causes decomposition of the [Al(OH)4]− ions to aluminium hydroxide. After about half of aluminium has precipitated, the mixture is sent to classifiers. Small crystals of aluminium hydroxide are collected to serve as seeding agents; coarse particles are converted to alumina by heating; the excess solution is removed by evaporation, (if needed) purified, and recycled. Hall–Héroult process The conversion of alumina to aluminium metal is achieved by the Hall–Héroult process. In this energy-intensive process, a solution of alumina in a molten () mixture of cryolite (Na3AlF6) with calcium fluoride is electrolyzed to produce metallic aluminium. The liquid aluminium metal sinks to the bottom of the solution and is tapped off, and usually cast into large blocks called aluminium billets for further processing. Anodes of the electrolysis cell are made of carbon—the most resistant material against fluoride corrosion—and either bake at the process or are prebaked. The former, also called Söderberg anodes, are less power-efficient and fumes released during baking are costly to collect, which is why they are being replaced by prebaked anodes even though they save the power, energy, and labor to prebake the cathodes. Carbon for anodes should be preferably pure so that neither aluminium nor the electrolyte is contaminated with ash. Despite carbon's resistivity against corrosion, it is still consumed at a rate of 0.4–0.5 kg per each kilogram of produced aluminium. Cathodes are made of anthracite; high purity for them is not required because impurities leach only very slowly. The cathode is consumed at a rate of 0.02–0.04 kg per each kilogram of produced aluminium. A cell is usually terminated after 2–6 years following a failure of the cathode. The Hall–Heroult process produces aluminium with a purity of above 99%. Further purification can be done by the Hoopes process. This process involves the electrolysis of molten aluminium with a sodium, barium, and aluminium fluoride electrolyte. The resulting aluminium has a purity of 99.99%. Electric power represents about 20 to 40% of the cost of producing aluminium, depending on the location of the smelter. Aluminium production consumes roughly 5% of electricity generated in the United States. Because of this, alternatives to the Hall–Héroult process have been researched, but none has turned out to be economically feasible.

Recycling Recovery of the metal through recycling has become an important task of the aluminium industry. Recycling was a low-profile activity until the late 1960s, when the growing use of aluminium beverage cans brought it to public awareness. Recycling involves melting the scrap, a process that requires only 5% of the energy used to produce aluminium from ore, though a significant part (up to 15% of the input material) is lost as dross (ash-like oxide). An aluminium stack melter produces significantly less dross, with values reported below 1%. White dross from primary aluminium production and from secondary recycling operations still contains useful quantities of aluminium that can be extracted industrially. The process produces aluminium billets, together with a highly complex waste material. This waste is difficult to manage. It reacts with water, releasing a mixture of gases (including, among others, hydrogen, acetylene, and ammonia), which spontaneously ignites on contact with air; contact with damp air results in the release of copious quantities of ammonia gas. Despite these difficulties, the waste is used as a filler in asphalt and concrete. Applications Metal The global production of aluminium in 2016 was 58.8 million metric tons. It exceeded that of any other metal except iron (1,231 million metric tons). Aluminium is almost always alloyed, which markedly improves its mechanical properties, especially when tempered. For example, the common aluminium foils and beverage cans are alloys of 92% to 99% aluminium. The main alloying agents are copper, zinc, magnesium, manganese, and silicon (e.g., duralumin) with the levels of other metals in a few percent by weight. Aluminium, both wrought and cast, has been alloyed with: manganese, silicon, magnesium, copper and zinc among others. For example, the Kynal family of alloys was developed by the British chemical manufacturer Imperial Chemical Industries. The major uses for aluminium metal are in: Transportation (automobiles, aircraft, trucks, railway cars, marine vessels, bicycles, spacecraft, etc.). Aluminium is used because of its low density; Packaging (cans, foil, frame, etc.). Aluminium is used because it is non-toxic (see below), non-adsorptive, and splinter-proof; Building and construction (windows, doors, siding, building wire, sheathing, roofing, etc.). Since steel is cheaper, aluminium is used when lightness, corrosion resistance, or engineering features are important; Electricity-related uses (conductor alloys, motors, and generators, transformers, capacitors, etc.). Aluminium is used because it is relatively cheap, highly conductive, has adequate mechanical strength and low density, and resists corrosion; A wide range of household items, from cooking utensils to furniture. Low density, good appearance, ease of fabrication, and durability are the key factors of aluminium usage; Machinery and equipment (processing equipment, pipes, tools). Aluminium is used because of its corrosion resistance, non-pyrophoricity, and mechanical strength. Portable computer cases. Currently rarely used without alloying, but aluminium can be recycled and clean aluminium has residual market value: for example, the used beverage can (UBC) material was used to encase the electronic components of MacBook Air laptop, Pixel 5 smartphone or Summit Lite smartwatch.

Recycling Recovery of the metal through recycling has become an important task of the aluminium industry. Recycling was a low-profile activity until the late 1960s, when the growing use of aluminium beverage cans brought it to public awareness. Recycling involves melting the scrap, a process that requires only 5% of the energy used to produce aluminium from ore, though a significant part (up to 15% of the input material) is lost as dross (ash-like oxide). An aluminium stack melter produces significantly less dross, with values reported below 1%. White dross from primary aluminium production and from secondary recycling operations still contains useful quantities of aluminium that can be extracted industrially. The process produces aluminium billets, together with a highly complex waste material. This waste is difficult to manage. It reacts with water, releasing a mixture of gases (including, among others, hydrogen, acetylene, and ammonia), which spontaneously ignites on contact with air; contact with damp air results in the release of copious quantities of ammonia gas. Despite these difficulties, the waste is used as a filler in asphalt and concrete. Applications Metal The global production of aluminium in 2016 was 58.8 million metric tons. It exceeded that of any other metal except iron (1,231 million metric tons). Aluminium is almost always alloyed, which markedly improves its mechanical properties, especially when tempered. For example, the common aluminium foils and beverage cans are alloys of 92% to 99% aluminium. The main alloying agents are copper, zinc, magnesium, manganese, and silicon (e.g., duralumin) with the levels of other metals in a few percent by weight. Aluminium, both wrought and cast, has been alloyed with: manganese, silicon, magnesium, copper and zinc among others. For example, the Kynal family of alloys was developed by the British chemical manufacturer Imperial Chemical Industries. The major uses for aluminium metal are in: Transportation (automobiles, aircraft, trucks, railway cars, marine vessels, bicycles, spacecraft, etc.). Aluminium is used because of its low density; Packaging (cans, foil, frame, etc.). Aluminium is used because it is non-toxic (see below), non-adsorptive, and splinter-proof; Building and construction (windows, doors, siding, building wire, sheathing, roofing, etc.). Since steel is cheaper, aluminium is used when lightness, corrosion resistance, or engineering features are important; Electricity-related uses (conductor alloys, motors, and generators, transformers, capacitors, etc.). Aluminium is used because it is relatively cheap, highly conductive, has adequate mechanical strength and low density, and resists corrosion; A wide range of household items, from cooking utensils to furniture. Low density, good appearance, ease of fabrication, and durability are the key factors of aluminium usage; Machinery and equipment (processing equipment, pipes, tools). Aluminium is used because of its corrosion resistance, non-pyrophoricity, and mechanical strength. Portable computer cases. Currently rarely used without alloying, but aluminium can be recycled and clean aluminium has residual market value: for example, the used beverage can (UBC) material was used to encase the electronic components of MacBook Air laptop, Pixel 5 smartphone or Summit Lite smartwatch.

Recycling Recovery of the metal through recycling has become an important task of the aluminium industry. Recycling was a low-profile activity until the late 1960s, when the growing use of aluminium beverage cans brought it to public awareness. Recycling involves melting the scrap, a process that requires only 5% of the energy used to produce aluminium from ore, though a significant part (up to 15% of the input material) is lost as dross (ash-like oxide). An aluminium stack melter produces significantly less dross, with values reported below 1%. White dross from primary aluminium production and from secondary recycling operations still contains useful quantities of aluminium that can be extracted industrially. The process produces aluminium billets, together with a highly complex waste material. This waste is difficult to manage. It reacts with water, releasing a mixture of gases (including, among others, hydrogen, acetylene, and ammonia), which spontaneously ignites on contact with air; contact with damp air results in the release of copious quantities of ammonia gas. Despite these difficulties, the waste is used as a filler in asphalt and concrete. Applications Metal The global production of aluminium in 2016 was 58.8 million metric tons. It exceeded that of any other metal except iron (1,231 million metric tons). Aluminium is almost always alloyed, which markedly improves its mechanical properties, especially when tempered. For example, the common aluminium foils and beverage cans are alloys of 92% to 99% aluminium. The main alloying agents are copper, zinc, magnesium, manganese, and silicon (e.g., duralumin) with the levels of other metals in a few percent by weight. Aluminium, both wrought and cast, has been alloyed with: manganese, silicon, magnesium, copper and zinc among others. For example, the Kynal family of alloys was developed by the British chemical manufacturer Imperial Chemical Industries. The major uses for aluminium metal are in: Transportation (automobiles, aircraft, trucks, railway cars, marine vessels, bicycles, spacecraft, etc.). Aluminium is used because of its low density; Packaging (cans, foil, frame, etc.). Aluminium is used because it is non-toxic (see below), non-adsorptive, and splinter-proof; Building and construction (windows, doors, siding, building wire, sheathing, roofing, etc.). Since steel is cheaper, aluminium is used when lightness, corrosion resistance, or engineering features are important; Electricity-related uses (conductor alloys, motors, and generators, transformers, capacitors, etc.). Aluminium is used because it is relatively cheap, highly conductive, has adequate mechanical strength and low density, and resists corrosion; A wide range of household items, from cooking utensils to furniture. Low density, good appearance, ease of fabrication, and durability are the key factors of aluminium usage; Machinery and equipment (processing equipment, pipes, tools). Aluminium is used because of its corrosion resistance, non-pyrophoricity, and mechanical strength. Portable computer cases. Currently rarely used without alloying, but aluminium can be recycled and clean aluminium has residual market value: for example, the used beverage can (UBC) material was used to encase the electronic components of MacBook Air laptop, Pixel 5 smartphone or Summit Lite smartwatch.

Compounds The great majority (about 90%) of aluminium oxide is converted to metallic aluminium. Being a very hard material (Mohs hardness 9), alumina is widely used as an abrasive; being extraordinarily chemically inert, it is useful in highly reactive environments such as high pressure sodium lamps. Aluminium oxide is commonly used as a catalyst for industrial processes; e.g. the Claus process to convert hydrogen sulfide to sulfur in refineries and to alkylate amines. Many industrial catalysts are supported by alumina, meaning that the expensive catalyst material is dispersed over a surface of the inert alumina. Another principal use is as a drying agent or absorbent. Several sulfates of aluminium have industrial and commercial application. Aluminium sulfate (in its hydrate form) is produced on the annual scale of several millions of metric tons. About two-thirds is consumed in water treatment. The next major application is in the manufacture of paper. It is also used as a mordant in dyeing, in pickling seeds, deodorizing of mineral oils, in leather tanning, and in production of other aluminium compounds. Two kinds of alum, ammonium alum and potassium alum, were formerly used as mordants and in leather tanning, but their use has significantly declined following availability of high-purity aluminium sulfate. Anhydrous aluminium chloride is used as a catalyst in chemical and petrochemical industries, the dyeing industry, and in synthesis of various inorganic and organic compounds. Aluminium hydroxychlorides are used in purifying water, in the paper industry, and as antiperspirants. Sodium aluminate is used in treating water and as an accelerator of solidification of cement. Many aluminium compounds have niche applications, for example: Aluminium acetate in solution is used as an astringent. Aluminium phosphate is used in the manufacture of glass, ceramic, pulp and paper products, cosmetics, paints, varnishes, and in dental cement. Aluminium hydroxide is used as an antacid, and mordant; it is used also in water purification, the manufacture of glass and ceramics, and in the waterproofing of fabrics. Lithium aluminium hydride is a powerful reducing agent used in organic chemistry. Organoaluminiums are used as Lewis acids and co-catalysts. Methylaluminoxane is a co-catalyst for Ziegler–Natta olefin polymerization to produce vinyl polymers such as polyethene. Aqueous aluminium ions (such as aqueous aluminium sulfate) are used to treat against fish parasites such as Gyrodactylus salaris. In many vaccines, certain aluminium salts serve as an immune adjuvant (immune response booster) to allow the protein in the vaccine to achieve sufficient potency as an immune stimulant. Biology Despite its widespread occurrence in the Earth's crust, aluminium has no known function in biology. At pH 6–9 (relevant for most natural waters), aluminium precipitates out of water as the hydroxide and is hence not available; most elements behaving this way have no biological role or are toxic. Aluminium salts are nontoxic. Aluminium sulfate has an LD50 of 6207 mg/kg (oral, mouse), which corresponds to 435 grams for an person, though lethality and neurotoxicity differ in their implications. Andrási et al.

Compounds The great majority (about 90%) of aluminium oxide is converted to metallic aluminium. Being a very hard material (Mohs hardness 9), alumina is widely used as an abrasive; being extraordinarily chemically inert, it is useful in highly reactive environments such as high pressure sodium lamps. Aluminium oxide is commonly used as a catalyst for industrial processes; e.g. the Claus process to convert hydrogen sulfide to sulfur in refineries and to alkylate amines. Many industrial catalysts are supported by alumina, meaning that the expensive catalyst material is dispersed over a surface of the inert alumina. Another principal use is as a drying agent or absorbent. Several sulfates of aluminium have industrial and commercial application. Aluminium sulfate (in its hydrate form) is produced on the annual scale of several millions of metric tons. About two-thirds is consumed in water treatment. The next major application is in the manufacture of paper. It is also used as a mordant in dyeing, in pickling seeds, deodorizing of mineral oils, in leather tanning, and in production of other aluminium compounds. Two kinds of alum, ammonium alum and potassium alum, were formerly used as mordants and in leather tanning, but their use has significantly declined following availability of high-purity aluminium sulfate. Anhydrous aluminium chloride is used as a catalyst in chemical and petrochemical industries, the dyeing industry, and in synthesis of various inorganic and organic compounds. Aluminium hydroxychlorides are used in purifying water, in the paper industry, and as antiperspirants. Sodium aluminate is used in treating water and as an accelerator of solidification of cement. Many aluminium compounds have niche applications, for example: Aluminium acetate in solution is used as an astringent. Aluminium phosphate is used in the manufacture of glass, ceramic, pulp and paper products, cosmetics, paints, varnishes, and in dental cement. Aluminium hydroxide is used as an antacid, and mordant; it is used also in water purification, the manufacture of glass and ceramics, and in the waterproofing of fabrics. Lithium aluminium hydride is a powerful reducing agent used in organic chemistry. Organoaluminiums are used as Lewis acids and co-catalysts. Methylaluminoxane is a co-catalyst for Ziegler–Natta olefin polymerization to produce vinyl polymers such as polyethene. Aqueous aluminium ions (such as aqueous aluminium sulfate) are used to treat against fish parasites such as Gyrodactylus salaris. In many vaccines, certain aluminium salts serve as an immune adjuvant (immune response booster) to allow the protein in the vaccine to achieve sufficient potency as an immune stimulant. Biology Despite its widespread occurrence in the Earth's crust, aluminium has no known function in biology. At pH 6–9 (relevant for most natural waters), aluminium precipitates out of water as the hydroxide and is hence not available; most elements behaving this way have no biological role or are toxic. Aluminium salts are nontoxic. Aluminium sulfate has an LD50 of 6207 mg/kg (oral, mouse), which corresponds to 435 grams for an person, though lethality and neurotoxicity differ in their implications. Andrási et al.

Compounds The great majority (about 90%) of aluminium oxide is converted to metallic aluminium. Being a very hard material (Mohs hardness 9), alumina is widely used as an abrasive; being extraordinarily chemically inert, it is useful in highly reactive environments such as high pressure sodium lamps. Aluminium oxide is commonly used as a catalyst for industrial processes; e.g. the Claus process to convert hydrogen sulfide to sulfur in refineries and to alkylate amines. Many industrial catalysts are supported by alumina, meaning that the expensive catalyst material is dispersed over a surface of the inert alumina. Another principal use is as a drying agent or absorbent. Several sulfates of aluminium have industrial and commercial application. Aluminium sulfate (in its hydrate form) is produced on the annual scale of several millions of metric tons. About two-thirds is consumed in water treatment. The next major application is in the manufacture of paper. It is also used as a mordant in dyeing, in pickling seeds, deodorizing of mineral oils, in leather tanning, and in production of other aluminium compounds. Two kinds of alum, ammonium alum and potassium alum, were formerly used as mordants and in leather tanning, but their use has significantly declined following availability of high-purity aluminium sulfate. Anhydrous aluminium chloride is used as a catalyst in chemical and petrochemical industries, the dyeing industry, and in synthesis of various inorganic and organic compounds. Aluminium hydroxychlorides are used in purifying water, in the paper industry, and as antiperspirants. Sodium aluminate is used in treating water and as an accelerator of solidification of cement. Many aluminium compounds have niche applications, for example: Aluminium acetate in solution is used as an astringent. Aluminium phosphate is used in the manufacture of glass, ceramic, pulp and paper products, cosmetics, paints, varnishes, and in dental cement. Aluminium hydroxide is used as an antacid, and mordant; it is used also in water purification, the manufacture of glass and ceramics, and in the waterproofing of fabrics. Lithium aluminium hydride is a powerful reducing agent used in organic chemistry. Organoaluminiums are used as Lewis acids and co-catalysts. Methylaluminoxane is a co-catalyst for Ziegler–Natta olefin polymerization to produce vinyl polymers such as polyethene. Aqueous aluminium ions (such as aqueous aluminium sulfate) are used to treat against fish parasites such as Gyrodactylus salaris. In many vaccines, certain aluminium salts serve as an immune adjuvant (immune response booster) to allow the protein in the vaccine to achieve sufficient potency as an immune stimulant. Biology Despite its widespread occurrence in the Earth's crust, aluminium has no known function in biology. At pH 6–9 (relevant for most natural waters), aluminium precipitates out of water as the hydroxide and is hence not available; most elements behaving this way have no biological role or are toxic. Aluminium salts are nontoxic. Aluminium sulfate has an LD50 of 6207 mg/kg (oral, mouse), which corresponds to 435 grams for an person, though lethality and neurotoxicity differ in their implications. Andrási et al.

discovered "significantly higher Aluminum" content in some brain regions when necroscopies of subjects with Alzheimer disease were compared to subjects without. Aluminium chelates with glyphosate. Toxicity Aluminium is classified as a non-carcinogen by the United States Department of Health and Human Services. A review published in 1988 said that there was little evidence that normal exposure to aluminium presents a risk to healthy adult, and a 2014 multi-element toxicology review was unable to find deleterious effects of aluminium consumed in amounts not greater than 40 mg/day per kg of body mass. Most aluminium consumed will leave the body in feces; most of the small part of it that enters the bloodstream, will be excreted via urine; nevertheless some aluminium does pass the blood-brain barrier and is lodged preferentially in the brains of Alzheimer's patients. Evidence published in 1989 indicates that, for Alzheimer's patients, aluminium may act by electrostatically crosslinking proteins, thus down-regulating genes in the superior temporal gyrus. Effects Aluminium, although rarely, can cause vitamin D-resistant osteomalacia, erythropoietin-resistant microcytic anemia, and central nervous system alterations. People with kidney insufficiency are especially at a risk. Chronic ingestion of hydrated aluminium silicates (for excess gastric acidity control) may result in aluminium binding to intestinal contents and increased elimination of other metals, such as iron or zinc; sufficiently high doses (>50 g/day) can cause anemia. During the 1988 Camelford water pollution incident people in Camelford had their drinking water contaminated with aluminium sulfate for several weeks. A final report into the incident in 2013 concluded it was unlikely that this had caused long-term health problems. Aluminium has been suspected of being a possible cause of Alzheimer's disease, but research into this for over 40 years has found, , no good evidence of causal effect. Aluminium increases estrogen-related gene expression in human breast cancer cells cultured in the laboratory. In very high doses, aluminium is associated with altered function of the blood–brain barrier. A small percentage of people have contact allergies to aluminium and experience itchy red rashes, headache, muscle pain, joint pain, poor memory, insomnia, depression, asthma, irritable bowel syndrome, or other symptoms upon contact with products containing aluminium. Exposure to powdered aluminium or aluminium welding fumes can cause pulmonary fibrosis. Fine aluminium powder can ignite or explode, posing another workplace hazard. Exposure routes Food is the main source of aluminium. Drinking water contains more aluminium than solid food; however, aluminium in food may be absorbed more than aluminium from water. Major sources of human oral exposure to aluminium include food (due to its use in food additives, food and beverage packaging, and cooking utensils), drinking water (due to its use in municipal water treatment), and aluminium-containing medications (particularly antacid/antiulcer and buffered aspirin formulations). Dietary exposure in Europeans averages to 0.2–1.5 mg/kg/week but can be as high as 2.3 mg/kg/week. Higher exposure levels of aluminium are mostly limited to miners, aluminium production workers, and dialysis patients. Consumption of antacids, antiperspirants, vaccines, and cosmetics provide possible routes of exposure.

discovered "significantly higher Aluminum" content in some brain regions when necroscopies of subjects with Alzheimer disease were compared to subjects without. Aluminium chelates with glyphosate. Toxicity Aluminium is classified as a non-carcinogen by the United States Department of Health and Human Services. A review published in 1988 said that there was little evidence that normal exposure to aluminium presents a risk to healthy adult, and a 2014 multi-element toxicology review was unable to find deleterious effects of aluminium consumed in amounts not greater than 40 mg/day per kg of body mass. Most aluminium consumed will leave the body in feces; most of the small part of it that enters the bloodstream, will be excreted via urine; nevertheless some aluminium does pass the blood-brain barrier and is lodged preferentially in the brains of Alzheimer's patients. Evidence published in 1989 indicates that, for Alzheimer's patients, aluminium may act by electrostatically crosslinking proteins, thus down-regulating genes in the superior temporal gyrus. Effects Aluminium, although rarely, can cause vitamin D-resistant osteomalacia, erythropoietin-resistant microcytic anemia, and central nervous system alterations. People with kidney insufficiency are especially at a risk. Chronic ingestion of hydrated aluminium silicates (for excess gastric acidity control) may result in aluminium binding to intestinal contents and increased elimination of other metals, such as iron or zinc; sufficiently high doses (>50 g/day) can cause anemia. During the 1988 Camelford water pollution incident people in Camelford had their drinking water contaminated with aluminium sulfate for several weeks. A final report into the incident in 2013 concluded it was unlikely that this had caused long-term health problems. Aluminium has been suspected of being a possible cause of Alzheimer's disease, but research into this for over 40 years has found, , no good evidence of causal effect. Aluminium increases estrogen-related gene expression in human breast cancer cells cultured in the laboratory. In very high doses, aluminium is associated with altered function of the blood–brain barrier. A small percentage of people have contact allergies to aluminium and experience itchy red rashes, headache, muscle pain, joint pain, poor memory, insomnia, depression, asthma, irritable bowel syndrome, or other symptoms upon contact with products containing aluminium. Exposure to powdered aluminium or aluminium welding fumes can cause pulmonary fibrosis. Fine aluminium powder can ignite or explode, posing another workplace hazard. Exposure routes Food is the main source of aluminium. Drinking water contains more aluminium than solid food; however, aluminium in food may be absorbed more than aluminium from water. Major sources of human oral exposure to aluminium include food (due to its use in food additives, food and beverage packaging, and cooking utensils), drinking water (due to its use in municipal water treatment), and aluminium-containing medications (particularly antacid/antiulcer and buffered aspirin formulations). Dietary exposure in Europeans averages to 0.2–1.5 mg/kg/week but can be as high as 2.3 mg/kg/week. Higher exposure levels of aluminium are mostly limited to miners, aluminium production workers, and dialysis patients. Consumption of antacids, antiperspirants, vaccines, and cosmetics provide possible routes of exposure.

discovered "significantly higher Aluminum" content in some brain regions when necroscopies of subjects with Alzheimer disease were compared to subjects without. Aluminium chelates with glyphosate. Toxicity Aluminium is classified as a non-carcinogen by the United States Department of Health and Human Services. A review published in 1988 said that there was little evidence that normal exposure to aluminium presents a risk to healthy adult, and a 2014 multi-element toxicology review was unable to find deleterious effects of aluminium consumed in amounts not greater than 40 mg/day per kg of body mass. Most aluminium consumed will leave the body in feces; most of the small part of it that enters the bloodstream, will be excreted via urine; nevertheless some aluminium does pass the blood-brain barrier and is lodged preferentially in the brains of Alzheimer's patients. Evidence published in 1989 indicates that, for Alzheimer's patients, aluminium may act by electrostatically crosslinking proteins, thus down-regulating genes in the superior temporal gyrus. Effects Aluminium, although rarely, can cause vitamin D-resistant osteomalacia, erythropoietin-resistant microcytic anemia, and central nervous system alterations. People with kidney insufficiency are especially at a risk. Chronic ingestion of hydrated aluminium silicates (for excess gastric acidity control) may result in aluminium binding to intestinal contents and increased elimination of other metals, such as iron or zinc; sufficiently high doses (>50 g/day) can cause anemia. During the 1988 Camelford water pollution incident people in Camelford had their drinking water contaminated with aluminium sulfate for several weeks. A final report into the incident in 2013 concluded it was unlikely that this had caused long-term health problems. Aluminium has been suspected of being a possible cause of Alzheimer's disease, but research into this for over 40 years has found, , no good evidence of causal effect. Aluminium increases estrogen-related gene expression in human breast cancer cells cultured in the laboratory. In very high doses, aluminium is associated with altered function of the blood–brain barrier. A small percentage of people have contact allergies to aluminium and experience itchy red rashes, headache, muscle pain, joint pain, poor memory, insomnia, depression, asthma, irritable bowel syndrome, or other symptoms upon contact with products containing aluminium. Exposure to powdered aluminium or aluminium welding fumes can cause pulmonary fibrosis. Fine aluminium powder can ignite or explode, posing another workplace hazard. Exposure routes Food is the main source of aluminium. Drinking water contains more aluminium than solid food; however, aluminium in food may be absorbed more than aluminium from water. Major sources of human oral exposure to aluminium include food (due to its use in food additives, food and beverage packaging, and cooking utensils), drinking water (due to its use in municipal water treatment), and aluminium-containing medications (particularly antacid/antiulcer and buffered aspirin formulations). Dietary exposure in Europeans averages to 0.2–1.5 mg/kg/week but can be as high as 2.3 mg/kg/week. Higher exposure levels of aluminium are mostly limited to miners, aluminium production workers, and dialysis patients. Consumption of antacids, antiperspirants, vaccines, and cosmetics provide possible routes of exposure.

Consumption of acidic foods or liquids with aluminium enhances aluminium absorption, and maltol has been shown to increase the accumulation of aluminium in nerve and bone tissues. Treatment In case of suspected sudden intake of a large amount of aluminium, the only treatment is deferoxamine mesylate which may be given to help eliminate aluminium from the body by chelation. However, this should be applied with caution as this reduces not only aluminium body levels, but also those of other metals such as copper or iron. Environmental effects High levels of aluminium occur near mining sites; small amounts of aluminium are released to the environment at the coal-fired power plants or incinerators. Aluminium in the air is washed out by the rain or normally settles down but small particles of aluminium remain in the air for a long time. Acidic precipitation is the main natural factor to mobilize aluminium from natural sources and the main reason for the environmental effects of aluminium; however, the main factor of presence of aluminium in salt and freshwater are the industrial processes that also release aluminium into air. In water, aluminium acts as a toxiс agent on gill-breathing animals such as fish when the water is acidic, in which aluminium may precipitate on gills, which causes loss of plasma- and hemolymph ions leading to osmoregulatory failure. Organic complexes of aluminium may be easily absorbed and interfere with metabolism in mammals and birds, even though this rarely happens in practice. Aluminium is primary among the factors that reduce plant growth on acidic soils. Although it is generally harmless to plant growth in pH-neutral soils, in acid soils the concentration of toxic Al3+ cations increases and disturbs root growth and function. Wheat has developed a tolerance to aluminium, releasing organic compounds that bind to harmful aluminium cations. Sorghum is believed to have the same tolerance mechanism. Aluminium production possesses its own challenges to the environment on each step of the production process. The major challenge is the greenhouse gas emissions. These gases result from electrical consumption of the smelters and the byproducts of processing. The most potent of these gases are perfluorocarbons from the smelting process. Released sulfur dioxide is one of the primary precursors of acid rain. A Spanish scientific report from 2001 claimed that the fungus Geotrichum candidum consumes the aluminium in compact discs. Other reports all refer back to that report and there is no supporting original research. Better documented, the bacterium Pseudomonas aeruginosa and the fungus Cladosporium resinae are commonly detected in aircraft fuel tanks that use kerosene-based fuels (not avgas), and laboratory cultures can degrade aluminium. However, these life forms do not directly attack or consume the aluminium; rather, the metal is corroded by microbe waste products. See also Aluminium granules Aluminium joining Aluminium–air battery Panel edge staining Quantum clock Notes References Bibliography Further reading Mimi Sheller, Aluminum Dream: The Making of Light Modernity. Cambridge, Mass. : Massachusetts Institute of Technology Press, 2014.

Consumption of acidic foods or liquids with aluminium enhances aluminium absorption, and maltol has been shown to increase the accumulation of aluminium in nerve and bone tissues. Treatment In case of suspected sudden intake of a large amount of aluminium, the only treatment is deferoxamine mesylate which may be given to help eliminate aluminium from the body by chelation. However, this should be applied with caution as this reduces not only aluminium body levels, but also those of other metals such as copper or iron. Environmental effects High levels of aluminium occur near mining sites; small amounts of aluminium are released to the environment at the coal-fired power plants or incinerators. Aluminium in the air is washed out by the rain or normally settles down but small particles of aluminium remain in the air for a long time. Acidic precipitation is the main natural factor to mobilize aluminium from natural sources and the main reason for the environmental effects of aluminium; however, the main factor of presence of aluminium in salt and freshwater are the industrial processes that also release aluminium into air. In water, aluminium acts as a toxiс agent on gill-breathing animals such as fish when the water is acidic, in which aluminium may precipitate on gills, which causes loss of plasma- and hemolymph ions leading to osmoregulatory failure. Organic complexes of aluminium may be easily absorbed and interfere with metabolism in mammals and birds, even though this rarely happens in practice. Aluminium is primary among the factors that reduce plant growth on acidic soils. Although it is generally harmless to plant growth in pH-neutral soils, in acid soils the concentration of toxic Al3+ cations increases and disturbs root growth and function. Wheat has developed a tolerance to aluminium, releasing organic compounds that bind to harmful aluminium cations. Sorghum is believed to have the same tolerance mechanism. Aluminium production possesses its own challenges to the environment on each step of the production process. The major challenge is the greenhouse gas emissions. These gases result from electrical consumption of the smelters and the byproducts of processing. The most potent of these gases are perfluorocarbons from the smelting process. Released sulfur dioxide is one of the primary precursors of acid rain. A Spanish scientific report from 2001 claimed that the fungus Geotrichum candidum consumes the aluminium in compact discs. Other reports all refer back to that report and there is no supporting original research. Better documented, the bacterium Pseudomonas aeruginosa and the fungus Cladosporium resinae are commonly detected in aircraft fuel tanks that use kerosene-based fuels (not avgas), and laboratory cultures can degrade aluminium. However, these life forms do not directly attack or consume the aluminium; rather, the metal is corroded by microbe waste products. See also Aluminium granules Aluminium joining Aluminium–air battery Panel edge staining Quantum clock Notes References Bibliography Further reading Mimi Sheller, Aluminum Dream: The Making of Light Modernity. Cambridge, Mass. : Massachusetts Institute of Technology Press, 2014.

Consumption of acidic foods or liquids with aluminium enhances aluminium absorption, and maltol has been shown to increase the accumulation of aluminium in nerve and bone tissues. Treatment In case of suspected sudden intake of a large amount of aluminium, the only treatment is deferoxamine mesylate which may be given to help eliminate aluminium from the body by chelation. However, this should be applied with caution as this reduces not only aluminium body levels, but also those of other metals such as copper or iron. Environmental effects High levels of aluminium occur near mining sites; small amounts of aluminium are released to the environment at the coal-fired power plants or incinerators. Aluminium in the air is washed out by the rain or normally settles down but small particles of aluminium remain in the air for a long time. Acidic precipitation is the main natural factor to mobilize aluminium from natural sources and the main reason for the environmental effects of aluminium; however, the main factor of presence of aluminium in salt and freshwater are the industrial processes that also release aluminium into air. In water, aluminium acts as a toxiс agent on gill-breathing animals such as fish when the water is acidic, in which aluminium may precipitate on gills, which causes loss of plasma- and hemolymph ions leading to osmoregulatory failure. Organic complexes of aluminium may be easily absorbed and interfere with metabolism in mammals and birds, even though this rarely happens in practice. Aluminium is primary among the factors that reduce plant growth on acidic soils. Although it is generally harmless to plant growth in pH-neutral soils, in acid soils the concentration of toxic Al3+ cations increases and disturbs root growth and function. Wheat has developed a tolerance to aluminium, releasing organic compounds that bind to harmful aluminium cations. Sorghum is believed to have the same tolerance mechanism. Aluminium production possesses its own challenges to the environment on each step of the production process. The major challenge is the greenhouse gas emissions. These gases result from electrical consumption of the smelters and the byproducts of processing. The most potent of these gases are perfluorocarbons from the smelting process. Released sulfur dioxide is one of the primary precursors of acid rain. A Spanish scientific report from 2001 claimed that the fungus Geotrichum candidum consumes the aluminium in compact discs. Other reports all refer back to that report and there is no supporting original research. Better documented, the bacterium Pseudomonas aeruginosa and the fungus Cladosporium resinae are commonly detected in aircraft fuel tanks that use kerosene-based fuels (not avgas), and laboratory cultures can degrade aluminium. However, these life forms do not directly attack or consume the aluminium; rather, the metal is corroded by microbe waste products. See also Aluminium granules Aluminium joining Aluminium–air battery Panel edge staining Quantum clock Notes References Bibliography Further reading Mimi Sheller, Aluminum Dream: The Making of Light Modernity. Cambridge, Mass. : Massachusetts Institute of Technology Press, 2014.

External links Aluminium at The Periodic Table of Videos (University of Nottingham) Toxic Substances Portal – Aluminum – from the Agency for Toxic Substances and Disease Registry, United States Department of Health and Human Services CDC – NIOSH Pocket Guide to Chemical Hazards – Aluminum World production of primary aluminium, by country Price history of aluminum, according to the IMF History of Aluminium – from the website of the International Aluminium Institute Emedicine – Aluminium Aluminium Electrical conductors Pyrotechnic fuels Airship technology Chemical elements Post-transition metals Reducing agents E-number additives Native element minerals Chemical elements with face-centered cubic structure

External links Aluminium at The Periodic Table of Videos (University of Nottingham) Toxic Substances Portal – Aluminum – from the Agency for Toxic Substances and Disease Registry, United States Department of Health and Human Services CDC – NIOSH Pocket Guide to Chemical Hazards – Aluminum World production of primary aluminium, by country Price history of aluminum, according to the IMF History of Aluminium – from the website of the International Aluminium Institute Emedicine – Aluminium Aluminium Electrical conductors Pyrotechnic fuels Airship technology Chemical elements Post-transition metals Reducing agents E-number additives Native element minerals Chemical elements with face-centered cubic structure

External links Aluminium at The Periodic Table of Videos (University of Nottingham) Toxic Substances Portal – Aluminum – from the Agency for Toxic Substances and Disease Registry, United States Department of Health and Human Services CDC – NIOSH Pocket Guide to Chemical Hazards – Aluminum World production of primary aluminium, by country Price history of aluminum, according to the IMF History of Aluminium – from the website of the International Aluminium Institute Emedicine – Aluminium Aluminium Electrical conductors Pyrotechnic fuels Airship technology Chemical elements Post-transition metals Reducing agents E-number additives Native element minerals Chemical elements with face-centered cubic structure

Advanced Chemistry Advanced Chemistry is a German hip hop group from Heidelberg, a scenic city in Baden-Württemberg, South Germany. Advanced Chemistry was founded in 1987 by Toni L, Linguist, Gee-One, DJ Mike MD (Mike Dippon) and MC Torch. Each member of the group holds German citizenship, and Toni L, Linguist, and Torch are of Italian, Ghanaian, and Haitian backgrounds, respectively. Influenced by North American socially conscious rap and the Native tongues movement, Advanced Chemistry is regarded as one of the main pioneers in German hip hop. They were one of the first groups to rap in German (although their name is in English). Furthermore, their songs tackled controversial social and political issues, distinguishing them from early German hip hop group "Die Fantastischen Vier" (The Fantastic Four), which had a more light-hearted, playful, party image. Career Advanced Chemistry frequently rapped about their lives and experiences as children of immigrants, exposing the marginalization experienced by most ethnic minorities in Germany, and the feelings of frustration and resentment that being denied a German identity can cause. The song "Fremd im eigenen Land" (Foreign in your own nation) was released by Advanced Chemistry in November 1992. The single became a staple in the German hip hop scene. It made a strong statement about the status of immigrants throughout Germany, as the group was composed of multi-national and multi-racial members. The video shows several members brandishing their German passports as a demonstration of their German citizenship to skeptical and unaccepting 'ethnic' Germans. This idea of national identity is important, as many rap artists in Germany have been of foreign origin. These so-called Gastarbeiter (guest workers) children saw breakdance, graffiti, rap music, and hip hop culture as a means of expressing themselves. Since the release of "Fremd im eigenen Land", many other German-language rappers have also tried to confront anti-immigrant ideas and develop themes of citizenship. However, though many ethnic minority youth in Germany find these German identity themes appealing, others view the desire of immigrants to be seen as German negatively, and they have actively sought to revive and recreate concepts of identity in connection to traditional ethnic origins. Advanced Chemistry helped to found the German chapter of the Zulu nation. The rivalry between Advanced Chemistry and Die Fantastischen Vier has served to highlight a dichotomy in the routes that hip hop has taken in becoming a part of the German soundscape. While Die Fantastischen Vier may be said to view hip hop primarily as an aesthetic art form, Advanced Chemistry understand hip hop as being inextricably linked to the social and political circumstances under which it is created. For Advanced Chemistry, hip hop is a “vehicle of general human emancipation,”. In their undertaking of social and political issues, the band introduced the term "Afro-German" into the context of German hip hop, and the theme of race is highlighted in much of their music.

Advanced Chemistry Advanced Chemistry is a German hip hop group from Heidelberg, a scenic city in Baden-Württemberg, South Germany. Advanced Chemistry was founded in 1987 by Toni L, Linguist, Gee-One, DJ Mike MD (Mike Dippon) and MC Torch. Each member of the group holds German citizenship, and Toni L, Linguist, and Torch are of Italian, Ghanaian, and Haitian backgrounds, respectively. Influenced by North American socially conscious rap and the Native tongues movement, Advanced Chemistry is regarded as one of the main pioneers in German hip hop. They were one of the first groups to rap in German (although their name is in English). Furthermore, their songs tackled controversial social and political issues, distinguishing them from early German hip hop group "Die Fantastischen Vier" (The Fantastic Four), which had a more light-hearted, playful, party image. Career Advanced Chemistry frequently rapped about their lives and experiences as children of immigrants, exposing the marginalization experienced by most ethnic minorities in Germany, and the feelings of frustration and resentment that being denied a German identity can cause. The song "Fremd im eigenen Land" (Foreign in your own nation) was released by Advanced Chemistry in November 1992. The single became a staple in the German hip hop scene. It made a strong statement about the status of immigrants throughout Germany, as the group was composed of multi-national and multi-racial members. The video shows several members brandishing their German passports as a demonstration of their German citizenship to skeptical and unaccepting 'ethnic' Germans. This idea of national identity is important, as many rap artists in Germany have been of foreign origin. These so-called Gastarbeiter (guest workers) children saw breakdance, graffiti, rap music, and hip hop culture as a means of expressing themselves. Since the release of "Fremd im eigenen Land", many other German-language rappers have also tried to confront anti-immigrant ideas and develop themes of citizenship. However, though many ethnic minority youth in Germany find these German identity themes appealing, others view the desire of immigrants to be seen as German negatively, and they have actively sought to revive and recreate concepts of identity in connection to traditional ethnic origins. Advanced Chemistry helped to found the German chapter of the Zulu nation. The rivalry between Advanced Chemistry and Die Fantastischen Vier has served to highlight a dichotomy in the routes that hip hop has taken in becoming a part of the German soundscape. While Die Fantastischen Vier may be said to view hip hop primarily as an aesthetic art form, Advanced Chemistry understand hip hop as being inextricably linked to the social and political circumstances under which it is created. For Advanced Chemistry, hip hop is a “vehicle of general human emancipation,”. In their undertaking of social and political issues, the band introduced the term "Afro-German" into the context of German hip hop, and the theme of race is highlighted in much of their music.

With the release of the single “Fremd im eigenen Land”, Advanced Chemistry separated itself from the rest of the rap being produced in Germany. This single was the first of its kind to go beyond simply imitating US rap and addressed the current issues of the time. Fremd im eigenen Land which translates to “foreign in my own country” dealt with the widespread racism that non-white German citizens faced. This change from simple imitation to political commentary was the start of German identification with rap. The sound of “Fremd im eigenen Land” was influenced by the 'wall of noise' created by Public Enemy's producers, The Bomb Squad. After the reunification of Germany, an abundance of anti-immigrant sentiment emerged, as well as attacks on the homes of refugees in the early 1990s. Advanced Chemistry came to prominence in the wake of these actions because of their pro-multicultural society stance in their music. Advanced Chemistry's attitudes revolve around their attempts to create a distinct "Germanness" in hip hop, as opposed to imitating American hip hop as other groups had done. Torch has said, "What the Americans do is exotic for us because we don't live like they do. What they do seems to be more interesting and newer. But not for me. For me it's more exciting to experience my fellow Germans in new contexts...For me, it's interesting to see what the kids try to do that's different from what I know." Advanced Chemistry were the first to use the term "Afro-German" in a hip hop context. This was part of the pro-immigrant political message they sent via their music. While Advanced Chemistry's use of the German language in their rap allows them to make claims to authenticity and true German heritage, bolstering pro-immigration sentiment, their style can also be problematic for immigrant notions of any real ethnic roots. Indeed, part of the Turkish ethnic minority of Frankfurt views Advanced Chemistry's appeal to the German image as a "symbolic betrayal of the right of ethnic minorities to 'roots' or to any expression of cultural heritage." In this sense, their rap represents a complex social discourse internal to the German soundscape in which they attempt to negotiate immigrant assimilation into a xenophobic German culture with the maintenance of their own separate cultural traditions. It is quite possibly the feelings of alienation from the pure-blooded German demographic that drive Advanced Chemistry to attack nationalistic ideologies by asserting their "Germanness" as a group composed primarily of ethnic others. The response to this pseudo-German authenticity can be seen in what Andy Bennett refers to as "alternative forms of local hip hop culture which actively seek to rediscover and, in many cases, reconstruct notions of identity tied to cultural roots." These alternative local hip hop cultures include oriental hip hop, the members of which cling to their Turkish heritage and are confused by Advanced Chemistry's elicitation of a German identity politics to which they technically do not belong.

With the release of the single “Fremd im eigenen Land”, Advanced Chemistry separated itself from the rest of the rap being produced in Germany. This single was the first of its kind to go beyond simply imitating US rap and addressed the current issues of the time. Fremd im eigenen Land which translates to “foreign in my own country” dealt with the widespread racism that non-white German citizens faced. This change from simple imitation to political commentary was the start of German identification with rap. The sound of “Fremd im eigenen Land” was influenced by the 'wall of noise' created by Public Enemy's producers, The Bomb Squad. After the reunification of Germany, an abundance of anti-immigrant sentiment emerged, as well as attacks on the homes of refugees in the early 1990s. Advanced Chemistry came to prominence in the wake of these actions because of their pro-multicultural society stance in their music. Advanced Chemistry's attitudes revolve around their attempts to create a distinct "Germanness" in hip hop, as opposed to imitating American hip hop as other groups had done. Torch has said, "What the Americans do is exotic for us because we don't live like they do. What they do seems to be more interesting and newer. But not for me. For me it's more exciting to experience my fellow Germans in new contexts...For me, it's interesting to see what the kids try to do that's different from what I know." Advanced Chemistry were the first to use the term "Afro-German" in a hip hop context. This was part of the pro-immigrant political message they sent via their music. While Advanced Chemistry's use of the German language in their rap allows them to make claims to authenticity and true German heritage, bolstering pro-immigration sentiment, their style can also be problematic for immigrant notions of any real ethnic roots. Indeed, part of the Turkish ethnic minority of Frankfurt views Advanced Chemistry's appeal to the German image as a "symbolic betrayal of the right of ethnic minorities to 'roots' or to any expression of cultural heritage." In this sense, their rap represents a complex social discourse internal to the German soundscape in which they attempt to negotiate immigrant assimilation into a xenophobic German culture with the maintenance of their own separate cultural traditions. It is quite possibly the feelings of alienation from the pure-blooded German demographic that drive Advanced Chemistry to attack nationalistic ideologies by asserting their "Germanness" as a group composed primarily of ethnic others. The response to this pseudo-German authenticity can be seen in what Andy Bennett refers to as "alternative forms of local hip hop culture which actively seek to rediscover and, in many cases, reconstruct notions of identity tied to cultural roots." These alternative local hip hop cultures include oriental hip hop, the members of which cling to their Turkish heritage and are confused by Advanced Chemistry's elicitation of a German identity politics to which they technically do not belong.

With the release of the single “Fremd im eigenen Land”, Advanced Chemistry separated itself from the rest of the rap being produced in Germany. This single was the first of its kind to go beyond simply imitating US rap and addressed the current issues of the time. Fremd im eigenen Land which translates to “foreign in my own country” dealt with the widespread racism that non-white German citizens faced. This change from simple imitation to political commentary was the start of German identification with rap. The sound of “Fremd im eigenen Land” was influenced by the 'wall of noise' created by Public Enemy's producers, The Bomb Squad. After the reunification of Germany, an abundance of anti-immigrant sentiment emerged, as well as attacks on the homes of refugees in the early 1990s. Advanced Chemistry came to prominence in the wake of these actions because of their pro-multicultural society stance in their music. Advanced Chemistry's attitudes revolve around their attempts to create a distinct "Germanness" in hip hop, as opposed to imitating American hip hop as other groups had done. Torch has said, "What the Americans do is exotic for us because we don't live like they do. What they do seems to be more interesting and newer. But not for me. For me it's more exciting to experience my fellow Germans in new contexts...For me, it's interesting to see what the kids try to do that's different from what I know." Advanced Chemistry were the first to use the term "Afro-German" in a hip hop context. This was part of the pro-immigrant political message they sent via their music. While Advanced Chemistry's use of the German language in their rap allows them to make claims to authenticity and true German heritage, bolstering pro-immigration sentiment, their style can also be problematic for immigrant notions of any real ethnic roots. Indeed, part of the Turkish ethnic minority of Frankfurt views Advanced Chemistry's appeal to the German image as a "symbolic betrayal of the right of ethnic minorities to 'roots' or to any expression of cultural heritage." In this sense, their rap represents a complex social discourse internal to the German soundscape in which they attempt to negotiate immigrant assimilation into a xenophobic German culture with the maintenance of their own separate cultural traditions. It is quite possibly the feelings of alienation from the pure-blooded German demographic that drive Advanced Chemistry to attack nationalistic ideologies by asserting their "Germanness" as a group composed primarily of ethnic others. The response to this pseudo-German authenticity can be seen in what Andy Bennett refers to as "alternative forms of local hip hop culture which actively seek to rediscover and, in many cases, reconstruct notions of identity tied to cultural roots." These alternative local hip hop cultures include oriental hip hop, the members of which cling to their Turkish heritage and are confused by Advanced Chemistry's elicitation of a German identity politics to which they technically do not belong.

This cultural binary illustrates that rap has taken different routes in Germany and that, even among an already isolated immigrant population, there is still disunity and, especially, disagreement on the relative importance of assimilation versus cultural defiance. According to German hip hop enthusiast 9@home, Advanced Chemistry is part of a "hip-hop movement [which] took a clear stance for the minorities and against the [marginalization] of immigrants who...might be German on paper, but not in real life," which speaks to the group's hope of actually being recognized as German citizens and not foreigners, despite their various other ethnic and cultural ties. Influences Advanced Chemistry's work was rooted in German history and the country's specific political realities. However, they also drew inspiration from African-American hip-hop acts like A Tribe Called Quest and Public Enemy, who had helped bring a soulful sound and political consciousness to American hip-hop. One member, Torch, later explicitly listed his references on his solo song "Als (When I Was in School):" "My favorite subject, which was quickly discovered poetry in load Poets, awakens the intellect or policy at Chuck D I'll never forget the lyrics by Public Enemy." Torch goes on to list other American rappers like Biz Markie, Big Daddy Kane and Dr. Dre as influences. Discography 1992 - "Fremd im eigenen Land" (12"/MCD, MZEE) 1993 - "Welcher Pfad führt zur Geschichte" (12"/MCD, MZEE) 1994 - "Operation § 3" (12"/MCD) 1994 - "Dir fehlt der Funk!" (12"/MCD) 1995 - Advanced Chemistry (2xLP/CD) External links Official Website of MC Torch Website of Toni L Official Website of Linguist Official Website DJ Mike MD (Mike Dippon) Website of 360° Records Bibliography El-Tayeb, Fatima “‘If You Cannot Pronounce My Name, You Can Just Call Me Pride.’ Afro-German Activism, Gender, and Hip Hop,” Gender & History15/3(2003):459-485. Felbert, Oliver von. “Die Unbestechlichen.” Spex (March 1993): 50–53. Weheliye, Alexander G. Phonographies:Grooves in Sonic Afro-Modernity, Duke University Press, 2005. References German hip hop groups

This cultural binary illustrates that rap has taken different routes in Germany and that, even among an already isolated immigrant population, there is still disunity and, especially, disagreement on the relative importance of assimilation versus cultural defiance. According to German hip hop enthusiast 9@home, Advanced Chemistry is part of a "hip-hop movement [which] took a clear stance for the minorities and against the [marginalization] of immigrants who...might be German on paper, but not in real life," which speaks to the group's hope of actually being recognized as German citizens and not foreigners, despite their various other ethnic and cultural ties. Influences Advanced Chemistry's work was rooted in German history and the country's specific political realities. However, they also drew inspiration from African-American hip-hop acts like A Tribe Called Quest and Public Enemy, who had helped bring a soulful sound and political consciousness to American hip-hop. One member, Torch, later explicitly listed his references on his solo song "Als (When I Was in School):" "My favorite subject, which was quickly discovered poetry in load Poets, awakens the intellect or policy at Chuck D I'll never forget the lyrics by Public Enemy." Torch goes on to list other American rappers like Biz Markie, Big Daddy Kane and Dr. Dre as influences. Discography 1992 - "Fremd im eigenen Land" (12"/MCD, MZEE) 1993 - "Welcher Pfad führt zur Geschichte" (12"/MCD, MZEE) 1994 - "Operation § 3" (12"/MCD) 1994 - "Dir fehlt der Funk!" (12"/MCD) 1995 - Advanced Chemistry (2xLP/CD) External links Official Website of MC Torch Website of Toni L Official Website of Linguist Official Website DJ Mike MD (Mike Dippon) Website of 360° Records Bibliography El-Tayeb, Fatima “‘If You Cannot Pronounce My Name, You Can Just Call Me Pride.’ Afro-German Activism, Gender, and Hip Hop,” Gender & History15/3(2003):459-485. Felbert, Oliver von. “Die Unbestechlichen.” Spex (March 1993): 50–53. Weheliye, Alexander G. Phonographies:Grooves in Sonic Afro-Modernity, Duke University Press, 2005. References German hip hop groups

This cultural binary illustrates that rap has taken different routes in Germany and that, even among an already isolated immigrant population, there is still disunity and, especially, disagreement on the relative importance of assimilation versus cultural defiance. According to German hip hop enthusiast 9@home, Advanced Chemistry is part of a "hip-hop movement [which] took a clear stance for the minorities and against the [marginalization] of immigrants who...might be German on paper, but not in real life," which speaks to the group's hope of actually being recognized as German citizens and not foreigners, despite their various other ethnic and cultural ties. Influences Advanced Chemistry's work was rooted in German history and the country's specific political realities. However, they also drew inspiration from African-American hip-hop acts like A Tribe Called Quest and Public Enemy, who had helped bring a soulful sound and political consciousness to American hip-hop. One member, Torch, later explicitly listed his references on his solo song "Als (When I Was in School):" "My favorite subject, which was quickly discovered poetry in load Poets, awakens the intellect or policy at Chuck D I'll never forget the lyrics by Public Enemy." Torch goes on to list other American rappers like Biz Markie, Big Daddy Kane and Dr. Dre as influences. Discography 1992 - "Fremd im eigenen Land" (12"/MCD, MZEE) 1993 - "Welcher Pfad führt zur Geschichte" (12"/MCD, MZEE) 1994 - "Operation § 3" (12"/MCD) 1994 - "Dir fehlt der Funk!" (12"/MCD) 1995 - Advanced Chemistry (2xLP/CD) External links Official Website of MC Torch Website of Toni L Official Website of Linguist Official Website DJ Mike MD (Mike Dippon) Website of 360° Records Bibliography El-Tayeb, Fatima “‘If You Cannot Pronounce My Name, You Can Just Call Me Pride.’ Afro-German Activism, Gender, and Hip Hop,” Gender & History15/3(2003):459-485. Felbert, Oliver von. “Die Unbestechlichen.” Spex (March 1993): 50–53. Weheliye, Alexander G. Phonographies:Grooves in Sonic Afro-Modernity, Duke University Press, 2005. References German hip hop groups

Anglican Communion The Anglican Communion is the third largest Christian communion after the Roman Catholic and Eastern Orthodox churches. Founded in 1867 in London, the communion has more than 85 million members within the Church of England and other autocephalous national and regional churches in full communion. The traditional origins of Anglican doctrine are summarised in the Thirty-nine Articles (1571). The Archbishop of Canterbury (currently Justin Welby) in England acts as a focus of unity, recognised as primus inter pares ("first among equals"), but does not exercise authority in Anglican provinces outside of the Church of England. Most, but not all, member churches of the communion are the historic national or regional Anglican churches. The Anglican Communion was officially and formally organised and recognised as such at the Lambeth Conference in 1867 in London under the leadership of Charles Longley, Archbishop of Canterbury. The churches of the Anglican Communion consider themselves to be part of the one, holy, catholic and apostolic church, and to be both catholic and reformed. As in the Church of England itself, the Anglican Communion includes the broad spectrum of beliefs and liturgical practises found in the Evangelical, Central and Anglo-Catholic traditions of Anglicanism. Each national or regional church is fully independent, retaining its own legislative process and episcopal polity under the leadership of local primates. For some adherents, Anglicanism represents a non-papal Catholicism, for others a form of Protestantism though without a guiding figure such as Luther, Knox, Calvin, Zwingli or Wesley, or for yet others a combination of the two. Most of its members live in the Anglosphere of former British territories. Full participation in the sacramental life of each church is available to all communicant members. Because of their historical link to England (ecclesia anglicana means "English church"), some of the member churches are known as "Anglican", such as the Anglican Church of Canada. Others, for example the Church of Ireland and the Scottish and American Episcopal churches, have official names that do not include "Anglican". Additionally, some churches which use the name "Anglican" are not part of the communion. Ecclesiology, polity and ethos The Anglican Communion has no official legal existence nor any governing structure which might exercise authority over the member churches. There is an Anglican Communion Office in London, under the aegis of the Archbishop of Canterbury, but it only serves in a supporting and organisational role. The communion is held together by a shared history, expressed in its ecclesiology, polity and ethos, and also by participation in international consultative bodies. Three elements have been important in holding the communion together: first, the shared ecclesial structure of the component churches, manifested in an episcopal polity maintained through the apostolic succession of bishops and synodical government; second, the principle of belief expressed in worship, investing importance in approved prayer books and their rubrics; and third, the historical documents and the writings of early Anglican divines that have influenced the ethos of the communion.

Anglican Communion The Anglican Communion is the third largest Christian communion after the Roman Catholic and Eastern Orthodox churches. Founded in 1867 in London, the communion has more than 85 million members within the Church of England and other autocephalous national and regional churches in full communion. The traditional origins of Anglican doctrine are summarised in the Thirty-nine Articles (1571). The Archbishop of Canterbury (currently Justin Welby) in England acts as a focus of unity, recognised as primus inter pares ("first among equals"), but does not exercise authority in Anglican provinces outside of the Church of England. Most, but not all, member churches of the communion are the historic national or regional Anglican churches. The Anglican Communion was officially and formally organised and recognised as such at the Lambeth Conference in 1867 in London under the leadership of Charles Longley, Archbishop of Canterbury. The churches of the Anglican Communion consider themselves to be part of the one, holy, catholic and apostolic church, and to be both catholic and reformed. As in the Church of England itself, the Anglican Communion includes the broad spectrum of beliefs and liturgical practises found in the Evangelical, Central and Anglo-Catholic traditions of Anglicanism. Each national or regional church is fully independent, retaining its own legislative process and episcopal polity under the leadership of local primates. For some adherents, Anglicanism represents a non-papal Catholicism, for others a form of Protestantism though without a guiding figure such as Luther, Knox, Calvin, Zwingli or Wesley, or for yet others a combination of the two. Most of its members live in the Anglosphere of former British territories. Full participation in the sacramental life of each church is available to all communicant members. Because of their historical link to England (ecclesia anglicana means "English church"), some of the member churches are known as "Anglican", such as the Anglican Church of Canada. Others, for example the Church of Ireland and the Scottish and American Episcopal churches, have official names that do not include "Anglican". Additionally, some churches which use the name "Anglican" are not part of the communion. Ecclesiology, polity and ethos The Anglican Communion has no official legal existence nor any governing structure which might exercise authority over the member churches. There is an Anglican Communion Office in London, under the aegis of the Archbishop of Canterbury, but it only serves in a supporting and organisational role. The communion is held together by a shared history, expressed in its ecclesiology, polity and ethos, and also by participation in international consultative bodies. Three elements have been important in holding the communion together: first, the shared ecclesial structure of the component churches, manifested in an episcopal polity maintained through the apostolic succession of bishops and synodical government; second, the principle of belief expressed in worship, investing importance in approved prayer books and their rubrics; and third, the historical documents and the writings of early Anglican divines that have influenced the ethos of the communion.

Originally, the Church of England was self-contained and relied for its unity and identity on its own history, its traditional legal and episcopal structure, and its status as an established church of the state. As such, Anglicanism was from the outset a movement with an explicitly episcopal polity, a characteristic that has been vital in maintaining the unity of the communion by conveying the episcopate's role in manifesting visible catholicity and ecumenism. Early in its development following the English Reformation, Anglicanism developed a vernacular prayer book, called the Book of Common Prayer. Unlike other traditions, Anglicanism has never been governed by a magisterium nor by appeal to one founding theologian, nor by an extra-credal summary of doctrine (such as the Westminster Confession of the Presbyterian churches). Instead, Anglicans have typically appealed to the Book of Common Prayer (1662) and its offshoots as a guide to Anglican theology and practise. This has had the effect of inculcating in Anglican identity and confession the principle of lex orandi, lex credendi ("the law of praying [is] the law of believing"). Protracted conflict through the 17th century, with radical Protestants on the one hand and Roman Catholics who recognised the primacy of the Pope on the other, resulted in an association of churches that was both deliberately vague about doctrinal principles, yet bold in developing parameters of acceptable deviation. These parameters were most clearly articulated in the various rubrics of the successive prayer books, as well as the Thirty-Nine Articles of Religion (1563). These articles have historically shaped and continue to direct the ethos of the communion, an ethos reinforced by its interpretation and expansion by such influential early theologians such as Richard Hooker, Lancelot Andrewes and John Cosin. With the expansion of the British Empire the growth of Anglicanism outside Great Britain and Ireland, the communion sought to establish new vehicles of unity. The first major expressions of this were the Lambeth Conferences of the communion's bishops, first convened in 1867 by Charles Longley, the Archbishop of Canterbury. From the beginning, these were not intended to displace the autonomy of the emerging provinces of the communion, but to "discuss matters of practical interest, and pronounce what we deem expedient in resolutions which may serve as safe guides to future action". Chicago Lambeth Quadrilateral One of the enduringly influential early resolutions of the conference was the so-called Chicago-Lambeth Quadrilateral of 1888. Its intent was to provide the basis for discussions of reunion with the Roman Catholic and Orthodox churches, but it had the ancillary effect of establishing parameters of Anglican identity. It establishes four principles with these words: Instruments of communion As mentioned above, the Anglican Communion has no international juridical organisation. The Archbishop of Canterbury's role is strictly symbolic and unifying and the communion's three international bodies are consultative and collaborative, their resolutions having no legal effect on the autonomous provinces of the communion.

Originally, the Church of England was self-contained and relied for its unity and identity on its own history, its traditional legal and episcopal structure, and its status as an established church of the state. As such, Anglicanism was from the outset a movement with an explicitly episcopal polity, a characteristic that has been vital in maintaining the unity of the communion by conveying the episcopate's role in manifesting visible catholicity and ecumenism. Early in its development following the English Reformation, Anglicanism developed a vernacular prayer book, called the Book of Common Prayer. Unlike other traditions, Anglicanism has never been governed by a magisterium nor by appeal to one founding theologian, nor by an extra-credal summary of doctrine (such as the Westminster Confession of the Presbyterian churches). Instead, Anglicans have typically appealed to the Book of Common Prayer (1662) and its offshoots as a guide to Anglican theology and practise. This has had the effect of inculcating in Anglican identity and confession the principle of lex orandi, lex credendi ("the law of praying [is] the law of believing"). Protracted conflict through the 17th century, with radical Protestants on the one hand and Roman Catholics who recognised the primacy of the Pope on the other, resulted in an association of churches that was both deliberately vague about doctrinal principles, yet bold in developing parameters of acceptable deviation. These parameters were most clearly articulated in the various rubrics of the successive prayer books, as well as the Thirty-Nine Articles of Religion (1563). These articles have historically shaped and continue to direct the ethos of the communion, an ethos reinforced by its interpretation and expansion by such influential early theologians such as Richard Hooker, Lancelot Andrewes and John Cosin. With the expansion of the British Empire the growth of Anglicanism outside Great Britain and Ireland, the communion sought to establish new vehicles of unity. The first major expressions of this were the Lambeth Conferences of the communion's bishops, first convened in 1867 by Charles Longley, the Archbishop of Canterbury. From the beginning, these were not intended to displace the autonomy of the emerging provinces of the communion, but to "discuss matters of practical interest, and pronounce what we deem expedient in resolutions which may serve as safe guides to future action". Chicago Lambeth Quadrilateral One of the enduringly influential early resolutions of the conference was the so-called Chicago-Lambeth Quadrilateral of 1888. Its intent was to provide the basis for discussions of reunion with the Roman Catholic and Orthodox churches, but it had the ancillary effect of establishing parameters of Anglican identity. It establishes four principles with these words: Instruments of communion As mentioned above, the Anglican Communion has no international juridical organisation. The Archbishop of Canterbury's role is strictly symbolic and unifying and the communion's three international bodies are consultative and collaborative, their resolutions having no legal effect on the autonomous provinces of the communion.

Originally, the Church of England was self-contained and relied for its unity and identity on its own history, its traditional legal and episcopal structure, and its status as an established church of the state. As such, Anglicanism was from the outset a movement with an explicitly episcopal polity, a characteristic that has been vital in maintaining the unity of the communion by conveying the episcopate's role in manifesting visible catholicity and ecumenism. Early in its development following the English Reformation, Anglicanism developed a vernacular prayer book, called the Book of Common Prayer. Unlike other traditions, Anglicanism has never been governed by a magisterium nor by appeal to one founding theologian, nor by an extra-credal summary of doctrine (such as the Westminster Confession of the Presbyterian churches). Instead, Anglicans have typically appealed to the Book of Common Prayer (1662) and its offshoots as a guide to Anglican theology and practise. This has had the effect of inculcating in Anglican identity and confession the principle of lex orandi, lex credendi ("the law of praying [is] the law of believing"). Protracted conflict through the 17th century, with radical Protestants on the one hand and Roman Catholics who recognised the primacy of the Pope on the other, resulted in an association of churches that was both deliberately vague about doctrinal principles, yet bold in developing parameters of acceptable deviation. These parameters were most clearly articulated in the various rubrics of the successive prayer books, as well as the Thirty-Nine Articles of Religion (1563). These articles have historically shaped and continue to direct the ethos of the communion, an ethos reinforced by its interpretation and expansion by such influential early theologians such as Richard Hooker, Lancelot Andrewes and John Cosin. With the expansion of the British Empire the growth of Anglicanism outside Great Britain and Ireland, the communion sought to establish new vehicles of unity. The first major expressions of this were the Lambeth Conferences of the communion's bishops, first convened in 1867 by Charles Longley, the Archbishop of Canterbury. From the beginning, these were not intended to displace the autonomy of the emerging provinces of the communion, but to "discuss matters of practical interest, and pronounce what we deem expedient in resolutions which may serve as safe guides to future action". Chicago Lambeth Quadrilateral One of the enduringly influential early resolutions of the conference was the so-called Chicago-Lambeth Quadrilateral of 1888. Its intent was to provide the basis for discussions of reunion with the Roman Catholic and Orthodox churches, but it had the ancillary effect of establishing parameters of Anglican identity. It establishes four principles with these words: Instruments of communion As mentioned above, the Anglican Communion has no international juridical organisation. The Archbishop of Canterbury's role is strictly symbolic and unifying and the communion's three international bodies are consultative and collaborative, their resolutions having no legal effect on the autonomous provinces of the communion.

Taken together, however, the four do function as "instruments of communion", since all churches of the communion participate in them. In order of antiquity, they are: The Archbishop of Canterbury functions as the spiritual head of the communion. The archbishop is the focus of unity, since no church claims membership in the Communion without being in communion with him. The present archbishop is Justin Welby. The Lambeth Conference (first held in 1867) is the oldest international consultation. It is a forum for bishops of the communion to reinforce unity and collegiality through manifesting the episcopate, to discuss matters of mutual concern, and to pass resolutions intended to act as guideposts. It is held roughly every 10 years and invitation is by the Archbishop of Canterbury. The Anglican Consultative Council (first met in 1971) was created by a 1968 Lambeth Conference resolution, and meets usually at three-yearly intervals. The council consists of representative bishops, other clergy and laity chosen by the 38 provinces. The body has a permanent secretariat, the Anglican Communion Office, of which the Archbishop of Canterbury is president. The Primates' Meeting (first met in 1979) is the most recent manifestation of international consultation and deliberation, having been first convened by Archbishop Donald Coggan as a forum for "leisurely thought, prayer and deep consultation". Since there is no binding authority in the Anglican Communion, these international bodies are a vehicle for consultation and persuasion. In recent times, persuasion has tipped over into debates over conformity in certain areas of doctrine, discipline, worship and ethics. The most notable example has been the objection of many provinces of the communion (particularly in Africa and Asia) to the changing acceptance of LGBTQ+ individuals in the North American churches (e.g., by blessing same-sex unions and ordaining and consecrating same-sex relationships) and to the process by which changes were undertaken. (See Anglican realignment) Those who objected condemned these actions as unscriptural, unilateral, and without the agreement of the communion prior to these steps being taken. In response, the American Episcopal Church and the Anglican Church of Canada answered that the actions had been undertaken after lengthy scriptural and theological reflection, legally in accordance with their own canons and constitutions and after extensive consultation with the provinces of the communion. The Primates' Meeting voted to request the two churches to withdraw their delegates from the 2005 meeting of the Anglican Consultative Council. Canada and the United States decided to attend the meeting but without exercising their right to vote. They have not been expelled or suspended, since there is no mechanism in this voluntary association to suspend or expel an independent province of the communion. Since membership is based on a province's communion with Canterbury, expulsion would require the Archbishop of Canterbury's refusal to be in communion with the affected jurisdictions.

Taken together, however, the four do function as "instruments of communion", since all churches of the communion participate in them. In order of antiquity, they are: The Archbishop of Canterbury functions as the spiritual head of the communion. The archbishop is the focus of unity, since no church claims membership in the Communion without being in communion with him. The present archbishop is Justin Welby. The Lambeth Conference (first held in 1867) is the oldest international consultation. It is a forum for bishops of the communion to reinforce unity and collegiality through manifesting the episcopate, to discuss matters of mutual concern, and to pass resolutions intended to act as guideposts. It is held roughly every 10 years and invitation is by the Archbishop of Canterbury. The Anglican Consultative Council (first met in 1971) was created by a 1968 Lambeth Conference resolution, and meets usually at three-yearly intervals. The council consists of representative bishops, other clergy and laity chosen by the 38 provinces. The body has a permanent secretariat, the Anglican Communion Office, of which the Archbishop of Canterbury is president. The Primates' Meeting (first met in 1979) is the most recent manifestation of international consultation and deliberation, having been first convened by Archbishop Donald Coggan as a forum for "leisurely thought, prayer and deep consultation". Since there is no binding authority in the Anglican Communion, these international bodies are a vehicle for consultation and persuasion. In recent times, persuasion has tipped over into debates over conformity in certain areas of doctrine, discipline, worship and ethics. The most notable example has been the objection of many provinces of the communion (particularly in Africa and Asia) to the changing acceptance of LGBTQ+ individuals in the North American churches (e.g., by blessing same-sex unions and ordaining and consecrating same-sex relationships) and to the process by which changes were undertaken. (See Anglican realignment) Those who objected condemned these actions as unscriptural, unilateral, and without the agreement of the communion prior to these steps being taken. In response, the American Episcopal Church and the Anglican Church of Canada answered that the actions had been undertaken after lengthy scriptural and theological reflection, legally in accordance with their own canons and constitutions and after extensive consultation with the provinces of the communion. The Primates' Meeting voted to request the two churches to withdraw their delegates from the 2005 meeting of the Anglican Consultative Council. Canada and the United States decided to attend the meeting but without exercising their right to vote. They have not been expelled or suspended, since there is no mechanism in this voluntary association to suspend or expel an independent province of the communion. Since membership is based on a province's communion with Canterbury, expulsion would require the Archbishop of Canterbury's refusal to be in communion with the affected jurisdictions.

Taken together, however, the four do function as "instruments of communion", since all churches of the communion participate in them. In order of antiquity, they are: The Archbishop of Canterbury functions as the spiritual head of the communion. The archbishop is the focus of unity, since no church claims membership in the Communion without being in communion with him. The present archbishop is Justin Welby. The Lambeth Conference (first held in 1867) is the oldest international consultation. It is a forum for bishops of the communion to reinforce unity and collegiality through manifesting the episcopate, to discuss matters of mutual concern, and to pass resolutions intended to act as guideposts. It is held roughly every 10 years and invitation is by the Archbishop of Canterbury. The Anglican Consultative Council (first met in 1971) was created by a 1968 Lambeth Conference resolution, and meets usually at three-yearly intervals. The council consists of representative bishops, other clergy and laity chosen by the 38 provinces. The body has a permanent secretariat, the Anglican Communion Office, of which the Archbishop of Canterbury is president. The Primates' Meeting (first met in 1979) is the most recent manifestation of international consultation and deliberation, having been first convened by Archbishop Donald Coggan as a forum for "leisurely thought, prayer and deep consultation". Since there is no binding authority in the Anglican Communion, these international bodies are a vehicle for consultation and persuasion. In recent times, persuasion has tipped over into debates over conformity in certain areas of doctrine, discipline, worship and ethics. The most notable example has been the objection of many provinces of the communion (particularly in Africa and Asia) to the changing acceptance of LGBTQ+ individuals in the North American churches (e.g., by blessing same-sex unions and ordaining and consecrating same-sex relationships) and to the process by which changes were undertaken. (See Anglican realignment) Those who objected condemned these actions as unscriptural, unilateral, and without the agreement of the communion prior to these steps being taken. In response, the American Episcopal Church and the Anglican Church of Canada answered that the actions had been undertaken after lengthy scriptural and theological reflection, legally in accordance with their own canons and constitutions and after extensive consultation with the provinces of the communion. The Primates' Meeting voted to request the two churches to withdraw their delegates from the 2005 meeting of the Anglican Consultative Council. Canada and the United States decided to attend the meeting but without exercising their right to vote. They have not been expelled or suspended, since there is no mechanism in this voluntary association to suspend or expel an independent province of the communion. Since membership is based on a province's communion with Canterbury, expulsion would require the Archbishop of Canterbury's refusal to be in communion with the affected jurisdictions.

In line with the suggestion of the Windsor Report, Rowan Williams (the then Archbishop of Canterbury) established a working group to examine the feasibility of an Anglican covenant which would articulate the conditions for communion in some fashion. Organisation Provinces The Anglican communion consists of forty-one autonomous provinces each with its own primate and governing structure. These provinces may take the form of national churches (such as in Canada, Uganda, or Japan) or a collection of nations (such as the West Indies, Central Africa, or Southeast Asia). Extraprovincial churches In addition to the forty-one provinces, there are five extraprovincial churches under the metropolitical authority of the Archbishop of Canterbury. Former provinces New provinces in formation At its Autumn 2020 meeting the provincial standing committee of the Church of Southern Africa approved a plan to form the dioceses in Mozambique and Angola into a separate autonomous province of the Anglican Communion, to be named the Anglican Church of Mozambique and Angola (IAMA). The plans were also outlined to the Mozambique and Angola Anglican Association (MANNA) at its September 2020 annual general meeting. The new province is Portuguese-speaking, and consists of twelve dioceses (four in Angola, and eight in Mozambique). The twelve proposed new dioceses have been defined and named, and each has a "Task Force Committee" working towards its establishment as a diocese. The plan received the consent of the bishops and diocesan synods of all four existing dioceses in the two nations, and was submitted to the Anglican Consultative Council. In September 2020 the Archbishop of Canterbury announced that he had asked the bishops of the Church of Ceylon to begin planning for the formation of an autonomous province of Ceylon, so as to end his current position as Metropolitan of the two dioceses in that country. Churches in full communion In addition to other member churches, the churches of the Anglican Communion are in full communion with the Old Catholic churches of the Union of Utrecht and the Scandinavian Lutheran churches of the Porvoo Communion in Europe, the India-based Malankara Mar Thoma Syrian and Malabar Independent Syrian churches and the Philippine Independent Church, also known as the Aglipayan Church. History The Anglican Communion traces much of its growth to the older mission organisations of the Church of England such as the Society for Promoting Christian Knowledge (founded 1698), the Society for the Propagation of the Gospel in Foreign Parts (founded 1701) and the Church Missionary Society (founded 1799). The Church of England (which until the 20th century included the Church in Wales) initially separated from the Roman Catholic Church in 1534 in the reign of Henry VIII, reunited in 1555 under Mary I and then separated again in 1570 under Elizabeth I (the Roman Catholic Church excommunicated Elizabeth I in 1570 in response to the Act of Supremacy 1559).

In line with the suggestion of the Windsor Report, Rowan Williams (the then Archbishop of Canterbury) established a working group to examine the feasibility of an Anglican covenant which would articulate the conditions for communion in some fashion. Organisation Provinces The Anglican communion consists of forty-one autonomous provinces each with its own primate and governing structure. These provinces may take the form of national churches (such as in Canada, Uganda, or Japan) or a collection of nations (such as the West Indies, Central Africa, or Southeast Asia). Extraprovincial churches In addition to the forty-one provinces, there are five extraprovincial churches under the metropolitical authority of the Archbishop of Canterbury. Former provinces New provinces in formation At its Autumn 2020 meeting the provincial standing committee of the Church of Southern Africa approved a plan to form the dioceses in Mozambique and Angola into a separate autonomous province of the Anglican Communion, to be named the Anglican Church of Mozambique and Angola (IAMA). The plans were also outlined to the Mozambique and Angola Anglican Association (MANNA) at its September 2020 annual general meeting. The new province is Portuguese-speaking, and consists of twelve dioceses (four in Angola, and eight in Mozambique). The twelve proposed new dioceses have been defined and named, and each has a "Task Force Committee" working towards its establishment as a diocese. The plan received the consent of the bishops and diocesan synods of all four existing dioceses in the two nations, and was submitted to the Anglican Consultative Council. In September 2020 the Archbishop of Canterbury announced that he had asked the bishops of the Church of Ceylon to begin planning for the formation of an autonomous province of Ceylon, so as to end his current position as Metropolitan of the two dioceses in that country. Churches in full communion In addition to other member churches, the churches of the Anglican Communion are in full communion with the Old Catholic churches of the Union of Utrecht and the Scandinavian Lutheran churches of the Porvoo Communion in Europe, the India-based Malankara Mar Thoma Syrian and Malabar Independent Syrian churches and the Philippine Independent Church, also known as the Aglipayan Church. History The Anglican Communion traces much of its growth to the older mission organisations of the Church of England such as the Society for Promoting Christian Knowledge (founded 1698), the Society for the Propagation of the Gospel in Foreign Parts (founded 1701) and the Church Missionary Society (founded 1799). The Church of England (which until the 20th century included the Church in Wales) initially separated from the Roman Catholic Church in 1534 in the reign of Henry VIII, reunited in 1555 under Mary I and then separated again in 1570 under Elizabeth I (the Roman Catholic Church excommunicated Elizabeth I in 1570 in response to the Act of Supremacy 1559).

In line with the suggestion of the Windsor Report, Rowan Williams (the then Archbishop of Canterbury) established a working group to examine the feasibility of an Anglican covenant which would articulate the conditions for communion in some fashion. Organisation Provinces The Anglican communion consists of forty-one autonomous provinces each with its own primate and governing structure. These provinces may take the form of national churches (such as in Canada, Uganda, or Japan) or a collection of nations (such as the West Indies, Central Africa, or Southeast Asia). Extraprovincial churches In addition to the forty-one provinces, there are five extraprovincial churches under the metropolitical authority of the Archbishop of Canterbury. Former provinces New provinces in formation At its Autumn 2020 meeting the provincial standing committee of the Church of Southern Africa approved a plan to form the dioceses in Mozambique and Angola into a separate autonomous province of the Anglican Communion, to be named the Anglican Church of Mozambique and Angola (IAMA). The plans were also outlined to the Mozambique and Angola Anglican Association (MANNA) at its September 2020 annual general meeting. The new province is Portuguese-speaking, and consists of twelve dioceses (four in Angola, and eight in Mozambique). The twelve proposed new dioceses have been defined and named, and each has a "Task Force Committee" working towards its establishment as a diocese. The plan received the consent of the bishops and diocesan synods of all four existing dioceses in the two nations, and was submitted to the Anglican Consultative Council. In September 2020 the Archbishop of Canterbury announced that he had asked the bishops of the Church of Ceylon to begin planning for the formation of an autonomous province of Ceylon, so as to end his current position as Metropolitan of the two dioceses in that country. Churches in full communion In addition to other member churches, the churches of the Anglican Communion are in full communion with the Old Catholic churches of the Union of Utrecht and the Scandinavian Lutheran churches of the Porvoo Communion in Europe, the India-based Malankara Mar Thoma Syrian and Malabar Independent Syrian churches and the Philippine Independent Church, also known as the Aglipayan Church. History The Anglican Communion traces much of its growth to the older mission organisations of the Church of England such as the Society for Promoting Christian Knowledge (founded 1698), the Society for the Propagation of the Gospel in Foreign Parts (founded 1701) and the Church Missionary Society (founded 1799). The Church of England (which until the 20th century included the Church in Wales) initially separated from the Roman Catholic Church in 1534 in the reign of Henry VIII, reunited in 1555 under Mary I and then separated again in 1570 under Elizabeth I (the Roman Catholic Church excommunicated Elizabeth I in 1570 in response to the Act of Supremacy 1559).

The Church of England has always thought of itself not as a new foundation but rather as a reformed continuation of the ancient "English Church" (Ecclesia Anglicana) and a reassertion of that church's rights. As such it was a distinctly national phenomenon. The Church of Scotland was formed as a separate church from the Roman Catholic Church as a result of the Scottish Reformation in 1560 and the later formation of the Scottish Episcopal Church began in 1582 in the reign of James VI over disagreements about the role of bishops. The oldest-surviving Anglican church building outside the British Isles (Britain and Ireland) is St Peter's Church in St. George's, Bermuda, established in 1612 (though the actual building had to be rebuilt several times over the following century). This is also the oldest surviving non-Roman Catholic church in the New World. It remained part of the Church of England until 1978 when the Anglican Church of Bermuda separated. The Church of England was the established church not only in England, but in its trans-Oceanic colonies. Thus the only member churches of the present Anglican Communion existing by the mid-18th century were the Church of England, its closely linked sister church the Church of Ireland (which also separated from Roman Catholicism under Henry VIII) and the Scottish Episcopal Church which for parts of the 17th and 18th centuries was partially underground (it was suspected of Jacobite sympathies). Global spread of Anglicanism The enormous expansion in the 18th and 19th centuries of the British Empire brought Anglicanism along with it. At first all these colonial churches were under the jurisdiction of the bishop of London. After the American Revolution, the parishes in the newly independent country found it necessary to break formally from a church whose supreme governor was (and remains) the British monarch. Thus they formed their own dioceses and national church, the Episcopal Church in the United States of America, in a mostly amicable separation. At about the same time, in the colonies which remained linked to the crown, the Church of England began to appoint colonial bishops. In 1787, a bishop of Nova Scotia was appointed with a jurisdiction over all of British North America; in time several more colleagues were appointed to other cities in present-day Canada. In 1814, a bishop of Calcutta was made; in 1824 the first bishop was sent to the West Indies and in 1836 to Australia. By 1840 there were still only ten colonial bishops for the Church of England; but even this small beginning greatly facilitated the growth of Anglicanism around the world. In 1841, a "Colonial Bishoprics Council" was set up and soon many more dioceses were created. In time, it became natural to group these into provinces and a metropolitan bishop was appointed for each province.

The Church of England has always thought of itself not as a new foundation but rather as a reformed continuation of the ancient "English Church" (Ecclesia Anglicana) and a reassertion of that church's rights. As such it was a distinctly national phenomenon. The Church of Scotland was formed as a separate church from the Roman Catholic Church as a result of the Scottish Reformation in 1560 and the later formation of the Scottish Episcopal Church began in 1582 in the reign of James VI over disagreements about the role of bishops. The oldest-surviving Anglican church building outside the British Isles (Britain and Ireland) is St Peter's Church in St. George's, Bermuda, established in 1612 (though the actual building had to be rebuilt several times over the following century). This is also the oldest surviving non-Roman Catholic church in the New World. It remained part of the Church of England until 1978 when the Anglican Church of Bermuda separated. The Church of England was the established church not only in England, but in its trans-Oceanic colonies. Thus the only member churches of the present Anglican Communion existing by the mid-18th century were the Church of England, its closely linked sister church the Church of Ireland (which also separated from Roman Catholicism under Henry VIII) and the Scottish Episcopal Church which for parts of the 17th and 18th centuries was partially underground (it was suspected of Jacobite sympathies). Global spread of Anglicanism The enormous expansion in the 18th and 19th centuries of the British Empire brought Anglicanism along with it. At first all these colonial churches were under the jurisdiction of the bishop of London. After the American Revolution, the parishes in the newly independent country found it necessary to break formally from a church whose supreme governor was (and remains) the British monarch. Thus they formed their own dioceses and national church, the Episcopal Church in the United States of America, in a mostly amicable separation. At about the same time, in the colonies which remained linked to the crown, the Church of England began to appoint colonial bishops. In 1787, a bishop of Nova Scotia was appointed with a jurisdiction over all of British North America; in time several more colleagues were appointed to other cities in present-day Canada. In 1814, a bishop of Calcutta was made; in 1824 the first bishop was sent to the West Indies and in 1836 to Australia. By 1840 there were still only ten colonial bishops for the Church of England; but even this small beginning greatly facilitated the growth of Anglicanism around the world. In 1841, a "Colonial Bishoprics Council" was set up and soon many more dioceses were created. In time, it became natural to group these into provinces and a metropolitan bishop was appointed for each province.

The Church of England has always thought of itself not as a new foundation but rather as a reformed continuation of the ancient "English Church" (Ecclesia Anglicana) and a reassertion of that church's rights. As such it was a distinctly national phenomenon. The Church of Scotland was formed as a separate church from the Roman Catholic Church as a result of the Scottish Reformation in 1560 and the later formation of the Scottish Episcopal Church began in 1582 in the reign of James VI over disagreements about the role of bishops. The oldest-surviving Anglican church building outside the British Isles (Britain and Ireland) is St Peter's Church in St. George's, Bermuda, established in 1612 (though the actual building had to be rebuilt several times over the following century). This is also the oldest surviving non-Roman Catholic church in the New World. It remained part of the Church of England until 1978 when the Anglican Church of Bermuda separated. The Church of England was the established church not only in England, but in its trans-Oceanic colonies. Thus the only member churches of the present Anglican Communion existing by the mid-18th century were the Church of England, its closely linked sister church the Church of Ireland (which also separated from Roman Catholicism under Henry VIII) and the Scottish Episcopal Church which for parts of the 17th and 18th centuries was partially underground (it was suspected of Jacobite sympathies). Global spread of Anglicanism The enormous expansion in the 18th and 19th centuries of the British Empire brought Anglicanism along with it. At first all these colonial churches were under the jurisdiction of the bishop of London. After the American Revolution, the parishes in the newly independent country found it necessary to break formally from a church whose supreme governor was (and remains) the British monarch. Thus they formed their own dioceses and national church, the Episcopal Church in the United States of America, in a mostly amicable separation. At about the same time, in the colonies which remained linked to the crown, the Church of England began to appoint colonial bishops. In 1787, a bishop of Nova Scotia was appointed with a jurisdiction over all of British North America; in time several more colleagues were appointed to other cities in present-day Canada. In 1814, a bishop of Calcutta was made; in 1824 the first bishop was sent to the West Indies and in 1836 to Australia. By 1840 there were still only ten colonial bishops for the Church of England; but even this small beginning greatly facilitated the growth of Anglicanism around the world. In 1841, a "Colonial Bishoprics Council" was set up and soon many more dioceses were created. In time, it became natural to group these into provinces and a metropolitan bishop was appointed for each province.

Although it had at first been somewhat established in many colonies, in 1861 it was ruled that, except where specifically established, the Church of England had just the same legal position as any other church. Thus a colonial bishop and colonial diocese was by nature quite a different thing from their counterparts back home. In time bishops came to be appointed locally rather than from England and eventually national synods began to pass ecclesiastical legislation independent of England. A crucial step in the development of the modern communion was the idea of the Lambeth Conferences (discussed above). These conferences demonstrated that the bishops of disparate churches could manifest the unity of the church in their episcopal collegiality despite the absence of universal legal ties. Some bishops were initially reluctant to attend, fearing that the meeting would declare itself a council with power to legislate for the church; but it agreed to pass only advisory resolutions. These Lambeth Conferences have been held roughly every 10 years since 1878 (the second such conference) and remain the most visible coming-together of the whole Communion. The Lambeth Conference of 1998 included what has been seen by Philip Jenkins and others as a "watershed in global Christianity". The 1998 Lambeth Conference considered the issue of the theology of same-sex attraction in relation to human sexuality. At this 1998 conference for the first time in centuries the Christians of developing regions, especially, Africa, Asia, and Latin America, prevailed over the bishops of more prosperous countries (many from the US, Canada, and the UK) who supported a redefinition of Anglican doctrine. Seen in this light 1998 is a date that marked the shift from a West-dominated Christianity to one wherein the growing churches of the two-thirds world are predominant, but the gay bishop controversy in subsequent years led to the reassertion of Western dominance, this time of the liberal variety. Ecumenical relations Historic episcopate The churches of the Anglican Communion have traditionally held that ordination in the historic episcopate is a core element in the validity of clerical ordinations. The Roman Catholic Church, however, does not recognise Anglican orders (see Apostolicae curae). Some Eastern Orthodox churches have issued statements to the effect that Anglican orders could be accepted, yet have still reordained former Anglican clergy; other Eastern Orthodox churches have rejected Anglican orders altogether. Orthodox bishop Kallistos Ware explains this apparent discrepancy as follows: Controversies One effect of the Communion's dispersed authority has been the conflicts arising over divergent practices and doctrines in parts of the Communion. Disputes that had been confined to the Church of England could be dealt with legislatively in that realm, but as the Communion spread out into new nations and disparate cultures, such controversies multiplied and intensified. These controversies have generally been of two types: liturgical and social. Anglo-Catholicism The first such controversy of note concerned that of the growing influence of the Catholic Revival manifested in the Tractarian and so-called Ritualist controversies of the late nineteenth and early twentieth centuries.

Although it had at first been somewhat established in many colonies, in 1861 it was ruled that, except where specifically established, the Church of England had just the same legal position as any other church. Thus a colonial bishop and colonial diocese was by nature quite a different thing from their counterparts back home. In time bishops came to be appointed locally rather than from England and eventually national synods began to pass ecclesiastical legislation independent of England. A crucial step in the development of the modern communion was the idea of the Lambeth Conferences (discussed above). These conferences demonstrated that the bishops of disparate churches could manifest the unity of the church in their episcopal collegiality despite the absence of universal legal ties. Some bishops were initially reluctant to attend, fearing that the meeting would declare itself a council with power to legislate for the church; but it agreed to pass only advisory resolutions. These Lambeth Conferences have been held roughly every 10 years since 1878 (the second such conference) and remain the most visible coming-together of the whole Communion. The Lambeth Conference of 1998 included what has been seen by Philip Jenkins and others as a "watershed in global Christianity". The 1998 Lambeth Conference considered the issue of the theology of same-sex attraction in relation to human sexuality. At this 1998 conference for the first time in centuries the Christians of developing regions, especially, Africa, Asia, and Latin America, prevailed over the bishops of more prosperous countries (many from the US, Canada, and the UK) who supported a redefinition of Anglican doctrine. Seen in this light 1998 is a date that marked the shift from a West-dominated Christianity to one wherein the growing churches of the two-thirds world are predominant, but the gay bishop controversy in subsequent years led to the reassertion of Western dominance, this time of the liberal variety. Ecumenical relations Historic episcopate The churches of the Anglican Communion have traditionally held that ordination in the historic episcopate is a core element in the validity of clerical ordinations. The Roman Catholic Church, however, does not recognise Anglican orders (see Apostolicae curae). Some Eastern Orthodox churches have issued statements to the effect that Anglican orders could be accepted, yet have still reordained former Anglican clergy; other Eastern Orthodox churches have rejected Anglican orders altogether. Orthodox bishop Kallistos Ware explains this apparent discrepancy as follows: Controversies One effect of the Communion's dispersed authority has been the conflicts arising over divergent practices and doctrines in parts of the Communion. Disputes that had been confined to the Church of England could be dealt with legislatively in that realm, but as the Communion spread out into new nations and disparate cultures, such controversies multiplied and intensified. These controversies have generally been of two types: liturgical and social. Anglo-Catholicism The first such controversy of note concerned that of the growing influence of the Catholic Revival manifested in the Tractarian and so-called Ritualist controversies of the late nineteenth and early twentieth centuries.

Although it had at first been somewhat established in many colonies, in 1861 it was ruled that, except where specifically established, the Church of England had just the same legal position as any other church. Thus a colonial bishop and colonial diocese was by nature quite a different thing from their counterparts back home. In time bishops came to be appointed locally rather than from England and eventually national synods began to pass ecclesiastical legislation independent of England. A crucial step in the development of the modern communion was the idea of the Lambeth Conferences (discussed above). These conferences demonstrated that the bishops of disparate churches could manifest the unity of the church in their episcopal collegiality despite the absence of universal legal ties. Some bishops were initially reluctant to attend, fearing that the meeting would declare itself a council with power to legislate for the church; but it agreed to pass only advisory resolutions. These Lambeth Conferences have been held roughly every 10 years since 1878 (the second such conference) and remain the most visible coming-together of the whole Communion. The Lambeth Conference of 1998 included what has been seen by Philip Jenkins and others as a "watershed in global Christianity". The 1998 Lambeth Conference considered the issue of the theology of same-sex attraction in relation to human sexuality. At this 1998 conference for the first time in centuries the Christians of developing regions, especially, Africa, Asia, and Latin America, prevailed over the bishops of more prosperous countries (many from the US, Canada, and the UK) who supported a redefinition of Anglican doctrine. Seen in this light 1998 is a date that marked the shift from a West-dominated Christianity to one wherein the growing churches of the two-thirds world are predominant, but the gay bishop controversy in subsequent years led to the reassertion of Western dominance, this time of the liberal variety. Ecumenical relations Historic episcopate The churches of the Anglican Communion have traditionally held that ordination in the historic episcopate is a core element in the validity of clerical ordinations. The Roman Catholic Church, however, does not recognise Anglican orders (see Apostolicae curae). Some Eastern Orthodox churches have issued statements to the effect that Anglican orders could be accepted, yet have still reordained former Anglican clergy; other Eastern Orthodox churches have rejected Anglican orders altogether. Orthodox bishop Kallistos Ware explains this apparent discrepancy as follows: Controversies One effect of the Communion's dispersed authority has been the conflicts arising over divergent practices and doctrines in parts of the Communion. Disputes that had been confined to the Church of England could be dealt with legislatively in that realm, but as the Communion spread out into new nations and disparate cultures, such controversies multiplied and intensified. These controversies have generally been of two types: liturgical and social. Anglo-Catholicism The first such controversy of note concerned that of the growing influence of the Catholic Revival manifested in the Tractarian and so-called Ritualist controversies of the late nineteenth and early twentieth centuries.

This controversy produced the Free Church of England and, in the United States and Canada, the Reformed Episcopal Church. Social changes Later, rapid social change and the dissipation of British cultural hegemony over its former colonies contributed to disputes over the role of women, the parameters of marriage and divorce, and the practices of contraception and abortion. In the late 1970s, the Continuing Anglican movement produced a number of new church bodies in opposition to women's ordination, prayer book changes, and the new understandings concerning marriage. Same-sex unions and LGBT clergy More recently, disagreements over homosexuality have strained the unity of the communion as well as its relationships with other Christian denominations, leading to another round of withdrawals from the Anglican Communion. Some churches were founded outside the Anglican Communion in the late 20th and early 21st centuries, largely in opposition to the ordination of openly homosexual bishops and other clergy and are usually referred to as belonging to the Anglican realignment movement, or else as "orthodox" Anglicans. These disagreements were especially noted when the Episcopal Church (US) consecrated an openly gay bishop in a same-sex relationship, Gene Robinson, in 2003, which led some Episcopalians to defect and found the Anglican Church in North America (ACNA); then, the debate re-ignited when the Church of England agreed to allow clergy to enter into same-sex civil partnerships, as long as they remained celibate, in 2005. The Church of Nigeria opposed the Episcopal Church's decision as well as the Church of England's approval for celibate civil partnerships. "The more liberal provinces that are open to changing Church doctrine on marriage in order to allow for same-sex unions include Brazil, Canada, New Zealand, Scotland, South India, South Africa, the US and Wales". The Church of England does not allow same-gender marriages or blessing rites, but does permit special prayer services for same-sex couples following a civil marriage or partnership. The Church of England also permits clergy to enter into same-sex civil partnerships. The Church of Ireland has no official position on civil unions, and one senior cleric has entered into a same-sex civil partnership. The Church of Ireland recognised that it will "treat civil partners the same as spouses". The Anglican Church of Australia does not have an official position on homosexuality. The conservative Anglican churches, encouraging the realignment movement, are more concentrated in the Global South. For example, the Anglican Church of Kenya, the Church of Nigeria and the Church of Uganda have opposed homosexuality. GAFCON, a fellowship of conservative Anglican churches, has appointed "missionary bishops" in response to the disagreements with the perceived liberalisation in the Anglican churches in North America and Europe. Debates about social theology and ethics have occurred at the same time as debates on prayer book revision and the acceptable grounds for achieving full communion with non-Anglican churches.

This controversy produced the Free Church of England and, in the United States and Canada, the Reformed Episcopal Church. Social changes Later, rapid social change and the dissipation of British cultural hegemony over its former colonies contributed to disputes over the role of women, the parameters of marriage and divorce, and the practices of contraception and abortion. In the late 1970s, the Continuing Anglican movement produced a number of new church bodies in opposition to women's ordination, prayer book changes, and the new understandings concerning marriage. Same-sex unions and LGBT clergy More recently, disagreements over homosexuality have strained the unity of the communion as well as its relationships with other Christian denominations, leading to another round of withdrawals from the Anglican Communion. Some churches were founded outside the Anglican Communion in the late 20th and early 21st centuries, largely in opposition to the ordination of openly homosexual bishops and other clergy and are usually referred to as belonging to the Anglican realignment movement, or else as "orthodox" Anglicans. These disagreements were especially noted when the Episcopal Church (US) consecrated an openly gay bishop in a same-sex relationship, Gene Robinson, in 2003, which led some Episcopalians to defect and found the Anglican Church in North America (ACNA); then, the debate re-ignited when the Church of England agreed to allow clergy to enter into same-sex civil partnerships, as long as they remained celibate, in 2005. The Church of Nigeria opposed the Episcopal Church's decision as well as the Church of England's approval for celibate civil partnerships. "The more liberal provinces that are open to changing Church doctrine on marriage in order to allow for same-sex unions include Brazil, Canada, New Zealand, Scotland, South India, South Africa, the US and Wales". The Church of England does not allow same-gender marriages or blessing rites, but does permit special prayer services for same-sex couples following a civil marriage or partnership. The Church of England also permits clergy to enter into same-sex civil partnerships. The Church of Ireland has no official position on civil unions, and one senior cleric has entered into a same-sex civil partnership. The Church of Ireland recognised that it will "treat civil partners the same as spouses". The Anglican Church of Australia does not have an official position on homosexuality. The conservative Anglican churches, encouraging the realignment movement, are more concentrated in the Global South. For example, the Anglican Church of Kenya, the Church of Nigeria and the Church of Uganda have opposed homosexuality. GAFCON, a fellowship of conservative Anglican churches, has appointed "missionary bishops" in response to the disagreements with the perceived liberalisation in the Anglican churches in North America and Europe. Debates about social theology and ethics have occurred at the same time as debates on prayer book revision and the acceptable grounds for achieving full communion with non-Anglican churches.

This controversy produced the Free Church of England and, in the United States and Canada, the Reformed Episcopal Church. Social changes Later, rapid social change and the dissipation of British cultural hegemony over its former colonies contributed to disputes over the role of women, the parameters of marriage and divorce, and the practices of contraception and abortion. In the late 1970s, the Continuing Anglican movement produced a number of new church bodies in opposition to women's ordination, prayer book changes, and the new understandings concerning marriage. Same-sex unions and LGBT clergy More recently, disagreements over homosexuality have strained the unity of the communion as well as its relationships with other Christian denominations, leading to another round of withdrawals from the Anglican Communion. Some churches were founded outside the Anglican Communion in the late 20th and early 21st centuries, largely in opposition to the ordination of openly homosexual bishops and other clergy and are usually referred to as belonging to the Anglican realignment movement, or else as "orthodox" Anglicans. These disagreements were especially noted when the Episcopal Church (US) consecrated an openly gay bishop in a same-sex relationship, Gene Robinson, in 2003, which led some Episcopalians to defect and found the Anglican Church in North America (ACNA); then, the debate re-ignited when the Church of England agreed to allow clergy to enter into same-sex civil partnerships, as long as they remained celibate, in 2005. The Church of Nigeria opposed the Episcopal Church's decision as well as the Church of England's approval for celibate civil partnerships. "The more liberal provinces that are open to changing Church doctrine on marriage in order to allow for same-sex unions include Brazil, Canada, New Zealand, Scotland, South India, South Africa, the US and Wales". The Church of England does not allow same-gender marriages or blessing rites, but does permit special prayer services for same-sex couples following a civil marriage or partnership. The Church of England also permits clergy to enter into same-sex civil partnerships. The Church of Ireland has no official position on civil unions, and one senior cleric has entered into a same-sex civil partnership. The Church of Ireland recognised that it will "treat civil partners the same as spouses". The Anglican Church of Australia does not have an official position on homosexuality. The conservative Anglican churches, encouraging the realignment movement, are more concentrated in the Global South. For example, the Anglican Church of Kenya, the Church of Nigeria and the Church of Uganda have opposed homosexuality. GAFCON, a fellowship of conservative Anglican churches, has appointed "missionary bishops" in response to the disagreements with the perceived liberalisation in the Anglican churches in North America and Europe. Debates about social theology and ethics have occurred at the same time as debates on prayer book revision and the acceptable grounds for achieving full communion with non-Anglican churches.

See also Acts of Supremacy English Reformation Dissolution of the Monasteries Ritualism in the Church of England Apostolicae curae Affirming Catholicism Anglican ministry Anglo-Catholicism British Israelism Church Society Church's Ministry Among Jewish People Compass rose Evangelical Anglicanism Flag of the Anglican Communion Liberal Anglo-Catholicism List of conservative evangelical Anglican churches in England List of heroes of the Christian Church in the Anglican Communion List of the largest Protestant bodies Reform (Anglican) Anglican Use Notes References Citations Sources Further reading Buchanan, Colin. Historical Dictionary of Anglicanism (2nd ed. 2015) excerpt Hebert, A. G. The Form of the Church. London: Faber and Faber, 1944. Wild, John. What is the Anglican Communion?, in series, The Advent Papers. Cincinnati, Ohio: Forward Movement Publications, [196-]. Note. : Expresses the "Anglo-Catholic" viewpoint. External links Anglicans Online Project Canterbury Anglican historical documents from around the world Brief description and history of the Anglican Communion 1997 article from the Anglican Communion Office 1867 establishments in England Religious organizations established in 1867 Religion in the British Empire

See also Acts of Supremacy English Reformation Dissolution of the Monasteries Ritualism in the Church of England Apostolicae curae Affirming Catholicism Anglican ministry Anglo-Catholicism British Israelism Church Society Church's Ministry Among Jewish People Compass rose Evangelical Anglicanism Flag of the Anglican Communion Liberal Anglo-Catholicism List of conservative evangelical Anglican churches in England List of heroes of the Christian Church in the Anglican Communion List of the largest Protestant bodies Reform (Anglican) Anglican Use Notes References Citations Sources Further reading Buchanan, Colin. Historical Dictionary of Anglicanism (2nd ed. 2015) excerpt Hebert, A. G. The Form of the Church. London: Faber and Faber, 1944. Wild, John. What is the Anglican Communion?, in series, The Advent Papers. Cincinnati, Ohio: Forward Movement Publications, [196-]. Note. : Expresses the "Anglo-Catholic" viewpoint. External links Anglicans Online Project Canterbury Anglican historical documents from around the world Brief description and history of the Anglican Communion 1997 article from the Anglican Communion Office 1867 establishments in England Religious organizations established in 1867 Religion in the British Empire

See also Acts of Supremacy English Reformation Dissolution of the Monasteries Ritualism in the Church of England Apostolicae curae Affirming Catholicism Anglican ministry Anglo-Catholicism British Israelism Church Society Church's Ministry Among Jewish People Compass rose Evangelical Anglicanism Flag of the Anglican Communion Liberal Anglo-Catholicism List of conservative evangelical Anglican churches in England List of heroes of the Christian Church in the Anglican Communion List of the largest Protestant bodies Reform (Anglican) Anglican Use Notes References Citations Sources Further reading Buchanan, Colin. Historical Dictionary of Anglicanism (2nd ed. 2015) excerpt Hebert, A. G. The Form of the Church. London: Faber and Faber, 1944. Wild, John. What is the Anglican Communion?, in series, The Advent Papers. Cincinnati, Ohio: Forward Movement Publications, [196-]. Note. : Expresses the "Anglo-Catholic" viewpoint. External links Anglicans Online Project Canterbury Anglican historical documents from around the world Brief description and history of the Anglican Communion 1997 article from the Anglican Communion Office 1867 establishments in England Religious organizations established in 1867 Religion in the British Empire

Arne Kaijser Arne Kaijser (born 1950) is a professor emeritus of history of technology at the KTH Royal Institute of Technology in Stockholm, and a former president of the Society for the History of Technology. Kaijser has published two books in Swedish: Stadens ljus. Etableringen av de första svenska gasverken and I fädrens spår. Den svenska infrastrukturens historiska utveckling och framtida utmaningar, and has co-edited several anthologies. Kaijser is a member of the Royal Swedish Academy of Engineering Sciences since 2007 and also a member of the editorial board of two scientific journals: Journal of Urban Technology and Centaurus. Lately, he has been occupied with the history of Large Technical Systems. References External links Homepage Extended homepage 1950 births Living people Swedish historians KTH Royal Institute of Technology faculty Members of the Royal Swedish Academy of Engineering Sciences Historians of science Historians of technology Linköping University alumni

Arne Kaijser Arne Kaijser (born 1950) is a professor emeritus of history of technology at the KTH Royal Institute of Technology in Stockholm, and a former president of the Society for the History of Technology. Kaijser has published two books in Swedish: Stadens ljus. Etableringen av de första svenska gasverken and I fädrens spår. Den svenska infrastrukturens historiska utveckling och framtida utmaningar, and has co-edited several anthologies. Kaijser is a member of the Royal Swedish Academy of Engineering Sciences since 2007 and also a member of the editorial board of two scientific journals: Journal of Urban Technology and Centaurus. Lately, he has been occupied with the history of Large Technical Systems. References External links Homepage Extended homepage 1950 births Living people Swedish historians KTH Royal Institute of Technology faculty Members of the Royal Swedish Academy of Engineering Sciences Historians of science Historians of technology Linköping University alumni

Archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Archipelago, the Andaman and Nicobar Islands, the Lakshadweep Islands, the Galápagos Islands, the Japanese Archipelago, the Philippine Archipelago, the Maldives, the Balearic Isles, the Bahamas, the Aegean Islands, the Hawaiian Islands, the Canary Islands, Malta, the Azores, the Canadian Arctic Archipelago, the British Isles, the islands of the Archipelago Sea, and Shetland. They are sometimes defined by political boundaries. The Gulf archipelago off the north-eastern Pacific coast forms part of a larger archipelago that geographically includes Washington state's San Juan Islands. While the Gulf archipelago and San Juan Islands are geographically related, they are not technically included in the same archipelago due to manmade geopolitical borders. Etymology The word archipelago is derived from the Ancient Greek ἄρχι-(arkhi-, "chief") and πέλαγος (pélagos, "sea") through the Italian arcipelago. In antiquity, "Archipelago" (from medieval Greek *ἀρχιπέλαγος and Latin ) was the proper name for the Aegean Sea. Later, usage shifted to refer to the Aegean Islands (since the sea has a large number of islands). Geographic types Archipelagos may be found isolated in large amounts of water or neighbouring a large land mass. For example, Scotland has more than 700 islands surrounding its mainland which form an archipelago. Archipelagos are often volcanic, forming along island arcs generated by subduction zones or hotspots, but may also be the result of erosion, deposition, and land elevation. Depending on their geological origin, islands forming archipelagos can be referred to as oceanic islands, continental fragments, and continental islands. Oceanic islands Oceanic islands are mainly of volcanic origin, and widely separated from any adjacent continent. The Hawaiian Islands and Easter Island in the Pacific, and Île Amsterdam in the south Indian Ocean are examples. Continental fragments Continental fragments correspond to land masses that have separated from a continental mass due to tectonic displacement. The Farallon Islands off the coast of California are an example. Continental archipelagos Sets of islands formed close to the coast of a continent are considered continental archipelagos when they form part of the same continental shelf, when those islands are above-water extensions of the shelf. The islands of the Inside Passage off the coast of British Columbia and the Canadian Arctic Archipelago are examples. Artificial archipelagos Artificial archipelagos have been created in various countries for different purposes. Palm Islands and the World Islands off Dubai were or are being created for leisure and tourism purposes. Marker Wadden in the Netherlands is being built as a conservation area for birds and other wildlife. Further examples The largest archipelagic state in the world by area, and by population, is Indonesia. See also Island arc List of landforms List of archipelagos by number of islands List of archipelagos Archipelagic state List of islands Aquapelago References External links 30 Most Incredible Island Archipelagos Coastal and oceanic landforms Oceanographical terminology

Archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Archipelago, the Andaman and Nicobar Islands, the Lakshadweep Islands, the Galápagos Islands, the Japanese Archipelago, the Philippine Archipelago, the Maldives, the Balearic Isles, the Bahamas, the Aegean Islands, the Hawaiian Islands, the Canary Islands, Malta, the Azores, the Canadian Arctic Archipelago, the British Isles, the islands of the Archipelago Sea, and Shetland. They are sometimes defined by political boundaries. The Gulf archipelago off the north-eastern Pacific coast forms part of a larger archipelago that geographically includes Washington state's San Juan Islands. While the Gulf archipelago and San Juan Islands are geographically related, they are not technically included in the same archipelago due to manmade geopolitical borders. Etymology The word archipelago is derived from the Ancient Greek ἄρχι-(arkhi-, "chief") and πέλαγος (pélagos, "sea") through the Italian arcipelago. In antiquity, "Archipelago" (from medieval Greek *ἀρχιπέλαγος and Latin ) was the proper name for the Aegean Sea. Later, usage shifted to refer to the Aegean Islands (since the sea has a large number of islands). Geographic types Archipelagos may be found isolated in large amounts of water or neighbouring a large land mass. For example, Scotland has more than 700 islands surrounding its mainland which form an archipelago. Archipelagos are often volcanic, forming along island arcs generated by subduction zones or hotspots, but may also be the result of erosion, deposition, and land elevation. Depending on their geological origin, islands forming archipelagos can be referred to as oceanic islands, continental fragments, and continental islands. Oceanic islands Oceanic islands are mainly of volcanic origin, and widely separated from any adjacent continent. The Hawaiian Islands and Easter Island in the Pacific, and Île Amsterdam in the south Indian Ocean are examples. Continental fragments Continental fragments correspond to land masses that have separated from a continental mass due to tectonic displacement. The Farallon Islands off the coast of California are an example. Continental archipelagos Sets of islands formed close to the coast of a continent are considered continental archipelagos when they form part of the same continental shelf, when those islands are above-water extensions of the shelf. The islands of the Inside Passage off the coast of British Columbia and the Canadian Arctic Archipelago are examples. Artificial archipelagos Artificial archipelagos have been created in various countries for different purposes. Palm Islands and the World Islands off Dubai were or are being created for leisure and tourism purposes. Marker Wadden in the Netherlands is being built as a conservation area for birds and other wildlife. Further examples The largest archipelagic state in the world by area, and by population, is Indonesia. See also Island arc List of landforms List of archipelagos by number of islands List of archipelagos Archipelagic state List of islands Aquapelago References External links 30 Most Incredible Island Archipelagos Coastal and oceanic landforms Oceanographical terminology

Author An author is the creator or originator of any written work such as a book or play, and is also considered a writer or poet. More broadly defined, an author is "the person who originated or gave existence to anything" and whose authorship determines responsibility for what was created. Legal significance of authorship Typically, the first owner of a copyright is the person who created the work, i.e. the author. If more than one person created the work, then a case of joint authorship can be made provided some criteria are met. In the copyright laws of various jurisdictions, there is a necessity for little flexibility regarding what constitutes authorship. The United States Copyright Office, for example, defines copyright as "a form of protection provided by the laws of the United States (title 17, U.S. Code) to authors of 'original works of authorship.'" Holding the title of "author" over any "literary, dramatic, musical, artistic, [or] certain other intellectual works" gives rights to this person, the owner of the copyright, especially the exclusive right to engage in or authorize any production or distribution of their work. Any person or entity wishing to use intellectual property held under copyright must receive permission from the copyright holder to use this work, and often will be asked to pay for the use of copyrighted material. After a fixed amount of time, the copyright expires on intellectual work and it enters the public domain, where it can be used without limit. Copyright laws in many jurisdictions – mostly following the lead of the United States, in which the entertainment and publishing industries have very strong lobbying power – have been amended repeatedly since their inception, to extend the length of this fixed period where the work is exclusively controlled by the copyright holder. However, copyright is merely the legal reassurance that one owns their work. Technically, someone owns their work from the time it's created. A notable aspect of authorship emerges with copyright in that, in many jurisdictions, it can be passed down to another upon one's death. The person who inherits the copyright is not the author, but enjoys the same legal benefits. Questions arise as to the application of copyright law. How does it, for example, apply to the complex issue of fan fiction? If the media agency responsible for the authorized production allows material from fans, what is the limit before legal constraints from actors, music, and other considerations, come into play? Additionally, how does copyright apply to fan-generated stories for books? What powers do the original authors, as well as the publishers, have in regulating or even stopping the fan fiction? This particular sort of case also illustrates how complex intellectual property law can be, since such fiction may also involved trademark law (e.g.

Author An author is the creator or originator of any written work such as a book or play, and is also considered a writer or poet. More broadly defined, an author is "the person who originated or gave existence to anything" and whose authorship determines responsibility for what was created. Legal significance of authorship Typically, the first owner of a copyright is the person who created the work, i.e. the author. If more than one person created the work, then a case of joint authorship can be made provided some criteria are met. In the copyright laws of various jurisdictions, there is a necessity for little flexibility regarding what constitutes authorship. The United States Copyright Office, for example, defines copyright as "a form of protection provided by the laws of the United States (title 17, U.S. Code) to authors of 'original works of authorship.'" Holding the title of "author" over any "literary, dramatic, musical, artistic, [or] certain other intellectual works" gives rights to this person, the owner of the copyright, especially the exclusive right to engage in or authorize any production or distribution of their work. Any person or entity wishing to use intellectual property held under copyright must receive permission from the copyright holder to use this work, and often will be asked to pay for the use of copyrighted material. After a fixed amount of time, the copyright expires on intellectual work and it enters the public domain, where it can be used without limit. Copyright laws in many jurisdictions – mostly following the lead of the United States, in which the entertainment and publishing industries have very strong lobbying power – have been amended repeatedly since their inception, to extend the length of this fixed period where the work is exclusively controlled by the copyright holder. However, copyright is merely the legal reassurance that one owns their work. Technically, someone owns their work from the time it's created. A notable aspect of authorship emerges with copyright in that, in many jurisdictions, it can be passed down to another upon one's death. The person who inherits the copyright is not the author, but enjoys the same legal benefits. Questions arise as to the application of copyright law. How does it, for example, apply to the complex issue of fan fiction? If the media agency responsible for the authorized production allows material from fans, what is the limit before legal constraints from actors, music, and other considerations, come into play? Additionally, how does copyright apply to fan-generated stories for books? What powers do the original authors, as well as the publishers, have in regulating or even stopping the fan fiction? This particular sort of case also illustrates how complex intellectual property law can be, since such fiction may also involved trademark law (e.g.

for names of characters in media franchises), likeness rights (such as for actors, or even entirely fictional entities), fair use rights held by the public (including the right to parody or satirize), and many other interacting complications. Authors may portion out different rights they hold to different parties, at different times, and for different purposes or uses, such as the right to adapt a plot into a film, but only with different character names, because the characters have already been optioned by another company for a television series or a video game. An author may also not have rights when working under contract that they would otherwise have, such as when creating a work for hire (e.g., hired to write a city tour guide by a municipal government that totally owns the copyright to the finished work), or when writing material using intellectual property owned by others (such as when writing a novel or screenplay that is a new installment in an already established media franchise). Philosophical views of the nature of authorship In literary theory, critics find complications in the term author beyond what constitutes authorship in a legal setting. In the wake of postmodern literature, critics such as Roland Barthes and Michel Foucault have examined the role and relevance of authorship to the meaning or interpretation of a text. Barthes challenges the idea that a text can be attributed to any single author. He writes, in his essay "Death of the Author" (1968), that "it is language which speaks, not the author." The words and language of a text itself determine and expose meaning for Barthes, and not someone possessing legal responsibility for the process of its production. Every line of written text is a mere reflection of references from any of a multitude of traditions, or, as Barthes puts it, "the text is a tissue of quotations drawn from the innumerable centres of culture"; it is never original. With this, the perspective of the author is removed from the text, and the limits formerly imposed by the idea of one authorial voice, one ultimate and universal meaning, are destroyed. The explanation and meaning of a work does not have to be sought in the one who produced it, "as if it were always in the end, through the more or less transparent allegory of the fiction, the voice of a single person, the author 'confiding' in us." The psyche, culture, fanaticism of an author can be disregarded when interpreting a text, because the words are rich enough themselves with all of the traditions of language. To expose meanings in a written work without appealing to the celebrity of an author, their tastes, passions, vices, is, to Barthes, to allow language to speak, rather than author. Michel Foucault argues in his essay "What is an author?" (1969) that all authors are writers, but not all writers are authors. He states that "a private letter may have a signatory—it does not have an author."

for names of characters in media franchises), likeness rights (such as for actors, or even entirely fictional entities), fair use rights held by the public (including the right to parody or satirize), and many other interacting complications. Authors may portion out different rights they hold to different parties, at different times, and for different purposes or uses, such as the right to adapt a plot into a film, but only with different character names, because the characters have already been optioned by another company for a television series or a video game. An author may also not have rights when working under contract that they would otherwise have, such as when creating a work for hire (e.g., hired to write a city tour guide by a municipal government that totally owns the copyright to the finished work), or when writing material using intellectual property owned by others (such as when writing a novel or screenplay that is a new installment in an already established media franchise). Philosophical views of the nature of authorship In literary theory, critics find complications in the term author beyond what constitutes authorship in a legal setting. In the wake of postmodern literature, critics such as Roland Barthes and Michel Foucault have examined the role and relevance of authorship to the meaning or interpretation of a text. Barthes challenges the idea that a text can be attributed to any single author. He writes, in his essay "Death of the Author" (1968), that "it is language which speaks, not the author." The words and language of a text itself determine and expose meaning for Barthes, and not someone possessing legal responsibility for the process of its production. Every line of written text is a mere reflection of references from any of a multitude of traditions, or, as Barthes puts it, "the text is a tissue of quotations drawn from the innumerable centres of culture"; it is never original. With this, the perspective of the author is removed from the text, and the limits formerly imposed by the idea of one authorial voice, one ultimate and universal meaning, are destroyed. The explanation and meaning of a work does not have to be sought in the one who produced it, "as if it were always in the end, through the more or less transparent allegory of the fiction, the voice of a single person, the author 'confiding' in us." The psyche, culture, fanaticism of an author can be disregarded when interpreting a text, because the words are rich enough themselves with all of the traditions of language. To expose meanings in a written work without appealing to the celebrity of an author, their tastes, passions, vices, is, to Barthes, to allow language to speak, rather than author. Michel Foucault argues in his essay "What is an author?" (1969) that all authors are writers, but not all writers are authors. He states that "a private letter may have a signatory—it does not have an author."

for names of characters in media franchises), likeness rights (such as for actors, or even entirely fictional entities), fair use rights held by the public (including the right to parody or satirize), and many other interacting complications. Authors may portion out different rights they hold to different parties, at different times, and for different purposes or uses, such as the right to adapt a plot into a film, but only with different character names, because the characters have already been optioned by another company for a television series or a video game. An author may also not have rights when working under contract that they would otherwise have, such as when creating a work for hire (e.g., hired to write a city tour guide by a municipal government that totally owns the copyright to the finished work), or when writing material using intellectual property owned by others (such as when writing a novel or screenplay that is a new installment in an already established media franchise). Philosophical views of the nature of authorship In literary theory, critics find complications in the term author beyond what constitutes authorship in a legal setting. In the wake of postmodern literature, critics such as Roland Barthes and Michel Foucault have examined the role and relevance of authorship to the meaning or interpretation of a text. Barthes challenges the idea that a text can be attributed to any single author. He writes, in his essay "Death of the Author" (1968), that "it is language which speaks, not the author." The words and language of a text itself determine and expose meaning for Barthes, and not someone possessing legal responsibility for the process of its production. Every line of written text is a mere reflection of references from any of a multitude of traditions, or, as Barthes puts it, "the text is a tissue of quotations drawn from the innumerable centres of culture"; it is never original. With this, the perspective of the author is removed from the text, and the limits formerly imposed by the idea of one authorial voice, one ultimate and universal meaning, are destroyed. The explanation and meaning of a work does not have to be sought in the one who produced it, "as if it were always in the end, through the more or less transparent allegory of the fiction, the voice of a single person, the author 'confiding' in us." The psyche, culture, fanaticism of an author can be disregarded when interpreting a text, because the words are rich enough themselves with all of the traditions of language. To expose meanings in a written work without appealing to the celebrity of an author, their tastes, passions, vices, is, to Barthes, to allow language to speak, rather than author. Michel Foucault argues in his essay "What is an author?" (1969) that all authors are writers, but not all writers are authors. He states that "a private letter may have a signatory—it does not have an author."

For a reader to assign the title of author upon any written work is to attribute certain standards upon the text which, for Foucault, are working in conjunction with the idea of "the author function." Foucault's author function is the idea that an author exists only as a function of a written work, a part of its structure, but not necessarily part of the interpretive process. The author's name "indicates the status of the discourse within a society and culture," and at one time was used as an anchor for interpreting a text, a practice which Barthes would argue is not a particularly relevant or valid endeavour. Expanding upon Foucault's position, Alexander Nehamas writes that Foucault suggests "an author [...] is whoever can be understood to have produced a particular text as we interpret it," not necessarily who penned the text. It is this distinction between producing a written work and producing the interpretation or meaning in a written work that both Barthes and Foucault are interested in. Foucault warns of the risks of keeping the author's name in mind during interpretation, because it could affect the value and meaning with which one handles an interpretation. Literary critics Barthes and Foucault suggest that readers should not rely on or look for the notion of one overarching voice when interpreting a written work, because of the complications inherent with a writer's title of "author." They warn of the dangers interpretations could suffer from when associating the subject of inherently meaningful words and language with the personality of one authorial voice. Instead, readers should allow a text to be interpreted in terms of the language as "author." Relationship with publisher Self-publishing Self-publishing, self-publishing, independent publishing, or artisanal publishing is the "publication of any book, album or other media by its author without the involvement of a traditional publisher. It is the modern equivalent to traditional publishing." Types Unless a book is to be sold directly from the author to the public, an ISBN is required to uniquely identify the title. ISBN is a global standard used for all titles worldwide. Most self-publishing companies either provide their own ISBN to a title or can provide direction; it may be in the best interest of the self-published author to retain ownership of ISBN and copyright instead of using a number owned by a vanity press. A separate ISBN is needed for each edition of the book. Electronic (e-book) publishing There are a variety of book formats and tools that can be used to create them. Because it is possible to create e-books with no up-front or per-book costs, this is a popular option for self-publishers. E-book publishing platforms include Pronoun, Smashwords, Blurb, Amazon Kindle Direct Publishing, CinnamonTeal Publishing, Papyrus Editor, ebook leap, Bookbaby, Pubit, Lulu, Llumina Press, and CreateSpace. E-book formats include epub, mobi, and PDF, among others. Print-on-demand Print-on-demand (POD) publishing refers to the ability to print high-quality books as needed.

For a reader to assign the title of author upon any written work is to attribute certain standards upon the text which, for Foucault, are working in conjunction with the idea of "the author function." Foucault's author function is the idea that an author exists only as a function of a written work, a part of its structure, but not necessarily part of the interpretive process. The author's name "indicates the status of the discourse within a society and culture," and at one time was used as an anchor for interpreting a text, a practice which Barthes would argue is not a particularly relevant or valid endeavour. Expanding upon Foucault's position, Alexander Nehamas writes that Foucault suggests "an author [...] is whoever can be understood to have produced a particular text as we interpret it," not necessarily who penned the text. It is this distinction between producing a written work and producing the interpretation or meaning in a written work that both Barthes and Foucault are interested in. Foucault warns of the risks of keeping the author's name in mind during interpretation, because it could affect the value and meaning with which one handles an interpretation. Literary critics Barthes and Foucault suggest that readers should not rely on or look for the notion of one overarching voice when interpreting a written work, because of the complications inherent with a writer's title of "author." They warn of the dangers interpretations could suffer from when associating the subject of inherently meaningful words and language with the personality of one authorial voice. Instead, readers should allow a text to be interpreted in terms of the language as "author." Relationship with publisher Self-publishing Self-publishing, self-publishing, independent publishing, or artisanal publishing is the "publication of any book, album or other media by its author without the involvement of a traditional publisher. It is the modern equivalent to traditional publishing." Types Unless a book is to be sold directly from the author to the public, an ISBN is required to uniquely identify the title. ISBN is a global standard used for all titles worldwide. Most self-publishing companies either provide their own ISBN to a title or can provide direction; it may be in the best interest of the self-published author to retain ownership of ISBN and copyright instead of using a number owned by a vanity press. A separate ISBN is needed for each edition of the book. Electronic (e-book) publishing There are a variety of book formats and tools that can be used to create them. Because it is possible to create e-books with no up-front or per-book costs, this is a popular option for self-publishers. E-book publishing platforms include Pronoun, Smashwords, Blurb, Amazon Kindle Direct Publishing, CinnamonTeal Publishing, Papyrus Editor, ebook leap, Bookbaby, Pubit, Lulu, Llumina Press, and CreateSpace. E-book formats include epub, mobi, and PDF, among others. Print-on-demand Print-on-demand (POD) publishing refers to the ability to print high-quality books as needed.

For a reader to assign the title of author upon any written work is to attribute certain standards upon the text which, for Foucault, are working in conjunction with the idea of "the author function." Foucault's author function is the idea that an author exists only as a function of a written work, a part of its structure, but not necessarily part of the interpretive process. The author's name "indicates the status of the discourse within a society and culture," and at one time was used as an anchor for interpreting a text, a practice which Barthes would argue is not a particularly relevant or valid endeavour. Expanding upon Foucault's position, Alexander Nehamas writes that Foucault suggests "an author [...] is whoever can be understood to have produced a particular text as we interpret it," not necessarily who penned the text. It is this distinction between producing a written work and producing the interpretation or meaning in a written work that both Barthes and Foucault are interested in. Foucault warns of the risks of keeping the author's name in mind during interpretation, because it could affect the value and meaning with which one handles an interpretation. Literary critics Barthes and Foucault suggest that readers should not rely on or look for the notion of one overarching voice when interpreting a written work, because of the complications inherent with a writer's title of "author." They warn of the dangers interpretations could suffer from when associating the subject of inherently meaningful words and language with the personality of one authorial voice. Instead, readers should allow a text to be interpreted in terms of the language as "author." Relationship with publisher Self-publishing Self-publishing, self-publishing, independent publishing, or artisanal publishing is the "publication of any book, album or other media by its author without the involvement of a traditional publisher. It is the modern equivalent to traditional publishing." Types Unless a book is to be sold directly from the author to the public, an ISBN is required to uniquely identify the title. ISBN is a global standard used for all titles worldwide. Most self-publishing companies either provide their own ISBN to a title or can provide direction; it may be in the best interest of the self-published author to retain ownership of ISBN and copyright instead of using a number owned by a vanity press. A separate ISBN is needed for each edition of the book. Electronic (e-book) publishing There are a variety of book formats and tools that can be used to create them. Because it is possible to create e-books with no up-front or per-book costs, this is a popular option for self-publishers. E-book publishing platforms include Pronoun, Smashwords, Blurb, Amazon Kindle Direct Publishing, CinnamonTeal Publishing, Papyrus Editor, ebook leap, Bookbaby, Pubit, Lulu, Llumina Press, and CreateSpace. E-book formats include epub, mobi, and PDF, among others. Print-on-demand Print-on-demand (POD) publishing refers to the ability to print high-quality books as needed.

For self-published books, this is often a more economical option than conducting a print run of hundreds or thousands of books. Many companies, such as Createspace (owned by Amazon.com), Outskirts Press, Blurb, Lulu, Llumina Press, ReadersMagnet, and iUniverse, allow printing single books at per-book costs not much higher than those paid by publishing companies for large print runs. Traditional publishing With commissioned publishing, the publisher makes all the publication arrangements and the author covers all expenses. The author of a work may receive a percentage calculated on a wholesale or a specific price or a fixed amount on each book sold. Publishers, at times, reduced the risk of this type of arrangement, by agreeing only to pay this after a certain number of copies had sold. In Canada, this practice occurred during the 1890s, but was not commonplace until the 1920s. Established and successful authors may receive advance payments, set against future royalties, but this is no longer common practice. Most independent publishers pay royalties as a percentage of net receipts – how net receipts are calculated varies from publisher to publisher. Under this arrangement, the author does not pay anything towards the expense of publication. The costs and financial risk are all carried by the publisher, who will then take the greatest percentage of the receipts. See Compensation for more. Vanity publishing This type of publisher normally charges a flat fee for arranging publication, offers a platform for selling, and then takes a percentage of the sale of every copy of a book. The author receives the rest of the money made. Relationship with editor The relationship between the author and the editor, often the author's only liaison to the publishing company, is often characterized as the site of tension. For the author to reach their audience, often through publication, the work usually must attract the attention of the editor. The idea of the author as the sole meaning-maker of necessity changes to include the influences of the editor and the publisher in order to engage the audience in writing as a social act. There are three principal areas covered by editors – Proofing (checking the Grammar and spelling, looking for typing errors), Story (potentially an area of deep angst for both author and publisher), and Layout (the setting of the final proof ready for publishing often requires minor text changes so a layout editor is required to ensure that these do not alter the sense of the text). Pierre Bourdieu's essay "The Field of Cultural Production" depicts the publishing industry as a "space of literary or artistic position-takings," also called the "field of struggles," which is defined by the tension and movement inherent among the various positions in the field. Bourdieu claims that the "field of position-takings [...] is not the product of coherence-seeking intention or objective consensus," meaning that an industry characterized by position-takings is not one of harmony and neutrality.

For self-published books, this is often a more economical option than conducting a print run of hundreds or thousands of books. Many companies, such as Createspace (owned by Amazon.com), Outskirts Press, Blurb, Lulu, Llumina Press, ReadersMagnet, and iUniverse, allow printing single books at per-book costs not much higher than those paid by publishing companies for large print runs. Traditional publishing With commissioned publishing, the publisher makes all the publication arrangements and the author covers all expenses. The author of a work may receive a percentage calculated on a wholesale or a specific price or a fixed amount on each book sold. Publishers, at times, reduced the risk of this type of arrangement, by agreeing only to pay this after a certain number of copies had sold. In Canada, this practice occurred during the 1890s, but was not commonplace until the 1920s. Established and successful authors may receive advance payments, set against future royalties, but this is no longer common practice. Most independent publishers pay royalties as a percentage of net receipts – how net receipts are calculated varies from publisher to publisher. Under this arrangement, the author does not pay anything towards the expense of publication. The costs and financial risk are all carried by the publisher, who will then take the greatest percentage of the receipts. See Compensation for more. Vanity publishing This type of publisher normally charges a flat fee for arranging publication, offers a platform for selling, and then takes a percentage of the sale of every copy of a book. The author receives the rest of the money made. Relationship with editor The relationship between the author and the editor, often the author's only liaison to the publishing company, is often characterized as the site of tension. For the author to reach their audience, often through publication, the work usually must attract the attention of the editor. The idea of the author as the sole meaning-maker of necessity changes to include the influences of the editor and the publisher in order to engage the audience in writing as a social act. There are three principal areas covered by editors – Proofing (checking the Grammar and spelling, looking for typing errors), Story (potentially an area of deep angst for both author and publisher), and Layout (the setting of the final proof ready for publishing often requires minor text changes so a layout editor is required to ensure that these do not alter the sense of the text). Pierre Bourdieu's essay "The Field of Cultural Production" depicts the publishing industry as a "space of literary or artistic position-takings," also called the "field of struggles," which is defined by the tension and movement inherent among the various positions in the field. Bourdieu claims that the "field of position-takings [...] is not the product of coherence-seeking intention or objective consensus," meaning that an industry characterized by position-takings is not one of harmony and neutrality.

For self-published books, this is often a more economical option than conducting a print run of hundreds or thousands of books. Many companies, such as Createspace (owned by Amazon.com), Outskirts Press, Blurb, Lulu, Llumina Press, ReadersMagnet, and iUniverse, allow printing single books at per-book costs not much higher than those paid by publishing companies for large print runs. Traditional publishing With commissioned publishing, the publisher makes all the publication arrangements and the author covers all expenses. The author of a work may receive a percentage calculated on a wholesale or a specific price or a fixed amount on each book sold. Publishers, at times, reduced the risk of this type of arrangement, by agreeing only to pay this after a certain number of copies had sold. In Canada, this practice occurred during the 1890s, but was not commonplace until the 1920s. Established and successful authors may receive advance payments, set against future royalties, but this is no longer common practice. Most independent publishers pay royalties as a percentage of net receipts – how net receipts are calculated varies from publisher to publisher. Under this arrangement, the author does not pay anything towards the expense of publication. The costs and financial risk are all carried by the publisher, who will then take the greatest percentage of the receipts. See Compensation for more. Vanity publishing This type of publisher normally charges a flat fee for arranging publication, offers a platform for selling, and then takes a percentage of the sale of every copy of a book. The author receives the rest of the money made. Relationship with editor The relationship between the author and the editor, often the author's only liaison to the publishing company, is often characterized as the site of tension. For the author to reach their audience, often through publication, the work usually must attract the attention of the editor. The idea of the author as the sole meaning-maker of necessity changes to include the influences of the editor and the publisher in order to engage the audience in writing as a social act. There are three principal areas covered by editors – Proofing (checking the Grammar and spelling, looking for typing errors), Story (potentially an area of deep angst for both author and publisher), and Layout (the setting of the final proof ready for publishing often requires minor text changes so a layout editor is required to ensure that these do not alter the sense of the text). Pierre Bourdieu's essay "The Field of Cultural Production" depicts the publishing industry as a "space of literary or artistic position-takings," also called the "field of struggles," which is defined by the tension and movement inherent among the various positions in the field. Bourdieu claims that the "field of position-takings [...] is not the product of coherence-seeking intention or objective consensus," meaning that an industry characterized by position-takings is not one of harmony and neutrality.

In particular for the writer, their authorship in their work makes their work part of their identity, and there is much at stake personally over the negotiation of authority over that identity. However, it is the editor who has "the power to impose the dominant definition of the writer and therefore to delimit the population of those entitled to take part in the struggle to define the writer". As "cultural investors," publishers rely on the editor position to identify a good investment in "cultural capital" which may grow to yield economic capital across all positions. According to the studies of James Curran, the system of shared values among editors in Britain has generated a pressure among authors to write to fit the editors' expectations, removing the focus from the reader-audience and putting a strain on the relationship between authors and editors and on writing as a social act. Even the book review by the editors has more significance than the readership's reception. Compensation Authors rely on advance fees, royalty payments, adaptation of work to a screenplay, and fees collected from giving speeches. A standard contract for an author will usually include provision for payment in the form of an advance and royalties. An advance is a lump sum paid in advance of publication. An advance must be earned out before royalties are payable. An advance may be paid in two lump sums: the first payment on contract signing, and the second on delivery of the completed manuscript or on publication. Royalty payment is the sum paid to authors for each copy of a book sold and is traditionally around 10-12%, but self-published authors can earn about 40% – 60% royalties per each book sale. An author's contract may specify, for example, that they will earn 10% of the retail price of each book sold. Some contracts specify a scale of royalties payable (for example, where royalties start at 10% for the first 10,000 sales, but then increase to a higher percentage rate at higher sale thresholds). An author's book must earn the advance before any further royalties are paid. For example, if an author is paid a modest advance of $2000, and their royalty rate is 10% of a book priced at $20 – that is, $2 per book – the book will need to sell 1000 copies before any further payment will be made. Publishers typically withhold payment of a percentage of royalties earned against returns. In some countries, authors also earn income from a government scheme such as the ELR (educational lending right) and PLR (public lending right) schemes in Australia. Under these schemes, authors are paid a fee for the number of copies of their books in educational and/or public libraries. These days, many authors supplement their income from book sales with public speaking engagements, school visits, residencies, grants, and teaching positions.

In particular for the writer, their authorship in their work makes their work part of their identity, and there is much at stake personally over the negotiation of authority over that identity. However, it is the editor who has "the power to impose the dominant definition of the writer and therefore to delimit the population of those entitled to take part in the struggle to define the writer". As "cultural investors," publishers rely on the editor position to identify a good investment in "cultural capital" which may grow to yield economic capital across all positions. According to the studies of James Curran, the system of shared values among editors in Britain has generated a pressure among authors to write to fit the editors' expectations, removing the focus from the reader-audience and putting a strain on the relationship between authors and editors and on writing as a social act. Even the book review by the editors has more significance than the readership's reception. Compensation Authors rely on advance fees, royalty payments, adaptation of work to a screenplay, and fees collected from giving speeches. A standard contract for an author will usually include provision for payment in the form of an advance and royalties. An advance is a lump sum paid in advance of publication. An advance must be earned out before royalties are payable. An advance may be paid in two lump sums: the first payment on contract signing, and the second on delivery of the completed manuscript or on publication. Royalty payment is the sum paid to authors for each copy of a book sold and is traditionally around 10-12%, but self-published authors can earn about 40% – 60% royalties per each book sale. An author's contract may specify, for example, that they will earn 10% of the retail price of each book sold. Some contracts specify a scale of royalties payable (for example, where royalties start at 10% for the first 10,000 sales, but then increase to a higher percentage rate at higher sale thresholds). An author's book must earn the advance before any further royalties are paid. For example, if an author is paid a modest advance of $2000, and their royalty rate is 10% of a book priced at $20 – that is, $2 per book – the book will need to sell 1000 copies before any further payment will be made. Publishers typically withhold payment of a percentage of royalties earned against returns. In some countries, authors also earn income from a government scheme such as the ELR (educational lending right) and PLR (public lending right) schemes in Australia. Under these schemes, authors are paid a fee for the number of copies of their books in educational and/or public libraries. These days, many authors supplement their income from book sales with public speaking engagements, school visits, residencies, grants, and teaching positions.

In particular for the writer, their authorship in their work makes their work part of their identity, and there is much at stake personally over the negotiation of authority over that identity. However, it is the editor who has "the power to impose the dominant definition of the writer and therefore to delimit the population of those entitled to take part in the struggle to define the writer". As "cultural investors," publishers rely on the editor position to identify a good investment in "cultural capital" which may grow to yield economic capital across all positions. According to the studies of James Curran, the system of shared values among editors in Britain has generated a pressure among authors to write to fit the editors' expectations, removing the focus from the reader-audience and putting a strain on the relationship between authors and editors and on writing as a social act. Even the book review by the editors has more significance than the readership's reception. Compensation Authors rely on advance fees, royalty payments, adaptation of work to a screenplay, and fees collected from giving speeches. A standard contract for an author will usually include provision for payment in the form of an advance and royalties. An advance is a lump sum paid in advance of publication. An advance must be earned out before royalties are payable. An advance may be paid in two lump sums: the first payment on contract signing, and the second on delivery of the completed manuscript or on publication. Royalty payment is the sum paid to authors for each copy of a book sold and is traditionally around 10-12%, but self-published authors can earn about 40% – 60% royalties per each book sale. An author's contract may specify, for example, that they will earn 10% of the retail price of each book sold. Some contracts specify a scale of royalties payable (for example, where royalties start at 10% for the first 10,000 sales, but then increase to a higher percentage rate at higher sale thresholds). An author's book must earn the advance before any further royalties are paid. For example, if an author is paid a modest advance of $2000, and their royalty rate is 10% of a book priced at $20 – that is, $2 per book – the book will need to sell 1000 copies before any further payment will be made. Publishers typically withhold payment of a percentage of royalties earned against returns. In some countries, authors also earn income from a government scheme such as the ELR (educational lending right) and PLR (public lending right) schemes in Australia. Under these schemes, authors are paid a fee for the number of copies of their books in educational and/or public libraries. These days, many authors supplement their income from book sales with public speaking engagements, school visits, residencies, grants, and teaching positions.

Ghostwriters, technical writers, and textbooks writers are typically paid in a different way: usually a set fee or a per word rate rather than on a percentage of sales. In the year 2016, according to the U.S. Bureau of Labor Statistics, nearly 130,000 people worked in the U.S. as authors making an average of $61,240 per year. See also Academic authorship Auteur Authors' editor Distributive writing Lead author List of novelists Lists of poets Lists of writers Novelist Professional writing References Writing occupations Literary criticism

Ghostwriters, technical writers, and textbooks writers are typically paid in a different way: usually a set fee or a per word rate rather than on a percentage of sales. In the year 2016, according to the U.S. Bureau of Labor Statistics, nearly 130,000 people worked in the U.S. as authors making an average of $61,240 per year. See also Academic authorship Auteur Authors' editor Distributive writing Lead author List of novelists Lists of poets Lists of writers Novelist Professional writing References Writing occupations Literary criticism

Ghostwriters, technical writers, and textbooks writers are typically paid in a different way: usually a set fee or a per word rate rather than on a percentage of sales. In the year 2016, according to the U.S. Bureau of Labor Statistics, nearly 130,000 people worked in the U.S. as authors making an average of $61,240 per year. See also Academic authorship Auteur Authors' editor Distributive writing Lead author List of novelists Lists of poets Lists of writers Novelist Professional writing References Writing occupations Literary criticism

Andrey Markov Andrey Andreyevich Markov (14 June 1856 – 20 July 1922) was a Russian mathematician best known for his work on stochastic processes. A primary subject of his research later became known as Markov chains or Markov processes. Markov and his younger brother Vladimir Andreevich Markov (1871–1897) proved the Markov brothers' inequality. His son, another Andrey Andreyevich Markov (1903–1979), was also a notable mathematician, making contributions to constructive mathematics and recursive function theory. Biography Andrey Markov was born on 14 June 1856 in Russia. He attended the St. Petersburg Grammar School, where some teachers saw him as a rebellious student. In his academics he performed poorly in most subjects other than mathematics. Later in life he attended Saint Petersburg Imperial University (now Saint Petersburg State University). among his teachers were Yulian Sokhotski (differential calculus, higher algebra), Konstantin Posse (analytic geometry), Yegor Zolotarev (integral calculus), Pafnuty Chebyshev (number theory and probability theory), Aleksandr Korkin (ordinary and partial differential equations), Mikhail Okatov (mechanism theory), Osip Somov (mechanics), and Nikolai Budajev (descriptive and higher geometry). He completed his studies at the university and was later asked if he would like to stay and have a career as a Mathematician. He later taught at high schools and continued his own mathematical studies. In this time he found a practical use for his mathematical skills. He figured out that he could use chains to model the alliteration of vowels and consonants in Russian literature. He also contributed to many other mathematical aspects in his time. He died at age 66 on 20 July 1922. Timeline In 1877, Markov was awarded a gold medal for his outstanding solution of the problem About Integration of Differential Equations by Continued Fractions with an Application to the Equation . During the following year, he passed the candidate's examinations, and he remained at the university to prepare for a lecturer's position. In April 1880, Markov defended his master's thesis "On the Binary Square Forms with Positive Determinant", which was directed by Aleksandr Korkin and Yegor Zolotarev. Four years later in 1884, he defended his doctoral thesis titled "On Certain Applications of the Algebraic Continuous Fractions". His pedagogical work began after the defense of his master's thesis in autumn 1880. As a privatdozent he lectured on differential and integral calculus. Later he lectured alternately on "introduction to analysis", probability theory (succeeding Chebyshev, who had left the university in 1882) and the calculus of differences. From 1895 through 1905 he also lectured in differential calculus. One year after the defense of his doctoral thesis, Markov was appointed extraordinary professor (1886) and in the same year he was elected adjunct to the Academy of Sciences. In 1890, after the death of Viktor Bunyakovsky, Markov became an extraordinary member of the academy. His promotion to an ordinary professor of St. Petersburg University followed in the fall of 1894. In 1896, Markov was elected an ordinary member of the academy as the successor of Chebyshev.

Andrey Markov Andrey Andreyevich Markov (14 June 1856 – 20 July 1922) was a Russian mathematician best known for his work on stochastic processes. A primary subject of his research later became known as Markov chains or Markov processes. Markov and his younger brother Vladimir Andreevich Markov (1871–1897) proved the Markov brothers' inequality. His son, another Andrey Andreyevich Markov (1903–1979), was also a notable mathematician, making contributions to constructive mathematics and recursive function theory. Biography Andrey Markov was born on 14 June 1856 in Russia. He attended the St. Petersburg Grammar School, where some teachers saw him as a rebellious student. In his academics he performed poorly in most subjects other than mathematics. Later in life he attended Saint Petersburg Imperial University (now Saint Petersburg State University). among his teachers were Yulian Sokhotski (differential calculus, higher algebra), Konstantin Posse (analytic geometry), Yegor Zolotarev (integral calculus), Pafnuty Chebyshev (number theory and probability theory), Aleksandr Korkin (ordinary and partial differential equations), Mikhail Okatov (mechanism theory), Osip Somov (mechanics), and Nikolai Budajev (descriptive and higher geometry). He completed his studies at the university and was later asked if he would like to stay and have a career as a Mathematician. He later taught at high schools and continued his own mathematical studies. In this time he found a practical use for his mathematical skills. He figured out that he could use chains to model the alliteration of vowels and consonants in Russian literature. He also contributed to many other mathematical aspects in his time. He died at age 66 on 20 July 1922. Timeline In 1877, Markov was awarded a gold medal for his outstanding solution of the problem About Integration of Differential Equations by Continued Fractions with an Application to the Equation . During the following year, he passed the candidate's examinations, and he remained at the university to prepare for a lecturer's position. In April 1880, Markov defended his master's thesis "On the Binary Square Forms with Positive Determinant", which was directed by Aleksandr Korkin and Yegor Zolotarev. Four years later in 1884, he defended his doctoral thesis titled "On Certain Applications of the Algebraic Continuous Fractions". His pedagogical work began after the defense of his master's thesis in autumn 1880. As a privatdozent he lectured on differential and integral calculus. Later he lectured alternately on "introduction to analysis", probability theory (succeeding Chebyshev, who had left the university in 1882) and the calculus of differences. From 1895 through 1905 he also lectured in differential calculus. One year after the defense of his doctoral thesis, Markov was appointed extraordinary professor (1886) and in the same year he was elected adjunct to the Academy of Sciences. In 1890, after the death of Viktor Bunyakovsky, Markov became an extraordinary member of the academy. His promotion to an ordinary professor of St. Petersburg University followed in the fall of 1894. In 1896, Markov was elected an ordinary member of the academy as the successor of Chebyshev.

In 1905, he was appointed merited professor and was granted the right to retire, which he did immediately. Until 1910, however, he continued to lecture in the calculus of differences. In connection with student riots in 1908, professors and lecturers of St. Petersburg University were ordered to monitor their students. Markov refused to accept this decree, and he wrote an explanation in which he declined to be an "agent of the governance". Markov was removed from further teaching duties at St. Petersburg University, and hence he decided to retire from the university. Markov was an atheist. In 1912, he protested Leo Tolstoy's excommunication from the Russian Orthodox Church by requesting his own excommunication. The Church complied with his request. In 1913, the council of St. Petersburg elected nine scientists honorary members of the university. Markov was among them, but his election was not affirmed by the minister of education. The affirmation only occurred four years later, after the February Revolution in 1917. Markov then resumed his teaching activities and lectured on probability theory and the calculus of differences until his death in 1922. See also List of things named after Andrey Markov Chebyshev–Markov–Stieltjes inequalities Gauss–Markov theorem Gauss–Markov process Hidden Markov model Markov blanket Markov chain Markov decision process Markov's inequality Markov brothers' inequality Markov information source Markov network Markov number Markov property Markov process Stochastic matrix (also known as Markov matrix) Subjunctive possibility Notes References Further reading А. А. Марков. "Распространение закона больших чисел на величины, зависящие друг от друга". "Известия Физико-математического общества при Казанском университете", 2-я серия, том 15, с. 135–156, 1906. A. A. Markov. "Extension of the limit theorems of probability theory to a sum of variables connected in a chain". reprinted in Appendix B of: R. Howard. Dynamic Probabilistic Systems, volume 1: Markov Chains. John Wiley and Sons, 1971. External links Markov, Andrei Andreyevich Markov, Andrei Andreyevich 19th-century Russian mathematicians 20th-century Russian mathematicians Russian atheists Former Russian Orthodox Christians Probability theorists Saint Petersburg State University alumni Full members of the Saint Petersburg Academy of Sciences Full Members of the Russian Academy of Sciences (1917–1925) People from Ryazan Russian statisticians

In 1905, he was appointed merited professor and was granted the right to retire, which he did immediately. Until 1910, however, he continued to lecture in the calculus of differences. In connection with student riots in 1908, professors and lecturers of St. Petersburg University were ordered to monitor their students. Markov refused to accept this decree, and he wrote an explanation in which he declined to be an "agent of the governance". Markov was removed from further teaching duties at St. Petersburg University, and hence he decided to retire from the university. Markov was an atheist. In 1912, he protested Leo Tolstoy's excommunication from the Russian Orthodox Church by requesting his own excommunication. The Church complied with his request. In 1913, the council of St. Petersburg elected nine scientists honorary members of the university. Markov was among them, but his election was not affirmed by the minister of education. The affirmation only occurred four years later, after the February Revolution in 1917. Markov then resumed his teaching activities and lectured on probability theory and the calculus of differences until his death in 1922. See also List of things named after Andrey Markov Chebyshev–Markov–Stieltjes inequalities Gauss–Markov theorem Gauss–Markov process Hidden Markov model Markov blanket Markov chain Markov decision process Markov's inequality Markov brothers' inequality Markov information source Markov network Markov number Markov property Markov process Stochastic matrix (also known as Markov matrix) Subjunctive possibility Notes References Further reading А. А. Марков. "Распространение закона больших чисел на величины, зависящие друг от друга". "Известия Физико-математического общества при Казанском университете", 2-я серия, том 15, с. 135–156, 1906. A. A. Markov. "Extension of the limit theorems of probability theory to a sum of variables connected in a chain". reprinted in Appendix B of: R. Howard. Dynamic Probabilistic Systems, volume 1: Markov Chains. John Wiley and Sons, 1971. External links Markov, Andrei Andreyevich Markov, Andrei Andreyevich 19th-century Russian mathematicians 20th-century Russian mathematicians Russian atheists Former Russian Orthodox Christians Probability theorists Saint Petersburg State University alumni Full members of the Saint Petersburg Academy of Sciences Full Members of the Russian Academy of Sciences (1917–1925) People from Ryazan Russian statisticians

In 1905, he was appointed merited professor and was granted the right to retire, which he did immediately. Until 1910, however, he continued to lecture in the calculus of differences. In connection with student riots in 1908, professors and lecturers of St. Petersburg University were ordered to monitor their students. Markov refused to accept this decree, and he wrote an explanation in which he declined to be an "agent of the governance". Markov was removed from further teaching duties at St. Petersburg University, and hence he decided to retire from the university. Markov was an atheist. In 1912, he protested Leo Tolstoy's excommunication from the Russian Orthodox Church by requesting his own excommunication. The Church complied with his request. In 1913, the council of St. Petersburg elected nine scientists honorary members of the university. Markov was among them, but his election was not affirmed by the minister of education. The affirmation only occurred four years later, after the February Revolution in 1917. Markov then resumed his teaching activities and lectured on probability theory and the calculus of differences until his death in 1922. See also List of things named after Andrey Markov Chebyshev–Markov–Stieltjes inequalities Gauss–Markov theorem Gauss–Markov process Hidden Markov model Markov blanket Markov chain Markov decision process Markov's inequality Markov brothers' inequality Markov information source Markov network Markov number Markov property Markov process Stochastic matrix (also known as Markov matrix) Subjunctive possibility Notes References Further reading А. А. Марков. "Распространение закона больших чисел на величины, зависящие друг от друга". "Известия Физико-математического общества при Казанском университете", 2-я серия, том 15, с. 135–156, 1906. A. A. Markov. "Extension of the limit theorems of probability theory to a sum of variables connected in a chain". reprinted in Appendix B of: R. Howard. Dynamic Probabilistic Systems, volume 1: Markov Chains. John Wiley and Sons, 1971. External links Markov, Andrei Andreyevich Markov, Andrei Andreyevich 19th-century Russian mathematicians 20th-century Russian mathematicians Russian atheists Former Russian Orthodox Christians Probability theorists Saint Petersburg State University alumni Full members of the Saint Petersburg Academy of Sciences Full Members of the Russian Academy of Sciences (1917–1925) People from Ryazan Russian statisticians

Angst Angst is fear or anxiety (anguish is its Latinate equivalent, and the words anxious and anxiety are of similar origin). The dictionary definition for angst is a feeling of anxiety, apprehension, or insecurity. Etymology The word angst was introduced into English from the Danish, Norwegian, and Dutch word and the German word . It is attested since the 19th century in English translations of the works of Kierkegaard and Freud. It is used in English to describe an intense feeling of apprehension, anxiety, or inner turmoil. In other languages (with words from the Latin for "fear" or "panic"), the derived words differ in meaning; for example, as in the French and . The word angst has existed since the 8th century, from the Proto-Indo-European root , "restraint" from which Old High German developed. It is pre-cognate with the Latin , "tensity, tightness" and , "choking, clogging"; compare to the Ancient Greek () "strangle". Existentialist angst In existentialist philosophy, the term angst carries a specific conceptual meaning. The use of the term was first attributed to Danish philosopher Søren Kierkegaard (1813–1855). In The Concept of Anxiety (also known as The Concept of Dread, depending on the translation), Kierkegaard used the word Angest (in common Danish, angst, meaning "dread" or "anxiety") to describe a profound and deep-seated condition. Where non-human animals are guided solely by instinct, said Kierkegaard, human beings enjoy a freedom of choice that we find both appealing and terrifying. It is the anxiety of understanding of being free when considering undefined possibilities of one's life and the immense responsibility of having the power of choice over them. Kierkegaard's concept of angst reappeared in the works of existentialist philosophers who followed, such as Friedrich Nietzsche, Jean-Paul Sartre, and Martin Heidegger, each of whom developed the idea further in individual ways. While Kierkegaard's angst referred mainly to ambiguous feelings about moral freedom within a religious personal belief system, later existentialists discussed conflicts of personal principles, cultural norms, and existential despair. Music Existential angst makes its appearance in classical musical composition in the early twentieth century as a result of both philosophical developments and as a reflection of the war-torn times. Notable composers whose works are often linked with the concept include Gustav Mahler, Richard Strauss (operas Elektra and Salome), Claude-Achille Debussy (opera Pelleas et Melisande, ballet Jeux, other works), Jean Sibelius (especially the Fourth Symphony), Arnold Schoenberg (A Survivor from Warsaw, other works), Alban Berg, Francis Poulenc (opera Dialogues of the Carmelites), Dmitri Shostakovich (opera Lady Macbeth of the Mtsensk District, symphonies and chamber music), Béla Bartók (opera Bluebeard's Castle, other works), and Krzysztof Penderecki (especially Threnody to the Victims of Hiroshima). Angst began to be discussed in reference to popular music in the mid- to late 1950s amid widespread concerns over international tensions and nuclear proliferation. Jeff Nuttall's book Bomb Culture (1968) traced angst in popular culture to Hiroshima.

Angst Angst is fear or anxiety (anguish is its Latinate equivalent, and the words anxious and anxiety are of similar origin). The dictionary definition for angst is a feeling of anxiety, apprehension, or insecurity. Etymology The word angst was introduced into English from the Danish, Norwegian, and Dutch word and the German word . It is attested since the 19th century in English translations of the works of Kierkegaard and Freud. It is used in English to describe an intense feeling of apprehension, anxiety, or inner turmoil. In other languages (with words from the Latin for "fear" or "panic"), the derived words differ in meaning; for example, as in the French and . The word angst has existed since the 8th century, from the Proto-Indo-European root , "restraint" from which Old High German developed. It is pre-cognate with the Latin , "tensity, tightness" and , "choking, clogging"; compare to the Ancient Greek () "strangle". Existentialist angst In existentialist philosophy, the term angst carries a specific conceptual meaning. The use of the term was first attributed to Danish philosopher Søren Kierkegaard (1813–1855). In The Concept of Anxiety (also known as The Concept of Dread, depending on the translation), Kierkegaard used the word Angest (in common Danish, angst, meaning "dread" or "anxiety") to describe a profound and deep-seated condition. Where non-human animals are guided solely by instinct, said Kierkegaard, human beings enjoy a freedom of choice that we find both appealing and terrifying. It is the anxiety of understanding of being free when considering undefined possibilities of one's life and the immense responsibility of having the power of choice over them. Kierkegaard's concept of angst reappeared in the works of existentialist philosophers who followed, such as Friedrich Nietzsche, Jean-Paul Sartre, and Martin Heidegger, each of whom developed the idea further in individual ways. While Kierkegaard's angst referred mainly to ambiguous feelings about moral freedom within a religious personal belief system, later existentialists discussed conflicts of personal principles, cultural norms, and existential despair. Music Existential angst makes its appearance in classical musical composition in the early twentieth century as a result of both philosophical developments and as a reflection of the war-torn times. Notable composers whose works are often linked with the concept include Gustav Mahler, Richard Strauss (operas Elektra and Salome), Claude-Achille Debussy (opera Pelleas et Melisande, ballet Jeux, other works), Jean Sibelius (especially the Fourth Symphony), Arnold Schoenberg (A Survivor from Warsaw, other works), Alban Berg, Francis Poulenc (opera Dialogues of the Carmelites), Dmitri Shostakovich (opera Lady Macbeth of the Mtsensk District, symphonies and chamber music), Béla Bartók (opera Bluebeard's Castle, other works), and Krzysztof Penderecki (especially Threnody to the Victims of Hiroshima). Angst began to be discussed in reference to popular music in the mid- to late 1950s amid widespread concerns over international tensions and nuclear proliferation. Jeff Nuttall's book Bomb Culture (1968) traced angst in popular culture to Hiroshima.

Dread was expressed in works of folk rock such as Bob Dylan's "Masters of War" (1963) and "A Hard Rain's a-Gonna Fall". The term often makes an appearance in reference to punk rock, grunge, nu metal, and works of emo where expressions of melancholy, existential despair, or nihilism predominate. See also References External links Anxiety Emotions Existentialist concepts

Dread was expressed in works of folk rock such as Bob Dylan's "Masters of War" (1963) and "A Hard Rain's a-Gonna Fall". The term often makes an appearance in reference to punk rock, grunge, nu metal, and works of emo where expressions of melancholy, existential despair, or nihilism predominate. See also References External links Anxiety Emotions Existentialist concepts

Dread was expressed in works of folk rock such as Bob Dylan's "Masters of War" (1963) and "A Hard Rain's a-Gonna Fall". The term often makes an appearance in reference to punk rock, grunge, nu metal, and works of emo where expressions of melancholy, existential despair, or nihilism predominate. See also References External links Anxiety Emotions Existentialist concepts

Anxiety Anxiety is an emotion characterized by an unpleasant state of inner turmoil and includes subjectively unpleasant feelings of dread over anticipated events. It is often accompanied by nervous behavior such as pacing back and forth, somatic complaints, and rumination. Anxiety is a feeling of uneasiness and worry, usually generalized and unfocused as an overreaction to a situation that is only subjectively seen as menacing. It is often accompanied by muscular tension, restlessness, fatigue, inability to catch one's breath, tightness in the abdominal region, and problems in concentration. Anxiety is closely related to fear, which is a response to a real or perceived immediate threat; anxiety involves the expectation of future threat including dread. People facing anxiety may withdraw from situations which have provoked anxiety in the past. Though anxiety is a normal human response, when excessive or persisting beyond developmentally appropriate periods it may be diagnosed as an anxiety disorder. There are multiple forms of anxiety disorder (such as Generalized Anxiety Disorder and Obsessive Compulsive Disorder) with specific clinical definitions. Part of the definition of an anxiety disorder, which distinguishes it from every day anxiety, is that it is persistent, typically lasting 6 months or more, although the criterion for duration is intended as a general guide with allowance for some degree of flexibility and is sometimes of shorter duration in children. Anxiety vs. fear Anxiety is distinguished from fear, which is an appropriate cognitive and emotional response to a perceived threat. Anxiety is related to the specific behaviors of fight-or-flight responses, defensive behavior or escape. There is a false presumption that often circulates that anxiety only occurs in situations perceived as uncontrollable or unavoidable, but this is not always so. David Barlow defines anxiety as "a future-oriented mood state in which one is not ready or prepared to attempt to cope with upcoming negative events," and that it is a distinction between future and present dangers which divides anxiety and fear. Another description of anxiety is agony, dread, terror, or even apprehension. In positive psychology, anxiety is described as the mental state that results from a difficult challenge for which the subject has insufficient coping skills. Fear and anxiety can be differentiated into four domains: (1) duration of emotional experience, (2) temporal focus, (3) specificity of the threat, and (4) motivated direction. Fear is short-lived, present-focused, geared towards a specific threat, and facilitating escape from threat. On the other hand, anxiety is long-acting, future-focused, broadly focused towards a diffuse threat, and promoting excessive caution while approaching a potential threat and interferes with constructive coping. Joseph E. LeDoux and Lisa Feldman Barrett have both sought to separate automatic threat responses from additional associated cognitive activity within anxiety. Symptoms Anxiety can be experienced with long, drawn-out daily symptoms that reduce quality of life, known as chronic (or generalized) anxiety, or it can be experienced in short spurts with sporadic, stressful panic attacks, known as acute anxiety. Symptoms of anxiety can range in number, intensity, and frequency, depending on the person.

Anxiety Anxiety is an emotion characterized by an unpleasant state of inner turmoil and includes subjectively unpleasant feelings of dread over anticipated events. It is often accompanied by nervous behavior such as pacing back and forth, somatic complaints, and rumination. Anxiety is a feeling of uneasiness and worry, usually generalized and unfocused as an overreaction to a situation that is only subjectively seen as menacing. It is often accompanied by muscular tension, restlessness, fatigue, inability to catch one's breath, tightness in the abdominal region, and problems in concentration. Anxiety is closely related to fear, which is a response to a real or perceived immediate threat; anxiety involves the expectation of future threat including dread. People facing anxiety may withdraw from situations which have provoked anxiety in the past. Though anxiety is a normal human response, when excessive or persisting beyond developmentally appropriate periods it may be diagnosed as an anxiety disorder. There are multiple forms of anxiety disorder (such as Generalized Anxiety Disorder and Obsessive Compulsive Disorder) with specific clinical definitions. Part of the definition of an anxiety disorder, which distinguishes it from every day anxiety, is that it is persistent, typically lasting 6 months or more, although the criterion for duration is intended as a general guide with allowance for some degree of flexibility and is sometimes of shorter duration in children. Anxiety vs. fear Anxiety is distinguished from fear, which is an appropriate cognitive and emotional response to a perceived threat. Anxiety is related to the specific behaviors of fight-or-flight responses, defensive behavior or escape. There is a false presumption that often circulates that anxiety only occurs in situations perceived as uncontrollable or unavoidable, but this is not always so. David Barlow defines anxiety as "a future-oriented mood state in which one is not ready or prepared to attempt to cope with upcoming negative events," and that it is a distinction between future and present dangers which divides anxiety and fear. Another description of anxiety is agony, dread, terror, or even apprehension. In positive psychology, anxiety is described as the mental state that results from a difficult challenge for which the subject has insufficient coping skills. Fear and anxiety can be differentiated into four domains: (1) duration of emotional experience, (2) temporal focus, (3) specificity of the threat, and (4) motivated direction. Fear is short-lived, present-focused, geared towards a specific threat, and facilitating escape from threat. On the other hand, anxiety is long-acting, future-focused, broadly focused towards a diffuse threat, and promoting excessive caution while approaching a potential threat and interferes with constructive coping. Joseph E. LeDoux and Lisa Feldman Barrett have both sought to separate automatic threat responses from additional associated cognitive activity within anxiety. Symptoms Anxiety can be experienced with long, drawn-out daily symptoms that reduce quality of life, known as chronic (or generalized) anxiety, or it can be experienced in short spurts with sporadic, stressful panic attacks, known as acute anxiety. Symptoms of anxiety can range in number, intensity, and frequency, depending on the person.

While almost everyone has experienced anxiety at some point in their lives, most do not develop long-term problems with anxiety. Anxiety may cause psychiatric and physiological symptoms. The risk of anxiety leading to depression could possibly even lead to an individual harming themselves, which is why there are many 24-hour suicide prevention hotlines. The behavioral effects of anxiety may include withdrawal from situations which have provoked anxiety or negative feelings in the past. Other effects may include changes in sleeping patterns, changes in habits, increase or decrease in food intake, and increased motor tension (such as foot tapping). The emotional effects of anxiety may include "feelings of apprehension or dread, trouble concentrating, feeling tense or jumpy, anticipating the worst, irritability, restlessness, watching (and waiting) for signs (and occurrences) of danger, and, feeling like your mind's gone blank" as well as "nightmares/bad dreams, obsessions about sensations, déjà vu, a trapped-in-your-mind feeling, and feeling like everything is scary." It may include a vague experience and feeling of helplessness. The cognitive effects of anxiety may include thoughts about suspected dangers, such as fear of dying: "You may ... fear that the chest pains are a deadly heart attack or that the shooting pains in your head are the result of a tumor or an aneurysm. You feel an intense fear when you think of dying, or you may think of it more often than normal, or can't get it out of your mind." The physiological symptoms of anxiety may include: Neurological, as headache, paresthesias, fasciculations, vertigo, or presyncope. Digestive, as abdominal pain, nausea, diarrhea, indigestion, dry mouth, or bolus. Stress hormones released in an anxious state have an impact on bowel function and can manifest physical symptoms that may contribute to or exacerbate IBS. Respiratory, as shortness of breath or sighing breathing. Cardiac, as palpitations, tachycardia, or chest pain. Muscular, as fatigue, tremors, or tetany. Cutaneous, as perspiration, or itchy skin. Uro-genital, as frequent urination, urinary urgency, dyspareunia, or impotence, chronic pelvic pain syndrome. Types There are various types of anxiety. Existential anxiety can occur when a person faces angst, an existential crisis, or nihilistic feelings. People can also face mathematical anxiety, somatic anxiety, stage fright, or test anxiety. Social anxiety refers to a fear of rejection and negative evaluation (being judged) by other people. Existential The philosopher Søren Kierkegaard, in The Concept of Anxiety (1844), described anxiety or dread associated with the "dizziness of freedom" and suggested the possibility for positive resolution of anxiety through the self-conscious exercise of responsibility and choosing. In Art and Artist (1932), the psychologist Otto Rank wrote that the psychological trauma of birth was the pre-eminent human symbol of existential anxiety and encompasses the creative person's simultaneous fear of – and desire for – separation, individuation, and differentiation.

While almost everyone has experienced anxiety at some point in their lives, most do not develop long-term problems with anxiety. Anxiety may cause psychiatric and physiological symptoms. The risk of anxiety leading to depression could possibly even lead to an individual harming themselves, which is why there are many 24-hour suicide prevention hotlines. The behavioral effects of anxiety may include withdrawal from situations which have provoked anxiety or negative feelings in the past. Other effects may include changes in sleeping patterns, changes in habits, increase or decrease in food intake, and increased motor tension (such as foot tapping). The emotional effects of anxiety may include "feelings of apprehension or dread, trouble concentrating, feeling tense or jumpy, anticipating the worst, irritability, restlessness, watching (and waiting) for signs (and occurrences) of danger, and, feeling like your mind's gone blank" as well as "nightmares/bad dreams, obsessions about sensations, déjà vu, a trapped-in-your-mind feeling, and feeling like everything is scary." It may include a vague experience and feeling of helplessness. The cognitive effects of anxiety may include thoughts about suspected dangers, such as fear of dying: "You may ... fear that the chest pains are a deadly heart attack or that the shooting pains in your head are the result of a tumor or an aneurysm. You feel an intense fear when you think of dying, or you may think of it more often than normal, or can't get it out of your mind." The physiological symptoms of anxiety may include: Neurological, as headache, paresthesias, fasciculations, vertigo, or presyncope. Digestive, as abdominal pain, nausea, diarrhea, indigestion, dry mouth, or bolus. Stress hormones released in an anxious state have an impact on bowel function and can manifest physical symptoms that may contribute to or exacerbate IBS. Respiratory, as shortness of breath or sighing breathing. Cardiac, as palpitations, tachycardia, or chest pain. Muscular, as fatigue, tremors, or tetany. Cutaneous, as perspiration, or itchy skin. Uro-genital, as frequent urination, urinary urgency, dyspareunia, or impotence, chronic pelvic pain syndrome. Types There are various types of anxiety. Existential anxiety can occur when a person faces angst, an existential crisis, or nihilistic feelings. People can also face mathematical anxiety, somatic anxiety, stage fright, or test anxiety. Social anxiety refers to a fear of rejection and negative evaluation (being judged) by other people. Existential The philosopher Søren Kierkegaard, in The Concept of Anxiety (1844), described anxiety or dread associated with the "dizziness of freedom" and suggested the possibility for positive resolution of anxiety through the self-conscious exercise of responsibility and choosing. In Art and Artist (1932), the psychologist Otto Rank wrote that the psychological trauma of birth was the pre-eminent human symbol of existential anxiety and encompasses the creative person's simultaneous fear of – and desire for – separation, individuation, and differentiation.

While almost everyone has experienced anxiety at some point in their lives, most do not develop long-term problems with anxiety. Anxiety may cause psychiatric and physiological symptoms. The risk of anxiety leading to depression could possibly even lead to an individual harming themselves, which is why there are many 24-hour suicide prevention hotlines. The behavioral effects of anxiety may include withdrawal from situations which have provoked anxiety or negative feelings in the past. Other effects may include changes in sleeping patterns, changes in habits, increase or decrease in food intake, and increased motor tension (such as foot tapping). The emotional effects of anxiety may include "feelings of apprehension or dread, trouble concentrating, feeling tense or jumpy, anticipating the worst, irritability, restlessness, watching (and waiting) for signs (and occurrences) of danger, and, feeling like your mind's gone blank" as well as "nightmares/bad dreams, obsessions about sensations, déjà vu, a trapped-in-your-mind feeling, and feeling like everything is scary." It may include a vague experience and feeling of helplessness. The cognitive effects of anxiety may include thoughts about suspected dangers, such as fear of dying: "You may ... fear that the chest pains are a deadly heart attack or that the shooting pains in your head are the result of a tumor or an aneurysm. You feel an intense fear when you think of dying, or you may think of it more often than normal, or can't get it out of your mind." The physiological symptoms of anxiety may include: Neurological, as headache, paresthesias, fasciculations, vertigo, or presyncope. Digestive, as abdominal pain, nausea, diarrhea, indigestion, dry mouth, or bolus. Stress hormones released in an anxious state have an impact on bowel function and can manifest physical symptoms that may contribute to or exacerbate IBS. Respiratory, as shortness of breath or sighing breathing. Cardiac, as palpitations, tachycardia, or chest pain. Muscular, as fatigue, tremors, or tetany. Cutaneous, as perspiration, or itchy skin. Uro-genital, as frequent urination, urinary urgency, dyspareunia, or impotence, chronic pelvic pain syndrome. Types There are various types of anxiety. Existential anxiety can occur when a person faces angst, an existential crisis, or nihilistic feelings. People can also face mathematical anxiety, somatic anxiety, stage fright, or test anxiety. Social anxiety refers to a fear of rejection and negative evaluation (being judged) by other people. Existential The philosopher Søren Kierkegaard, in The Concept of Anxiety (1844), described anxiety or dread associated with the "dizziness of freedom" and suggested the possibility for positive resolution of anxiety through the self-conscious exercise of responsibility and choosing. In Art and Artist (1932), the psychologist Otto Rank wrote that the psychological trauma of birth was the pre-eminent human symbol of existential anxiety and encompasses the creative person's simultaneous fear of – and desire for – separation, individuation, and differentiation.

The theologian Paul Tillich characterized existential anxiety as "the state in which a being is aware of its possible nonbeing" and he listed three categories for the nonbeing and resulting anxiety: ontic (fate and death), moral (guilt and condemnation), and spiritual (emptiness and meaninglessness). According to Tillich, the last of these three types of existential anxiety, i.e. spiritual anxiety, is predominant in modern times while the others were predominant in earlier periods. Tillich argues that this anxiety can be accepted as part of the human condition or it can be resisted but with negative consequences. In its pathological form, spiritual anxiety may tend to "drive the person toward the creation of certitude in systems of meaning which are supported by tradition and authority" even though such "undoubted certitude is not built on the rock of reality". According to Viktor Frankl, the author of Man's Search for Meaning, when a person is faced with extreme mortal dangers, the most basic of all human wishes is to find a meaning of life to combat the "trauma of nonbeing" as death is near. Depending on the source of the threat, psychoanalytic theory distinguishes the following types of anxiety: realistic neurotic moral Test and performance According to Yerkes-Dodson law, an optimal level of arousal is necessary to best complete a task such as an exam, performance, or competitive event. However, when the anxiety or level of arousal exceeds that optimum, the result is a decline in performance. Test anxiety is the uneasiness, apprehension, or nervousness felt by students who have a fear of failing an exam. Students who have test anxiety may experience any of the following: the association of grades with personal worth; fear of embarrassment by a teacher; fear of alienation from parents or friends; time pressures; or feeling a loss of control. Sweating, dizziness, headaches, racing heartbeats, nausea, fidgeting, uncontrollable crying or laughing and drumming on a desk are all common. Because test anxiety hinges on fear of negative evaluation, debate exists as to whether test anxiety is itself a unique anxiety disorder or whether it is a specific type of social phobia. The DSM-IV classifies test anxiety as a type of social phobia. While the term "test anxiety" refers specifically to students, many workers share the same experience with regard to their career or profession. The fear of failing at a task and being negatively evaluated for failure can have a similarly negative effect on the adult. Management of test anxiety focuses on achieving relaxation and developing mechanisms to manage anxiety. Stranger, social, and intergroup anxiety Humans generally require social acceptance and thus sometimes dread the disapproval of others. Apprehension of being judged by others may cause anxiety in social environments. Anxiety during social interactions, particularly between strangers, is common among young people. It may persist into adulthood and become social anxiety or social phobia. "Stranger anxiety" in small children is not considered a phobia.

The theologian Paul Tillich characterized existential anxiety as "the state in which a being is aware of its possible nonbeing" and he listed three categories for the nonbeing and resulting anxiety: ontic (fate and death), moral (guilt and condemnation), and spiritual (emptiness and meaninglessness). According to Tillich, the last of these three types of existential anxiety, i.e. spiritual anxiety, is predominant in modern times while the others were predominant in earlier periods. Tillich argues that this anxiety can be accepted as part of the human condition or it can be resisted but with negative consequences. In its pathological form, spiritual anxiety may tend to "drive the person toward the creation of certitude in systems of meaning which are supported by tradition and authority" even though such "undoubted certitude is not built on the rock of reality". According to Viktor Frankl, the author of Man's Search for Meaning, when a person is faced with extreme mortal dangers, the most basic of all human wishes is to find a meaning of life to combat the "trauma of nonbeing" as death is near. Depending on the source of the threat, psychoanalytic theory distinguishes the following types of anxiety: realistic neurotic moral Test and performance According to Yerkes-Dodson law, an optimal level of arousal is necessary to best complete a task such as an exam, performance, or competitive event. However, when the anxiety or level of arousal exceeds that optimum, the result is a decline in performance. Test anxiety is the uneasiness, apprehension, or nervousness felt by students who have a fear of failing an exam. Students who have test anxiety may experience any of the following: the association of grades with personal worth; fear of embarrassment by a teacher; fear of alienation from parents or friends; time pressures; or feeling a loss of control. Sweating, dizziness, headaches, racing heartbeats, nausea, fidgeting, uncontrollable crying or laughing and drumming on a desk are all common. Because test anxiety hinges on fear of negative evaluation, debate exists as to whether test anxiety is itself a unique anxiety disorder or whether it is a specific type of social phobia. The DSM-IV classifies test anxiety as a type of social phobia. While the term "test anxiety" refers specifically to students, many workers share the same experience with regard to their career or profession. The fear of failing at a task and being negatively evaluated for failure can have a similarly negative effect on the adult. Management of test anxiety focuses on achieving relaxation and developing mechanisms to manage anxiety. Stranger, social, and intergroup anxiety Humans generally require social acceptance and thus sometimes dread the disapproval of others. Apprehension of being judged by others may cause anxiety in social environments. Anxiety during social interactions, particularly between strangers, is common among young people. It may persist into adulthood and become social anxiety or social phobia. "Stranger anxiety" in small children is not considered a phobia.

The theologian Paul Tillich characterized existential anxiety as "the state in which a being is aware of its possible nonbeing" and he listed three categories for the nonbeing and resulting anxiety: ontic (fate and death), moral (guilt and condemnation), and spiritual (emptiness and meaninglessness). According to Tillich, the last of these three types of existential anxiety, i.e. spiritual anxiety, is predominant in modern times while the others were predominant in earlier periods. Tillich argues that this anxiety can be accepted as part of the human condition or it can be resisted but with negative consequences. In its pathological form, spiritual anxiety may tend to "drive the person toward the creation of certitude in systems of meaning which are supported by tradition and authority" even though such "undoubted certitude is not built on the rock of reality". According to Viktor Frankl, the author of Man's Search for Meaning, when a person is faced with extreme mortal dangers, the most basic of all human wishes is to find a meaning of life to combat the "trauma of nonbeing" as death is near. Depending on the source of the threat, psychoanalytic theory distinguishes the following types of anxiety: realistic neurotic moral Test and performance According to Yerkes-Dodson law, an optimal level of arousal is necessary to best complete a task such as an exam, performance, or competitive event. However, when the anxiety or level of arousal exceeds that optimum, the result is a decline in performance. Test anxiety is the uneasiness, apprehension, or nervousness felt by students who have a fear of failing an exam. Students who have test anxiety may experience any of the following: the association of grades with personal worth; fear of embarrassment by a teacher; fear of alienation from parents or friends; time pressures; or feeling a loss of control. Sweating, dizziness, headaches, racing heartbeats, nausea, fidgeting, uncontrollable crying or laughing and drumming on a desk are all common. Because test anxiety hinges on fear of negative evaluation, debate exists as to whether test anxiety is itself a unique anxiety disorder or whether it is a specific type of social phobia. The DSM-IV classifies test anxiety as a type of social phobia. While the term "test anxiety" refers specifically to students, many workers share the same experience with regard to their career or profession. The fear of failing at a task and being negatively evaluated for failure can have a similarly negative effect on the adult. Management of test anxiety focuses on achieving relaxation and developing mechanisms to manage anxiety. Stranger, social, and intergroup anxiety Humans generally require social acceptance and thus sometimes dread the disapproval of others. Apprehension of being judged by others may cause anxiety in social environments. Anxiety during social interactions, particularly between strangers, is common among young people. It may persist into adulthood and become social anxiety or social phobia. "Stranger anxiety" in small children is not considered a phobia.

In adults, an excessive fear of other people is not a developmentally common stage; it is called social anxiety. According to Cutting, social phobics do not fear the crowd but the fact that they may be judged negatively. Social anxiety varies in degree and severity. For some people, it is characterized by experiencing discomfort or awkwardness during physical social contact (e.g. embracing, shaking hands, etc. ), while in other cases it can lead to a fear of interacting with unfamiliar people altogether. Those suffering from this condition may restrict their lifestyles to accommodate the anxiety, minimizing social interaction whenever possible. Social anxiety also forms a core aspect of certain personality disorders, including avoidant personality disorder. To the extent that a person is fearful of social encounters with unfamiliar others, some people may experience anxiety particularly during interactions with outgroup members, or people who share different group memberships (i.e., by race, ethnicity, class, gender, etc.). Depending on the nature of the antecedent relations, cognitions, and situational factors, intergroup contact may be stressful and lead to feelings of anxiety. This apprehension or fear of contact with outgroup members is often called interracial or intergroup anxiety. As is the case with the more generalized forms of social anxiety, intergroup anxiety has behavioral, cognitive, and affective effects. For instance, increases in schematic processing and simplified information processing can occur when anxiety is high. Indeed, such is consistent with related work on attentional bias in implicit memory. Additionally recent research has found that implicit racial evaluations (i.e. automatic prejudiced attitudes) can be amplified during intergroup interaction. Negative experiences have been illustrated in producing not only negative expectations, but also avoidant, or antagonistic, behavior such as hostility. Furthermore, when compared to anxiety levels and cognitive effort (e.g., impression management and self-presentation) in intragroup contexts, levels and depletion of resources may be exacerbated in the intergroup situation. Trait Anxiety can be either a short-term "state" or a long-term personality "trait." Trait anxiety reflects a stable tendency across the lifespan of responding with acute, state anxiety in the anticipation of threatening situations (whether they are actually deemed threatening or not). A meta-analysis showed that a high level of neuroticism is a risk factor for development of anxiety symptoms and disorders. Such anxiety may be conscious or unconscious. Personality can also be a trait leading to anxiety and depression. Through experience, many find it difficult to collect themselves due to their own personal nature. Choice or decision Anxiety induced by the need to choose between similar options is increasingly being recognized as a problem for individuals and for organizations. In 2004, Capgemini wrote: "Today we're all faced with greater choice, more competition and less time to consider our options or seek out the right advice." In a decision context, unpredictability or uncertainty may trigger emotional responses in anxious individuals that systematically alter decision-making. There are primarily two forms of this anxiety type.

In adults, an excessive fear of other people is not a developmentally common stage; it is called social anxiety. According to Cutting, social phobics do not fear the crowd but the fact that they may be judged negatively. Social anxiety varies in degree and severity. For some people, it is characterized by experiencing discomfort or awkwardness during physical social contact (e.g. embracing, shaking hands, etc. ), while in other cases it can lead to a fear of interacting with unfamiliar people altogether. Those suffering from this condition may restrict their lifestyles to accommodate the anxiety, minimizing social interaction whenever possible. Social anxiety also forms a core aspect of certain personality disorders, including avoidant personality disorder. To the extent that a person is fearful of social encounters with unfamiliar others, some people may experience anxiety particularly during interactions with outgroup members, or people who share different group memberships (i.e., by race, ethnicity, class, gender, etc.). Depending on the nature of the antecedent relations, cognitions, and situational factors, intergroup contact may be stressful and lead to feelings of anxiety. This apprehension or fear of contact with outgroup members is often called interracial or intergroup anxiety. As is the case with the more generalized forms of social anxiety, intergroup anxiety has behavioral, cognitive, and affective effects. For instance, increases in schematic processing and simplified information processing can occur when anxiety is high. Indeed, such is consistent with related work on attentional bias in implicit memory. Additionally recent research has found that implicit racial evaluations (i.e. automatic prejudiced attitudes) can be amplified during intergroup interaction. Negative experiences have been illustrated in producing not only negative expectations, but also avoidant, or antagonistic, behavior such as hostility. Furthermore, when compared to anxiety levels and cognitive effort (e.g., impression management and self-presentation) in intragroup contexts, levels and depletion of resources may be exacerbated in the intergroup situation. Trait Anxiety can be either a short-term "state" or a long-term personality "trait." Trait anxiety reflects a stable tendency across the lifespan of responding with acute, state anxiety in the anticipation of threatening situations (whether they are actually deemed threatening or not). A meta-analysis showed that a high level of neuroticism is a risk factor for development of anxiety symptoms and disorders. Such anxiety may be conscious or unconscious. Personality can also be a trait leading to anxiety and depression. Through experience, many find it difficult to collect themselves due to their own personal nature. Choice or decision Anxiety induced by the need to choose between similar options is increasingly being recognized as a problem for individuals and for organizations. In 2004, Capgemini wrote: "Today we're all faced with greater choice, more competition and less time to consider our options or seek out the right advice." In a decision context, unpredictability or uncertainty may trigger emotional responses in anxious individuals that systematically alter decision-making. There are primarily two forms of this anxiety type.

In adults, an excessive fear of other people is not a developmentally common stage; it is called social anxiety. According to Cutting, social phobics do not fear the crowd but the fact that they may be judged negatively. Social anxiety varies in degree and severity. For some people, it is characterized by experiencing discomfort or awkwardness during physical social contact (e.g. embracing, shaking hands, etc. ), while in other cases it can lead to a fear of interacting with unfamiliar people altogether. Those suffering from this condition may restrict their lifestyles to accommodate the anxiety, minimizing social interaction whenever possible. Social anxiety also forms a core aspect of certain personality disorders, including avoidant personality disorder. To the extent that a person is fearful of social encounters with unfamiliar others, some people may experience anxiety particularly during interactions with outgroup members, or people who share different group memberships (i.e., by race, ethnicity, class, gender, etc.). Depending on the nature of the antecedent relations, cognitions, and situational factors, intergroup contact may be stressful and lead to feelings of anxiety. This apprehension or fear of contact with outgroup members is often called interracial or intergroup anxiety. As is the case with the more generalized forms of social anxiety, intergroup anxiety has behavioral, cognitive, and affective effects. For instance, increases in schematic processing and simplified information processing can occur when anxiety is high. Indeed, such is consistent with related work on attentional bias in implicit memory. Additionally recent research has found that implicit racial evaluations (i.e. automatic prejudiced attitudes) can be amplified during intergroup interaction. Negative experiences have been illustrated in producing not only negative expectations, but also avoidant, or antagonistic, behavior such as hostility. Furthermore, when compared to anxiety levels and cognitive effort (e.g., impression management and self-presentation) in intragroup contexts, levels and depletion of resources may be exacerbated in the intergroup situation. Trait Anxiety can be either a short-term "state" or a long-term personality "trait." Trait anxiety reflects a stable tendency across the lifespan of responding with acute, state anxiety in the anticipation of threatening situations (whether they are actually deemed threatening or not). A meta-analysis showed that a high level of neuroticism is a risk factor for development of anxiety symptoms and disorders. Such anxiety may be conscious or unconscious. Personality can also be a trait leading to anxiety and depression. Through experience, many find it difficult to collect themselves due to their own personal nature. Choice or decision Anxiety induced by the need to choose between similar options is increasingly being recognized as a problem for individuals and for organizations. In 2004, Capgemini wrote: "Today we're all faced with greater choice, more competition and less time to consider our options or seek out the right advice." In a decision context, unpredictability or uncertainty may trigger emotional responses in anxious individuals that systematically alter decision-making. There are primarily two forms of this anxiety type.

The first form refers to a choice in which there are multiple potential outcomes with known or calculable probabilities. The second form refers to the uncertainty and ambiguity related to a decision context in which there are multiple possible outcomes with unknown probabilities. Panic disorder Panic disorder may share symptoms of stress and anxiety, but it is actually very different. Panic disorder is an anxiety disorder that occurs without any triggers. According to the U.S Department of Health and Human Services, this disorder can be distinguished by unexpected and repeated episodes of intense fear. Someone who suffers from panic disorder will eventually develop constant fear of another attack and as this progresses it will begin to affect daily functioning and an individual's general quality of life. It is reported by the Cleveland Clinic that panic disorder affects 2 to 3 percent of adult Americans and can begin around the time of the teenage and early adult years. Some symptoms include: difficulty breathing, chest pain, dizziness, trembling or shaking, feeling faint, nausea, fear that you are losing control or are about to die. Even though they suffer from these symptoms during an attack, the main symptom is the persistent fear of having future panic attacks. Anxiety disorders Anxiety disorders are a group of mental disorders characterized by exaggerated feelings of anxiety and fear responses. Anxiety is a worry about future events and fear is a reaction to current events. These feelings may cause physical symptoms, such as a fast heart rate and shakiness. There are a number of anxiety disorders: including generalized anxiety disorder, specific phobia, social anxiety disorder, separation anxiety disorder, agoraphobia, panic disorder, and selective mutism. The disorder differs by what results in the symptoms. People often have more than one anxiety disorder. Anxiety disorders are caused by a complex combination of genetic and environmental factors. To be diagnosed, symptoms typically need to be present for at least six months, be more than would be expected for the situation, and decrease a person's ability to function in their daily lives. Other problems that may result in similar symptoms include hyperthyroidism, heart disease, caffeine, alcohol, or cannabis use, and withdrawal from certain drugs, among others. Without treatment, anxiety disorders tend to remain. Treatment may include lifestyle changes, counselling, and medications. Counselling is typically with a type of cognitive behavioural therapy. Medications, such as antidepressants or beta blockers, may improve symptoms. About 12% of people are affected by an anxiety disorder in a given year and between 5–30% are affected at some point in their life. They occur about twice as often in women than they do in men, and generally begin before the age of 25. The most common are specific phobia which affects nearly 12% and social anxiety disorder which affects 10% at some point in their life. They affect those between the ages of 15 and 35 the most and become less common after the age of 55.

The first form refers to a choice in which there are multiple potential outcomes with known or calculable probabilities. The second form refers to the uncertainty and ambiguity related to a decision context in which there are multiple possible outcomes with unknown probabilities. Panic disorder Panic disorder may share symptoms of stress and anxiety, but it is actually very different. Panic disorder is an anxiety disorder that occurs without any triggers. According to the U.S Department of Health and Human Services, this disorder can be distinguished by unexpected and repeated episodes of intense fear. Someone who suffers from panic disorder will eventually develop constant fear of another attack and as this progresses it will begin to affect daily functioning and an individual's general quality of life. It is reported by the Cleveland Clinic that panic disorder affects 2 to 3 percent of adult Americans and can begin around the time of the teenage and early adult years. Some symptoms include: difficulty breathing, chest pain, dizziness, trembling or shaking, feeling faint, nausea, fear that you are losing control or are about to die. Even though they suffer from these symptoms during an attack, the main symptom is the persistent fear of having future panic attacks. Anxiety disorders Anxiety disorders are a group of mental disorders characterized by exaggerated feelings of anxiety and fear responses. Anxiety is a worry about future events and fear is a reaction to current events. These feelings may cause physical symptoms, such as a fast heart rate and shakiness. There are a number of anxiety disorders: including generalized anxiety disorder, specific phobia, social anxiety disorder, separation anxiety disorder, agoraphobia, panic disorder, and selective mutism. The disorder differs by what results in the symptoms. People often have more than one anxiety disorder. Anxiety disorders are caused by a complex combination of genetic and environmental factors. To be diagnosed, symptoms typically need to be present for at least six months, be more than would be expected for the situation, and decrease a person's ability to function in their daily lives. Other problems that may result in similar symptoms include hyperthyroidism, heart disease, caffeine, alcohol, or cannabis use, and withdrawal from certain drugs, among others. Without treatment, anxiety disorders tend to remain. Treatment may include lifestyle changes, counselling, and medications. Counselling is typically with a type of cognitive behavioural therapy. Medications, such as antidepressants or beta blockers, may improve symptoms. About 12% of people are affected by an anxiety disorder in a given year and between 5–30% are affected at some point in their life. They occur about twice as often in women than they do in men, and generally begin before the age of 25. The most common are specific phobia which affects nearly 12% and social anxiety disorder which affects 10% at some point in their life. They affect those between the ages of 15 and 35 the most and become less common after the age of 55.

The first form refers to a choice in which there are multiple potential outcomes with known or calculable probabilities. The second form refers to the uncertainty and ambiguity related to a decision context in which there are multiple possible outcomes with unknown probabilities. Panic disorder Panic disorder may share symptoms of stress and anxiety, but it is actually very different. Panic disorder is an anxiety disorder that occurs without any triggers. According to the U.S Department of Health and Human Services, this disorder can be distinguished by unexpected and repeated episodes of intense fear. Someone who suffers from panic disorder will eventually develop constant fear of another attack and as this progresses it will begin to affect daily functioning and an individual's general quality of life. It is reported by the Cleveland Clinic that panic disorder affects 2 to 3 percent of adult Americans and can begin around the time of the teenage and early adult years. Some symptoms include: difficulty breathing, chest pain, dizziness, trembling or shaking, feeling faint, nausea, fear that you are losing control or are about to die. Even though they suffer from these symptoms during an attack, the main symptom is the persistent fear of having future panic attacks. Anxiety disorders Anxiety disorders are a group of mental disorders characterized by exaggerated feelings of anxiety and fear responses. Anxiety is a worry about future events and fear is a reaction to current events. These feelings may cause physical symptoms, such as a fast heart rate and shakiness. There are a number of anxiety disorders: including generalized anxiety disorder, specific phobia, social anxiety disorder, separation anxiety disorder, agoraphobia, panic disorder, and selective mutism. The disorder differs by what results in the symptoms. People often have more than one anxiety disorder. Anxiety disorders are caused by a complex combination of genetic and environmental factors. To be diagnosed, symptoms typically need to be present for at least six months, be more than would be expected for the situation, and decrease a person's ability to function in their daily lives. Other problems that may result in similar symptoms include hyperthyroidism, heart disease, caffeine, alcohol, or cannabis use, and withdrawal from certain drugs, among others. Without treatment, anxiety disorders tend to remain. Treatment may include lifestyle changes, counselling, and medications. Counselling is typically with a type of cognitive behavioural therapy. Medications, such as antidepressants or beta blockers, may improve symptoms. About 12% of people are affected by an anxiety disorder in a given year and between 5–30% are affected at some point in their life. They occur about twice as often in women than they do in men, and generally begin before the age of 25. The most common are specific phobia which affects nearly 12% and social anxiety disorder which affects 10% at some point in their life. They affect those between the ages of 15 and 35 the most and become less common after the age of 55.

Rates appear to be higher in the United States and Europe. Short- and long-term anxiety Anxiety can be either a short-term "state" or a long-term "trait." Whereas trait anxiety represents worrying about future events, anxiety disorders are a group of mental disorders characterized by feelings of anxiety and fears. Four Ways to Be Anxious In his book Anxious: the modern mind in the age of anxiety Joseph LeDoux examines four experiences of anxiety through a brain-based lens: In the presence of an existing or imminent external threat, you worry about the event and its implications for your physical and/or psychological well-being. When a threat signal occurs, it signifies either that danger is present or near in space and time or that it might be coming in the future. Nonconscius threats processing by the brain activates defensive survival circuits, resulting in changes in information processing in the brain, controlled in part by increases in arousal and behavioral and physiological responses in the body that then produce signals that feed back to the brain and complement the physiological changes there, intensifying them and extending their duration. When you notice body sensations, you worry about what they might mean for your physical and/or psychological well-being. The trigger stimulus does not have to be an external stimulus but can be an internal one, as some people are particularly sensitive to body signals. Thoughts and memories may lead to you to worry about your physical and/or psychological well-being. We do not need to be presence of an external or internal stimulus to be anxious. An episodic memory of a past trauma or of a panic attack in the past is sufficient to activate the defence circuits. Thoughts and memories may result in existential dread, such as worry about leading a meaningful life or the eventuality of death. Examples are contemplations of whether one's life has been meaningful, the inevitability of death, or the difficulty of making decisions that have a moral value. These do not necessarily activate defensive systems; they are more or less pure forms of cognitive anxiety. Co-morbidity Anxiety disorders often occur with other mental health disorders, particularly major depressive disorder, bipolar disorder, eating disorders, or certain personality disorders. It also commonly occurs with personality traits such as neuroticism. This observed co-occurrence is partly due to genetic and environmental influences shared between these traits and anxiety. It is common for those with obsessive-compulsive disorder to experience anxiety. Anxiety is also commonly found in those who experience panic disorders, phobic anxiety disorders, severe stress, dissociative disorders, somatoform disorders, and some neurotic disorders. Risk factors Anxiety disorders are partly genetic, with twin studies suggesting 30-40% genetic influence on individual differences in anxiety. Environmental factors are also important. Twin studies show that individual-specific environments have a large influence on anxiety, whereas shared environmental influences (environments that affect twins in the same way) operate during childhood but decline through adolescence.

Rates appear to be higher in the United States and Europe. Short- and long-term anxiety Anxiety can be either a short-term "state" or a long-term "trait." Whereas trait anxiety represents worrying about future events, anxiety disorders are a group of mental disorders characterized by feelings of anxiety and fears. Four Ways to Be Anxious In his book Anxious: the modern mind in the age of anxiety Joseph LeDoux examines four experiences of anxiety through a brain-based lens: In the presence of an existing or imminent external threat, you worry about the event and its implications for your physical and/or psychological well-being. When a threat signal occurs, it signifies either that danger is present or near in space and time or that it might be coming in the future. Nonconscius threats processing by the brain activates defensive survival circuits, resulting in changes in information processing in the brain, controlled in part by increases in arousal and behavioral and physiological responses in the body that then produce signals that feed back to the brain and complement the physiological changes there, intensifying them and extending their duration. When you notice body sensations, you worry about what they might mean for your physical and/or psychological well-being. The trigger stimulus does not have to be an external stimulus but can be an internal one, as some people are particularly sensitive to body signals. Thoughts and memories may lead to you to worry about your physical and/or psychological well-being. We do not need to be presence of an external or internal stimulus to be anxious. An episodic memory of a past trauma or of a panic attack in the past is sufficient to activate the defence circuits. Thoughts and memories may result in existential dread, such as worry about leading a meaningful life or the eventuality of death. Examples are contemplations of whether one's life has been meaningful, the inevitability of death, or the difficulty of making decisions that have a moral value. These do not necessarily activate defensive systems; they are more or less pure forms of cognitive anxiety. Co-morbidity Anxiety disorders often occur with other mental health disorders, particularly major depressive disorder, bipolar disorder, eating disorders, or certain personality disorders. It also commonly occurs with personality traits such as neuroticism. This observed co-occurrence is partly due to genetic and environmental influences shared between these traits and anxiety. It is common for those with obsessive-compulsive disorder to experience anxiety. Anxiety is also commonly found in those who experience panic disorders, phobic anxiety disorders, severe stress, dissociative disorders, somatoform disorders, and some neurotic disorders. Risk factors Anxiety disorders are partly genetic, with twin studies suggesting 30-40% genetic influence on individual differences in anxiety. Environmental factors are also important. Twin studies show that individual-specific environments have a large influence on anxiety, whereas shared environmental influences (environments that affect twins in the same way) operate during childhood but decline through adolescence.

Rates appear to be higher in the United States and Europe. Short- and long-term anxiety Anxiety can be either a short-term "state" or a long-term "trait." Whereas trait anxiety represents worrying about future events, anxiety disorders are a group of mental disorders characterized by feelings of anxiety and fears. Four Ways to Be Anxious In his book Anxious: the modern mind in the age of anxiety Joseph LeDoux examines four experiences of anxiety through a brain-based lens: In the presence of an existing or imminent external threat, you worry about the event and its implications for your physical and/or psychological well-being. When a threat signal occurs, it signifies either that danger is present or near in space and time or that it might be coming in the future. Nonconscius threats processing by the brain activates defensive survival circuits, resulting in changes in information processing in the brain, controlled in part by increases in arousal and behavioral and physiological responses in the body that then produce signals that feed back to the brain and complement the physiological changes there, intensifying them and extending their duration. When you notice body sensations, you worry about what they might mean for your physical and/or psychological well-being. The trigger stimulus does not have to be an external stimulus but can be an internal one, as some people are particularly sensitive to body signals. Thoughts and memories may lead to you to worry about your physical and/or psychological well-being. We do not need to be presence of an external or internal stimulus to be anxious. An episodic memory of a past trauma or of a panic attack in the past is sufficient to activate the defence circuits. Thoughts and memories may result in existential dread, such as worry about leading a meaningful life or the eventuality of death. Examples are contemplations of whether one's life has been meaningful, the inevitability of death, or the difficulty of making decisions that have a moral value. These do not necessarily activate defensive systems; they are more or less pure forms of cognitive anxiety. Co-morbidity Anxiety disorders often occur with other mental health disorders, particularly major depressive disorder, bipolar disorder, eating disorders, or certain personality disorders. It also commonly occurs with personality traits such as neuroticism. This observed co-occurrence is partly due to genetic and environmental influences shared between these traits and anxiety. It is common for those with obsessive-compulsive disorder to experience anxiety. Anxiety is also commonly found in those who experience panic disorders, phobic anxiety disorders, severe stress, dissociative disorders, somatoform disorders, and some neurotic disorders. Risk factors Anxiety disorders are partly genetic, with twin studies suggesting 30-40% genetic influence on individual differences in anxiety. Environmental factors are also important. Twin studies show that individual-specific environments have a large influence on anxiety, whereas shared environmental influences (environments that affect twins in the same way) operate during childhood but decline through adolescence.

Specific measured ‘environments’ that have been associated with anxiety include child abuse, family history of mental health disorders, and poverty. Anxiety is also associated with drug use, including alcohol, caffeine, and benzodiazepines (which are often prescribed to treat anxiety). Neuroanatomy Neural circuitry involving the amygdala (which regulates emotions like anxiety and fear, stimulating the HPA axis and sympathetic nervous system) and hippocampus (which is implicated in emotional memory along with the amygdala) is thought to underlie anxiety. People who have anxiety tend to show high activity in response to emotional stimuli in the amygdala. Some writers believe that excessive anxiety can lead to an overpotentiation of the limbic system (which includes the amygdala and nucleus accumbens), giving increased future anxiety, but this does not appear to have been proven. Research upon adolescents who as infants had been highly apprehensive, vigilant, and fearful finds that their nucleus accumbens is more sensitive than that in other people when deciding to make an action that determined whether they received a reward. This suggests a link between circuits responsible for fear and also reward in anxious people. As researchers note, "a sense of 'responsibility', or self-agency, in a context of uncertainty (probabilistic outcomes) drives the neural system underlying appetitive motivation (i.e., nucleus accumbens) more strongly in temperamentally inhibited than noninhibited adolescents". The gut-brain axis The microbes of the gut can connect with the brain to affect anxiety. There are various pathways along which this communication can take place. One is through the major neurotransmitters. The gut microbes such as Bifidobacterium and Bacillus produce the neurotransmitters GABA and dopamine, respectively. The neurotransmitters signal to the nervous system of the gastrointestinal tract, and those signals will be carried to the brain through the vagus nerve or the spinal system. This is demonstrated by the fact that altering the microbiome has shown anxiety- and depression-reducing effects in mice, but not in subjects without vagus nerves. Another key pathway is the HPA axis, as mentioned above. The microbes can control the levels of cytokines in the body, and altering cytokine levels creates direct effects on areas of the brain such as the hypothalmus, the area that triggers HPA axis activity. The HPA axis regulates production of cortisol, a hormone that takes part in the body's stress response. When HPA activity spikes, cortisol levels increase, processing and reducing anxiety in stressful situations. These pathways, as well as the specific effects of individual taxa of microbes, are not yet completely clear, but the communication between the gut microbiome and the brain is undeniable, as is the ability of these pathways to alter anxiety levels. With this communication comes the potential to treat anxiety. Prebiotics and probiotics have been shown to reduced anxiety. For example, experiments in which mice were given fructo- and galacto-oligosaccharide prebiotics and Lactobacillus probiotics have both demonstrated a capability to reduce anxiety. In humans, results are not as concrete, but promising. Genetics Genetics and family history (e.g.

Specific measured ‘environments’ that have been associated with anxiety include child abuse, family history of mental health disorders, and poverty. Anxiety is also associated with drug use, including alcohol, caffeine, and benzodiazepines (which are often prescribed to treat anxiety). Neuroanatomy Neural circuitry involving the amygdala (which regulates emotions like anxiety and fear, stimulating the HPA axis and sympathetic nervous system) and hippocampus (which is implicated in emotional memory along with the amygdala) is thought to underlie anxiety. People who have anxiety tend to show high activity in response to emotional stimuli in the amygdala. Some writers believe that excessive anxiety can lead to an overpotentiation of the limbic system (which includes the amygdala and nucleus accumbens), giving increased future anxiety, but this does not appear to have been proven. Research upon adolescents who as infants had been highly apprehensive, vigilant, and fearful finds that their nucleus accumbens is more sensitive than that in other people when deciding to make an action that determined whether they received a reward. This suggests a link between circuits responsible for fear and also reward in anxious people. As researchers note, "a sense of 'responsibility', or self-agency, in a context of uncertainty (probabilistic outcomes) drives the neural system underlying appetitive motivation (i.e., nucleus accumbens) more strongly in temperamentally inhibited than noninhibited adolescents". The gut-brain axis The microbes of the gut can connect with the brain to affect anxiety. There are various pathways along which this communication can take place. One is through the major neurotransmitters. The gut microbes such as Bifidobacterium and Bacillus produce the neurotransmitters GABA and dopamine, respectively. The neurotransmitters signal to the nervous system of the gastrointestinal tract, and those signals will be carried to the brain through the vagus nerve or the spinal system. This is demonstrated by the fact that altering the microbiome has shown anxiety- and depression-reducing effects in mice, but not in subjects without vagus nerves. Another key pathway is the HPA axis, as mentioned above. The microbes can control the levels of cytokines in the body, and altering cytokine levels creates direct effects on areas of the brain such as the hypothalmus, the area that triggers HPA axis activity. The HPA axis regulates production of cortisol, a hormone that takes part in the body's stress response. When HPA activity spikes, cortisol levels increase, processing and reducing anxiety in stressful situations. These pathways, as well as the specific effects of individual taxa of microbes, are not yet completely clear, but the communication between the gut microbiome and the brain is undeniable, as is the ability of these pathways to alter anxiety levels. With this communication comes the potential to treat anxiety. Prebiotics and probiotics have been shown to reduced anxiety. For example, experiments in which mice were given fructo- and galacto-oligosaccharide prebiotics and Lactobacillus probiotics have both demonstrated a capability to reduce anxiety. In humans, results are not as concrete, but promising. Genetics Genetics and family history (e.g.

Specific measured ‘environments’ that have been associated with anxiety include child abuse, family history of mental health disorders, and poverty. Anxiety is also associated with drug use, including alcohol, caffeine, and benzodiazepines (which are often prescribed to treat anxiety). Neuroanatomy Neural circuitry involving the amygdala (which regulates emotions like anxiety and fear, stimulating the HPA axis and sympathetic nervous system) and hippocampus (which is implicated in emotional memory along with the amygdala) is thought to underlie anxiety. People who have anxiety tend to show high activity in response to emotional stimuli in the amygdala. Some writers believe that excessive anxiety can lead to an overpotentiation of the limbic system (which includes the amygdala and nucleus accumbens), giving increased future anxiety, but this does not appear to have been proven. Research upon adolescents who as infants had been highly apprehensive, vigilant, and fearful finds that their nucleus accumbens is more sensitive than that in other people when deciding to make an action that determined whether they received a reward. This suggests a link between circuits responsible for fear and also reward in anxious people. As researchers note, "a sense of 'responsibility', or self-agency, in a context of uncertainty (probabilistic outcomes) drives the neural system underlying appetitive motivation (i.e., nucleus accumbens) more strongly in temperamentally inhibited than noninhibited adolescents". The gut-brain axis The microbes of the gut can connect with the brain to affect anxiety. There are various pathways along which this communication can take place. One is through the major neurotransmitters. The gut microbes such as Bifidobacterium and Bacillus produce the neurotransmitters GABA and dopamine, respectively. The neurotransmitters signal to the nervous system of the gastrointestinal tract, and those signals will be carried to the brain through the vagus nerve or the spinal system. This is demonstrated by the fact that altering the microbiome has shown anxiety- and depression-reducing effects in mice, but not in subjects without vagus nerves. Another key pathway is the HPA axis, as mentioned above. The microbes can control the levels of cytokines in the body, and altering cytokine levels creates direct effects on areas of the brain such as the hypothalmus, the area that triggers HPA axis activity. The HPA axis regulates production of cortisol, a hormone that takes part in the body's stress response. When HPA activity spikes, cortisol levels increase, processing and reducing anxiety in stressful situations. These pathways, as well as the specific effects of individual taxa of microbes, are not yet completely clear, but the communication between the gut microbiome and the brain is undeniable, as is the ability of these pathways to alter anxiety levels. With this communication comes the potential to treat anxiety. Prebiotics and probiotics have been shown to reduced anxiety. For example, experiments in which mice were given fructo- and galacto-oligosaccharide prebiotics and Lactobacillus probiotics have both demonstrated a capability to reduce anxiety. In humans, results are not as concrete, but promising. Genetics Genetics and family history (e.g.

parental anxiety) may put an individual at increased risk of an anxiety disorder, but generally external stimuli will trigger its onset or exacerbation. Estimates of genetic influence on anxiety, based on studies of twins, range from 25 to 40% depending on the specific type and age-group under study. For example, genetic differences account for about 43% of variance in panic disorder and 28% in generalized anxiety disorder. Longitudinal twin studies have shown the moderate stability of anxiety from childhood through to adulthood is mainly influenced by stability in genetic influence. When investigating how anxiety is passed on from parents to children, it is important to account for sharing of genes as well as environments, for example using the intergenerational children-of-twins design. Many studies in the past used a candidate gene approach to test whether single genes were associated with anxiety. These investigations were based on hypotheses about how certain known genes influence neurotransmitters (such as serotonin and norepinephrine) and hormones (such as cortisol) that are implicated in anxiety. None of these findings are well replicated, with the possible exception of TMEM132D, COMT and MAO-A. The epigenetic signature of BDNF, a gene that codes for a protein called brain derived neurotrophic factor that is found in the brain, has also been associated with anxiety and specific patterns of neural activity. and a receptor gene for BDNF called NTRK2 was associated with anxiety in a large genome-wide investigation. The reason that most candidate gene findings have not replicated is that anxiety is a complex trait that is influenced by many genomic variants, each of which has a small effect on its own. Increasingly, studies of anxiety are using a hypothesis-free approach to look for parts of the genome that are implicated in anxiety using big enough samples to find associations with variants that have small effects. The largest explorations of the common genetic architecture of anxiety have been facilitated by the UK Biobank, the ANGST consortium and the CRC Fear, Anxiety and Anxiety Disorders. Medical conditions Many medical conditions can cause anxiety. This includes conditions that affect the ability to breathe, like COPD and asthma, and the difficulty in breathing that often occurs near death. Conditions that cause abdominal pain or chest pain can cause anxiety and may in some cases be a somatization of anxiety; the same is true for some sexual dysfunctions. Conditions that affect the face or the skin can cause social anxiety especially among adolescents, and developmental disabilities often lead to social anxiety for children as well. Life-threatening conditions like cancer also cause anxiety. Furthermore, certain organic diseases may present with anxiety or symptoms that mimic anxiety. These disorders include certain endocrine diseases (hypo- and hyperthyroidism, hyperprolactinemia), metabolic disorders (diabetes), deficiency states (low levels of vitamin D, B2, B12, folic acid), gastrointestinal diseases (celiac disease, non-celiac gluten sensitivity, inflammatory bowel disease), heart diseases, blood diseases (anemia), cerebral vascular accidents (transient ischemic attack, stroke), and brain degenerative diseases (Parkinson's disease, dementia, multiple sclerosis, Huntington's disease), among others.

parental anxiety) may put an individual at increased risk of an anxiety disorder, but generally external stimuli will trigger its onset or exacerbation. Estimates of genetic influence on anxiety, based on studies of twins, range from 25 to 40% depending on the specific type and age-group under study. For example, genetic differences account for about 43% of variance in panic disorder and 28% in generalized anxiety disorder. Longitudinal twin studies have shown the moderate stability of anxiety from childhood through to adulthood is mainly influenced by stability in genetic influence. When investigating how anxiety is passed on from parents to children, it is important to account for sharing of genes as well as environments, for example using the intergenerational children-of-twins design. Many studies in the past used a candidate gene approach to test whether single genes were associated with anxiety. These investigations were based on hypotheses about how certain known genes influence neurotransmitters (such as serotonin and norepinephrine) and hormones (such as cortisol) that are implicated in anxiety. None of these findings are well replicated, with the possible exception of TMEM132D, COMT and MAO-A. The epigenetic signature of BDNF, a gene that codes for a protein called brain derived neurotrophic factor that is found in the brain, has also been associated with anxiety and specific patterns of neural activity. and a receptor gene for BDNF called NTRK2 was associated with anxiety in a large genome-wide investigation. The reason that most candidate gene findings have not replicated is that anxiety is a complex trait that is influenced by many genomic variants, each of which has a small effect on its own. Increasingly, studies of anxiety are using a hypothesis-free approach to look for parts of the genome that are implicated in anxiety using big enough samples to find associations with variants that have small effects. The largest explorations of the common genetic architecture of anxiety have been facilitated by the UK Biobank, the ANGST consortium and the CRC Fear, Anxiety and Anxiety Disorders. Medical conditions Many medical conditions can cause anxiety. This includes conditions that affect the ability to breathe, like COPD and asthma, and the difficulty in breathing that often occurs near death. Conditions that cause abdominal pain or chest pain can cause anxiety and may in some cases be a somatization of anxiety; the same is true for some sexual dysfunctions. Conditions that affect the face or the skin can cause social anxiety especially among adolescents, and developmental disabilities often lead to social anxiety for children as well. Life-threatening conditions like cancer also cause anxiety. Furthermore, certain organic diseases may present with anxiety or symptoms that mimic anxiety. These disorders include certain endocrine diseases (hypo- and hyperthyroidism, hyperprolactinemia), metabolic disorders (diabetes), deficiency states (low levels of vitamin D, B2, B12, folic acid), gastrointestinal diseases (celiac disease, non-celiac gluten sensitivity, inflammatory bowel disease), heart diseases, blood diseases (anemia), cerebral vascular accidents (transient ischemic attack, stroke), and brain degenerative diseases (Parkinson's disease, dementia, multiple sclerosis, Huntington's disease), among others.

parental anxiety) may put an individual at increased risk of an anxiety disorder, but generally external stimuli will trigger its onset or exacerbation. Estimates of genetic influence on anxiety, based on studies of twins, range from 25 to 40% depending on the specific type and age-group under study. For example, genetic differences account for about 43% of variance in panic disorder and 28% in generalized anxiety disorder. Longitudinal twin studies have shown the moderate stability of anxiety from childhood through to adulthood is mainly influenced by stability in genetic influence. When investigating how anxiety is passed on from parents to children, it is important to account for sharing of genes as well as environments, for example using the intergenerational children-of-twins design. Many studies in the past used a candidate gene approach to test whether single genes were associated with anxiety. These investigations were based on hypotheses about how certain known genes influence neurotransmitters (such as serotonin and norepinephrine) and hormones (such as cortisol) that are implicated in anxiety. None of these findings are well replicated, with the possible exception of TMEM132D, COMT and MAO-A. The epigenetic signature of BDNF, a gene that codes for a protein called brain derived neurotrophic factor that is found in the brain, has also been associated with anxiety and specific patterns of neural activity. and a receptor gene for BDNF called NTRK2 was associated with anxiety in a large genome-wide investigation. The reason that most candidate gene findings have not replicated is that anxiety is a complex trait that is influenced by many genomic variants, each of which has a small effect on its own. Increasingly, studies of anxiety are using a hypothesis-free approach to look for parts of the genome that are implicated in anxiety using big enough samples to find associations with variants that have small effects. The largest explorations of the common genetic architecture of anxiety have been facilitated by the UK Biobank, the ANGST consortium and the CRC Fear, Anxiety and Anxiety Disorders. Medical conditions Many medical conditions can cause anxiety. This includes conditions that affect the ability to breathe, like COPD and asthma, and the difficulty in breathing that often occurs near death. Conditions that cause abdominal pain or chest pain can cause anxiety and may in some cases be a somatization of anxiety; the same is true for some sexual dysfunctions. Conditions that affect the face or the skin can cause social anxiety especially among adolescents, and developmental disabilities often lead to social anxiety for children as well. Life-threatening conditions like cancer also cause anxiety. Furthermore, certain organic diseases may present with anxiety or symptoms that mimic anxiety. These disorders include certain endocrine diseases (hypo- and hyperthyroidism, hyperprolactinemia), metabolic disorders (diabetes), deficiency states (low levels of vitamin D, B2, B12, folic acid), gastrointestinal diseases (celiac disease, non-celiac gluten sensitivity, inflammatory bowel disease), heart diseases, blood diseases (anemia), cerebral vascular accidents (transient ischemic attack, stroke), and brain degenerative diseases (Parkinson's disease, dementia, multiple sclerosis, Huntington's disease), among others.

Substance-induced Several drugs can cause or worsen anxiety, whether in intoxication, withdrawal or as side effect. These include alcohol, tobacco, sedatives (including prescription benzodiazepines), opioids (including prescription pain killers and illicit drugs like heroin), stimulants (such as caffeine, cocaine and amphetamines), hallucinogens, and inhalants. While many often report self-medicating anxiety with these substances, improvements in anxiety from drugs are usually short-lived (with worsening of anxiety in the long term, sometimes with acute anxiety as soon as the drug effects wear off) and tend to be exaggerated. Acute exposure to toxic levels of benzene may cause euphoria, anxiety, and irritability lasting up to 2 weeks after the exposure. Psychological Poor coping skills (e.g., rigidity/inflexible problem solving, denial, avoidance, impulsivity, extreme self-expectation, negative thoughts, affective instability, and inability to focus on problems) are associated with anxiety. Anxiety is also linked and perpetuated by the person's own pessimistic outcome expectancy and how they cope with feedback negativity. Temperament (e.g., neuroticism) and attitudes (e.g. pessimism) have been found to be risk factors for anxiety. Cognitive distortions such as overgeneralizing, catastrophizing, mind reading, emotional reasoning, binocular trick, and mental filter can result in anxiety. For example, an overgeneralized belief that something bad "always" happens may lead someone to have excessive fears of even minimally risky situations and to avoid benign social situations due to anticipatory anxiety of embarrassment. In addition, those who have high anxiety can also create future stressful life events. Together, these findings suggest that anxious thoughts can lead to anticipatory anxiety as well as stressful events, which in turn cause more anxiety. Such unhealthy thoughts can be targets for successful treatment with cognitive therapy. Psychodynamic theory posits that anxiety is often the result of opposing unconscious wishes or fears that manifest via maladaptive defense mechanisms (such as suppression, repression, anticipation, regression, somatization, passive aggression, dissociation) that develop to adapt to problems with early objects (e.g., caregivers) and empathic failures in childhood. For example, persistent parental discouragement of anger may result in repression/suppression of angry feelings which manifests as gastrointestinal distress (somatization) when provoked by another while the anger remains unconscious and outside the individual's awareness. Such conflicts can be targets for successful treatment with psychodynamic therapy. While psychodynamic therapy tends to explore the underlying roots of anxiety, cognitive behavioral therapy has also been shown to be a successful treatment for anxiety by altering irrational thoughts and unwanted behaviors. Evolutionary psychology An evolutionary psychology explanation is that increased anxiety serves the purpose of increased vigilance regarding potential threats in the environment as well as increased tendency to take proactive actions regarding such possible threats. This may cause false positive reactions but an individual suffering from anxiety may also avoid real threats. This may explain why anxious people are less likely to die due to accidents. There is ample empirical evidence that anxiety can have adaptive value. Within a school, timid fish are more likely than bold fish to survive a predator.

Substance-induced Several drugs can cause or worsen anxiety, whether in intoxication, withdrawal or as side effect. These include alcohol, tobacco, sedatives (including prescription benzodiazepines), opioids (including prescription pain killers and illicit drugs like heroin), stimulants (such as caffeine, cocaine and amphetamines), hallucinogens, and inhalants. While many often report self-medicating anxiety with these substances, improvements in anxiety from drugs are usually short-lived (with worsening of anxiety in the long term, sometimes with acute anxiety as soon as the drug effects wear off) and tend to be exaggerated. Acute exposure to toxic levels of benzene may cause euphoria, anxiety, and irritability lasting up to 2 weeks after the exposure. Psychological Poor coping skills (e.g., rigidity/inflexible problem solving, denial, avoidance, impulsivity, extreme self-expectation, negative thoughts, affective instability, and inability to focus on problems) are associated with anxiety. Anxiety is also linked and perpetuated by the person's own pessimistic outcome expectancy and how they cope with feedback negativity. Temperament (e.g., neuroticism) and attitudes (e.g. pessimism) have been found to be risk factors for anxiety. Cognitive distortions such as overgeneralizing, catastrophizing, mind reading, emotional reasoning, binocular trick, and mental filter can result in anxiety. For example, an overgeneralized belief that something bad "always" happens may lead someone to have excessive fears of even minimally risky situations and to avoid benign social situations due to anticipatory anxiety of embarrassment. In addition, those who have high anxiety can also create future stressful life events. Together, these findings suggest that anxious thoughts can lead to anticipatory anxiety as well as stressful events, which in turn cause more anxiety. Such unhealthy thoughts can be targets for successful treatment with cognitive therapy. Psychodynamic theory posits that anxiety is often the result of opposing unconscious wishes or fears that manifest via maladaptive defense mechanisms (such as suppression, repression, anticipation, regression, somatization, passive aggression, dissociation) that develop to adapt to problems with early objects (e.g., caregivers) and empathic failures in childhood. For example, persistent parental discouragement of anger may result in repression/suppression of angry feelings which manifests as gastrointestinal distress (somatization) when provoked by another while the anger remains unconscious and outside the individual's awareness. Such conflicts can be targets for successful treatment with psychodynamic therapy. While psychodynamic therapy tends to explore the underlying roots of anxiety, cognitive behavioral therapy has also been shown to be a successful treatment for anxiety by altering irrational thoughts and unwanted behaviors. Evolutionary psychology An evolutionary psychology explanation is that increased anxiety serves the purpose of increased vigilance regarding potential threats in the environment as well as increased tendency to take proactive actions regarding such possible threats. This may cause false positive reactions but an individual suffering from anxiety may also avoid real threats. This may explain why anxious people are less likely to die due to accidents. There is ample empirical evidence that anxiety can have adaptive value. Within a school, timid fish are more likely than bold fish to survive a predator.

Substance-induced Several drugs can cause or worsen anxiety, whether in intoxication, withdrawal or as side effect. These include alcohol, tobacco, sedatives (including prescription benzodiazepines), opioids (including prescription pain killers and illicit drugs like heroin), stimulants (such as caffeine, cocaine and amphetamines), hallucinogens, and inhalants. While many often report self-medicating anxiety with these substances, improvements in anxiety from drugs are usually short-lived (with worsening of anxiety in the long term, sometimes with acute anxiety as soon as the drug effects wear off) and tend to be exaggerated. Acute exposure to toxic levels of benzene may cause euphoria, anxiety, and irritability lasting up to 2 weeks after the exposure. Psychological Poor coping skills (e.g., rigidity/inflexible problem solving, denial, avoidance, impulsivity, extreme self-expectation, negative thoughts, affective instability, and inability to focus on problems) are associated with anxiety. Anxiety is also linked and perpetuated by the person's own pessimistic outcome expectancy and how they cope with feedback negativity. Temperament (e.g., neuroticism) and attitudes (e.g. pessimism) have been found to be risk factors for anxiety. Cognitive distortions such as overgeneralizing, catastrophizing, mind reading, emotional reasoning, binocular trick, and mental filter can result in anxiety. For example, an overgeneralized belief that something bad "always" happens may lead someone to have excessive fears of even minimally risky situations and to avoid benign social situations due to anticipatory anxiety of embarrassment. In addition, those who have high anxiety can also create future stressful life events. Together, these findings suggest that anxious thoughts can lead to anticipatory anxiety as well as stressful events, which in turn cause more anxiety. Such unhealthy thoughts can be targets for successful treatment with cognitive therapy. Psychodynamic theory posits that anxiety is often the result of opposing unconscious wishes or fears that manifest via maladaptive defense mechanisms (such as suppression, repression, anticipation, regression, somatization, passive aggression, dissociation) that develop to adapt to problems with early objects (e.g., caregivers) and empathic failures in childhood. For example, persistent parental discouragement of anger may result in repression/suppression of angry feelings which manifests as gastrointestinal distress (somatization) when provoked by another while the anger remains unconscious and outside the individual's awareness. Such conflicts can be targets for successful treatment with psychodynamic therapy. While psychodynamic therapy tends to explore the underlying roots of anxiety, cognitive behavioral therapy has also been shown to be a successful treatment for anxiety by altering irrational thoughts and unwanted behaviors. Evolutionary psychology An evolutionary psychology explanation is that increased anxiety serves the purpose of increased vigilance regarding potential threats in the environment as well as increased tendency to take proactive actions regarding such possible threats. This may cause false positive reactions but an individual suffering from anxiety may also avoid real threats. This may explain why anxious people are less likely to die due to accidents. There is ample empirical evidence that anxiety can have adaptive value. Within a school, timid fish are more likely than bold fish to survive a predator.

When people are confronted with unpleasant and potentially harmful stimuli such as foul odors or tastes, PET-scans show increased blood flow in the amygdala. In these studies, the participants also reported moderate anxiety. This might indicate that anxiety is a protective mechanism designed to prevent the organism from engaging in potentially harmful behaviors. Social Social risk factors for anxiety include a history of trauma (e.g., physical, sexual or emotional abuse or assault), bullying, early life experiences and parenting factors (e.g., rejection, lack of warmth, high hostility, harsh discipline, high parental negative affect, anxious childrearing, modelling of dysfunctional and drug-abusing behaviour, discouragement of emotions, poor socialization, poor attachment, and child abuse and neglect), cultural factors (e.g., stoic families/cultures, persecuted minorities including the disabled), and socioeconomics (e.g., uneducated, unemployed, impoverished although developed countries have higher rates of anxiety disorders than developing countries). A 2019 comprehensive systematic review of over 50 studies showed that food insecurity in the United States is strongly associated with depression, anxiety, and sleep disorders. Food-insecure individuals had an almost 3 fold risk increase of testing positive for anxiety when compared to food-secure individuals. Gender socialization Contextual factors that are thought to contribute to anxiety include gender socialization and learning experiences. In particular, learning mastery (the degree to which people perceive their lives to be under their own control) and instrumentality, which includes such traits as self-confidence, self-efficacy, independence, and competitiveness fully mediate the relation between gender and anxiety. That is, though gender differences in anxiety exist, with higher levels of anxiety in women compared to men, gender socialization and learning mastery explain these gender differences. Treatment The first step in the management of a person with anxiety symptoms involves evaluating the possible presence of an underlying medical cause, the recognition of which is essential in order to decide the correct treatment. Anxiety symptoms may mask an organic disease, or appear associated with or as a result of a medical disorder. Cognitive behavioral therapy (CBT) is effective for anxiety disorders and is a first line treatment. CBT appears to be equally effective when carried out via the internet. While evidence for mental health apps is promising, it is preliminary. Psychopharmacological treatment can be used in parallel to CBT or can be used alone. As a general rule, most anxiety disorders respond well to first-line agents. Such drugs, also used as anti-depressants, are the selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors, that work by blocking the reuptake of specific neurotransmitters and resulting in the increase in availability of these neurotransmitters. Additionally, benzodiazepines are often prescribed to individuals with anxiety disorder. Benzodiazepines produce an anxiolytic response by modulating GABA and increasing its receptor binding. A third common treatment involves a category of drug known as serotonin agonists. This category of drug works by initiating a physiological response at 5-HT1A receptor by increasing the action of serotonin at this receptor. Other treatment options include pregabalin, tricyclic antidepressants, and moclobemide, among others. Prevention The above risk factors give natural avenues for prevention.

When people are confronted with unpleasant and potentially harmful stimuli such as foul odors or tastes, PET-scans show increased blood flow in the amygdala. In these studies, the participants also reported moderate anxiety. This might indicate that anxiety is a protective mechanism designed to prevent the organism from engaging in potentially harmful behaviors. Social Social risk factors for anxiety include a history of trauma (e.g., physical, sexual or emotional abuse or assault), bullying, early life experiences and parenting factors (e.g., rejection, lack of warmth, high hostility, harsh discipline, high parental negative affect, anxious childrearing, modelling of dysfunctional and drug-abusing behaviour, discouragement of emotions, poor socialization, poor attachment, and child abuse and neglect), cultural factors (e.g., stoic families/cultures, persecuted minorities including the disabled), and socioeconomics (e.g., uneducated, unemployed, impoverished although developed countries have higher rates of anxiety disorders than developing countries). A 2019 comprehensive systematic review of over 50 studies showed that food insecurity in the United States is strongly associated with depression, anxiety, and sleep disorders. Food-insecure individuals had an almost 3 fold risk increase of testing positive for anxiety when compared to food-secure individuals. Gender socialization Contextual factors that are thought to contribute to anxiety include gender socialization and learning experiences. In particular, learning mastery (the degree to which people perceive their lives to be under their own control) and instrumentality, which includes such traits as self-confidence, self-efficacy, independence, and competitiveness fully mediate the relation between gender and anxiety. That is, though gender differences in anxiety exist, with higher levels of anxiety in women compared to men, gender socialization and learning mastery explain these gender differences. Treatment The first step in the management of a person with anxiety symptoms involves evaluating the possible presence of an underlying medical cause, the recognition of which is essential in order to decide the correct treatment. Anxiety symptoms may mask an organic disease, or appear associated with or as a result of a medical disorder. Cognitive behavioral therapy (CBT) is effective for anxiety disorders and is a first line treatment. CBT appears to be equally effective when carried out via the internet. While evidence for mental health apps is promising, it is preliminary. Psychopharmacological treatment can be used in parallel to CBT or can be used alone. As a general rule, most anxiety disorders respond well to first-line agents. Such drugs, also used as anti-depressants, are the selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors, that work by blocking the reuptake of specific neurotransmitters and resulting in the increase in availability of these neurotransmitters. Additionally, benzodiazepines are often prescribed to individuals with anxiety disorder. Benzodiazepines produce an anxiolytic response by modulating GABA and increasing its receptor binding. A third common treatment involves a category of drug known as serotonin agonists. This category of drug works by initiating a physiological response at 5-HT1A receptor by increasing the action of serotonin at this receptor. Other treatment options include pregabalin, tricyclic antidepressants, and moclobemide, among others. Prevention The above risk factors give natural avenues for prevention.

When people are confronted with unpleasant and potentially harmful stimuli such as foul odors or tastes, PET-scans show increased blood flow in the amygdala. In these studies, the participants also reported moderate anxiety. This might indicate that anxiety is a protective mechanism designed to prevent the organism from engaging in potentially harmful behaviors. Social Social risk factors for anxiety include a history of trauma (e.g., physical, sexual or emotional abuse or assault), bullying, early life experiences and parenting factors (e.g., rejection, lack of warmth, high hostility, harsh discipline, high parental negative affect, anxious childrearing, modelling of dysfunctional and drug-abusing behaviour, discouragement of emotions, poor socialization, poor attachment, and child abuse and neglect), cultural factors (e.g., stoic families/cultures, persecuted minorities including the disabled), and socioeconomics (e.g., uneducated, unemployed, impoverished although developed countries have higher rates of anxiety disorders than developing countries). A 2019 comprehensive systematic review of over 50 studies showed that food insecurity in the United States is strongly associated with depression, anxiety, and sleep disorders. Food-insecure individuals had an almost 3 fold risk increase of testing positive for anxiety when compared to food-secure individuals. Gender socialization Contextual factors that are thought to contribute to anxiety include gender socialization and learning experiences. In particular, learning mastery (the degree to which people perceive their lives to be under their own control) and instrumentality, which includes such traits as self-confidence, self-efficacy, independence, and competitiveness fully mediate the relation between gender and anxiety. That is, though gender differences in anxiety exist, with higher levels of anxiety in women compared to men, gender socialization and learning mastery explain these gender differences. Treatment The first step in the management of a person with anxiety symptoms involves evaluating the possible presence of an underlying medical cause, the recognition of which is essential in order to decide the correct treatment. Anxiety symptoms may mask an organic disease, or appear associated with or as a result of a medical disorder. Cognitive behavioral therapy (CBT) is effective for anxiety disorders and is a first line treatment. CBT appears to be equally effective when carried out via the internet. While evidence for mental health apps is promising, it is preliminary. Psychopharmacological treatment can be used in parallel to CBT or can be used alone. As a general rule, most anxiety disorders respond well to first-line agents. Such drugs, also used as anti-depressants, are the selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors, that work by blocking the reuptake of specific neurotransmitters and resulting in the increase in availability of these neurotransmitters. Additionally, benzodiazepines are often prescribed to individuals with anxiety disorder. Benzodiazepines produce an anxiolytic response by modulating GABA and increasing its receptor binding. A third common treatment involves a category of drug known as serotonin agonists. This category of drug works by initiating a physiological response at 5-HT1A receptor by increasing the action of serotonin at this receptor. Other treatment options include pregabalin, tricyclic antidepressants, and moclobemide, among others. Prevention The above risk factors give natural avenues for prevention.

A 2017 review found that psychological or educational interventions have a small yet statistically significant benefit for the prevention of anxiety in varied population types. Pathophysiology Anxiety disorder appears to be a genetically inherited neurochemical dysfunction that may involve autonomic imbalance; decreased GABA-ergic tone; allelic polymorphism of the catechol-O-methyltransferase (COMT) gene; increased adenosine receptor function; increased cortisol. In the central nervous system (CNS), the major mediators of the symptoms of anxiety disorders appear to be norepinephrine, serotonin, dopamine, and gamma-aminobutyric acid (GABA). Other neurotransmitters and peptides, such as corticotropin-releasing factor, may be involved. Peripherally, the autonomic nervous system, especially the sympathetic nervous system, mediates many of the symptoms. Increased flow in the right parahippocampal region and reduced serotonin type 1A receptor binding in the anterior and posterior cingulate and raphe of patients are the diagnostic factors for prevalence of anxiety disorder. The amygdala is central to the processing of fear and anxiety, and its function may be disrupted in anxiety disorders. Anxiety processing in the basolateral amygdala has been implicated with expansion of dendritic arborization of the amygdaloid neurons. SK2 potassium channels mediate inhibitory influence on action potentials and reduce arborization. See also List of people with an anxiety disorder References External links Emotions

A 2017 review found that psychological or educational interventions have a small yet statistically significant benefit for the prevention of anxiety in varied population types. Pathophysiology Anxiety disorder appears to be a genetically inherited neurochemical dysfunction that may involve autonomic imbalance; decreased GABA-ergic tone; allelic polymorphism of the catechol-O-methyltransferase (COMT) gene; increased adenosine receptor function; increased cortisol. In the central nervous system (CNS), the major mediators of the symptoms of anxiety disorders appear to be norepinephrine, serotonin, dopamine, and gamma-aminobutyric acid (GABA). Other neurotransmitters and peptides, such as corticotropin-releasing factor, may be involved. Peripherally, the autonomic nervous system, especially the sympathetic nervous system, mediates many of the symptoms. Increased flow in the right parahippocampal region and reduced serotonin type 1A receptor binding in the anterior and posterior cingulate and raphe of patients are the diagnostic factors for prevalence of anxiety disorder. The amygdala is central to the processing of fear and anxiety, and its function may be disrupted in anxiety disorders. Anxiety processing in the basolateral amygdala has been implicated with expansion of dendritic arborization of the amygdaloid neurons. SK2 potassium channels mediate inhibitory influence on action potentials and reduce arborization. See also List of people with an anxiety disorder References External links Emotions

A 2017 review found that psychological or educational interventions have a small yet statistically significant benefit for the prevention of anxiety in varied population types. Pathophysiology Anxiety disorder appears to be a genetically inherited neurochemical dysfunction that may involve autonomic imbalance; decreased GABA-ergic tone; allelic polymorphism of the catechol-O-methyltransferase (COMT) gene; increased adenosine receptor function; increased cortisol. In the central nervous system (CNS), the major mediators of the symptoms of anxiety disorders appear to be norepinephrine, serotonin, dopamine, and gamma-aminobutyric acid (GABA). Other neurotransmitters and peptides, such as corticotropin-releasing factor, may be involved. Peripherally, the autonomic nervous system, especially the sympathetic nervous system, mediates many of the symptoms. Increased flow in the right parahippocampal region and reduced serotonin type 1A receptor binding in the anterior and posterior cingulate and raphe of patients are the diagnostic factors for prevalence of anxiety disorder. The amygdala is central to the processing of fear and anxiety, and its function may be disrupted in anxiety disorders. Anxiety processing in the basolateral amygdala has been implicated with expansion of dendritic arborization of the amygdaloid neurons. SK2 potassium channels mediate inhibitory influence on action potentials and reduce arborization. See also List of people with an anxiety disorder References External links Emotions

A. A. Milne Alan Alexander Milne (; 18 January 1882 – 31 January 1956) was an English author, best known for his books about the teddy bear Winnie-the-Pooh and for various poems. Milne was a noted writer, primarily as a playwright, before the huge success of Pooh overshadowed all his previous work. Milne served in both World Wars, joining the British Army in World War I, and as a captain of the British Home Guard in World War II. He was the father of bookseller Christopher Robin Milne, upon whom the character Christopher Robin is based. Early life and military career Alan Alexander Milne was born in Kilburn, London, to John Vine Milne, who was born in England, and Sarah Marie Milne (née Heginbotham). He grew up at Henley House School, 6/7 Mortimer Road (now Crescent), Kilburn, a small independent school run by his father. One of his teachers was H. G. Wells, who taught there in 1889–90. Milne attended Westminster School and Trinity College, Cambridge, where he studied on a mathematics scholarship, graduating with a B.A. in Mathematics in 1903. He edited and wrote for Granta, a student magazine. He collaborated with his brother Kenneth and their articles appeared over the initials AKM. Milne's work came to the attention of the leading British humour magazine Punch, where Milne was to become a contributor and later an assistant editor. Considered a talented cricket fielder, Milne played for two amateur teams that were largely composed of British writers: the Allahakbarries and the Authors XI. His teammates included fellow writers J. M. Barrie, Arthur Conan Doyle and P. G. Wodehouse. Milne joined the British Army in World War I and served as an officer in the Royal Warwickshire Regiment and later, after a debilitating illness, the Royal Corps of Signals. He was commissioned into the 4th Battalion, Royal Warwickshire Regiment, on 1 February 1915 as a second lieutenant (on probation). His commission was confirmed on 20 December 1915. On 7 July 1916, he was injured in the Battle of the Somme and invalided back to England. Having recuperated, he was recruited into Military Intelligence to write propaganda articles for MI7 (b) between 1916 and 1918. He was discharged on 14 February 1919, and settled in Mallord Street, Chelsea. He relinquished his commission on 19 February 1920, retaining the rank of lieutenant. After the war, he wrote a denunciation of war titled Peace with Honour (1934), which he retracted somewhat with 1940's War with Honour. During World War II, Milne was one of the most prominent critics of fellow English writer (and Authors XI cricket teammate) P. G. Wodehouse, who was captured at his country home in France by the Nazis and imprisoned for a year. Wodehouse made radio broadcasts about his internment, which were broadcast from Berlin. Although the light-hearted broadcasts made fun of the Germans, Milne accused Wodehouse of committing an act of near treason by cooperating with his country's enemy. Wodehouse got some revenge on his former friend (e.g.

A. A. Milne Alan Alexander Milne (; 18 January 1882 – 31 January 1956) was an English author, best known for his books about the teddy bear Winnie-the-Pooh and for various poems. Milne was a noted writer, primarily as a playwright, before the huge success of Pooh overshadowed all his previous work. Milne served in both World Wars, joining the British Army in World War I, and as a captain of the British Home Guard in World War II. He was the father of bookseller Christopher Robin Milne, upon whom the character Christopher Robin is based. Early life and military career Alan Alexander Milne was born in Kilburn, London, to John Vine Milne, who was born in England, and Sarah Marie Milne (née Heginbotham). He grew up at Henley House School, 6/7 Mortimer Road (now Crescent), Kilburn, a small independent school run by his father. One of his teachers was H. G. Wells, who taught there in 1889–90. Milne attended Westminster School and Trinity College, Cambridge, where he studied on a mathematics scholarship, graduating with a B.A. in Mathematics in 1903. He edited and wrote for Granta, a student magazine. He collaborated with his brother Kenneth and their articles appeared over the initials AKM. Milne's work came to the attention of the leading British humour magazine Punch, where Milne was to become a contributor and later an assistant editor. Considered a talented cricket fielder, Milne played for two amateur teams that were largely composed of British writers: the Allahakbarries and the Authors XI. His teammates included fellow writers J. M. Barrie, Arthur Conan Doyle and P. G. Wodehouse. Milne joined the British Army in World War I and served as an officer in the Royal Warwickshire Regiment and later, after a debilitating illness, the Royal Corps of Signals. He was commissioned into the 4th Battalion, Royal Warwickshire Regiment, on 1 February 1915 as a second lieutenant (on probation). His commission was confirmed on 20 December 1915. On 7 July 1916, he was injured in the Battle of the Somme and invalided back to England. Having recuperated, he was recruited into Military Intelligence to write propaganda articles for MI7 (b) between 1916 and 1918. He was discharged on 14 February 1919, and settled in Mallord Street, Chelsea. He relinquished his commission on 19 February 1920, retaining the rank of lieutenant. After the war, he wrote a denunciation of war titled Peace with Honour (1934), which he retracted somewhat with 1940's War with Honour. During World War II, Milne was one of the most prominent critics of fellow English writer (and Authors XI cricket teammate) P. G. Wodehouse, who was captured at his country home in France by the Nazis and imprisoned for a year. Wodehouse made radio broadcasts about his internment, which were broadcast from Berlin. Although the light-hearted broadcasts made fun of the Germans, Milne accused Wodehouse of committing an act of near treason by cooperating with his country's enemy. Wodehouse got some revenge on his former friend (e.g.

in The Mating Season) by creating fatuous parodies of the Christopher Robin poems in some of his later stories, and claiming that Milne "was probably jealous of all other writers.... But I loved his stuff." Milne married Dorothy "Daphne" de Sélincourt (1890–1971) in 1913 and their son Christopher Robin Milne was born in 1920. In 1925, Milne bought a country home, Cotchford Farm, in Hartfield, East Sussex. During World War II, Milne was a captain in the British Home Guard in Hartfield & Forest Row, insisting on being plain "Mr. Milne" to the members of his platoon. He retired to the farm after a stroke and brain surgery in 1952 left him an invalid, and by August 1953, "he seemed very old and disenchanted." Milne died in January 1956, aged 74. Literary career 1903 to 1925 After graduating from Cambridge University in 1903, A. A. Milne contributed humorous verse and whimsical essays to Punch, joining the staff in 1906 and becoming an assistant editor. During this period he published 18 plays and three novels, including the murder mystery The Red House Mystery (1922). His son was born in August 1920 and in 1924 Milne produced a collection of children's poems, When We Were Very Young, which were illustrated by Punch staff cartoonist E. H. Shepard. A collection of short stories for children A Gallery of Children, and other stories that became part of the Winnie-the-Pooh books, were first published in 1925. Milne was an early screenwriter for the nascent British film industry, writing four stories filmed in 1920 for the company Minerva Films (founded in 1920 by the actor Leslie Howard and his friend and story editor Adrian Brunel). These were The Bump, starring Aubrey Smith; Twice Two; Five Pound Reward; and Bookworms. Some of these films survive in the archives of the British Film Institute. Milne had met Howard when the actor starred in Milne's play Mr Pim Passes By in London. Looking back on this period (in 1926), Milne observed that when he told his agent that he was going to write a detective story, he was told that what the country wanted from a "Punch humorist" was a humorous story; when two years later he said he was writing nursery rhymes, his agent and publisher were convinced he should write another detective story; and after another two years, he was being told that writing a detective story would be in the worst of taste given the demand for children's books. He concluded that "the only excuse which I have yet discovered for writing anything is that I want to write it; and I should be as proud to be delivered of a Telephone Directory con amore as I should be ashamed to create a Blank Verse Tragedy at the bidding of others."

in The Mating Season) by creating fatuous parodies of the Christopher Robin poems in some of his later stories, and claiming that Milne "was probably jealous of all other writers.... But I loved his stuff." Milne married Dorothy "Daphne" de Sélincourt (1890–1971) in 1913 and their son Christopher Robin Milne was born in 1920. In 1925, Milne bought a country home, Cotchford Farm, in Hartfield, East Sussex. During World War II, Milne was a captain in the British Home Guard in Hartfield & Forest Row, insisting on being plain "Mr. Milne" to the members of his platoon. He retired to the farm after a stroke and brain surgery in 1952 left him an invalid, and by August 1953, "he seemed very old and disenchanted." Milne died in January 1956, aged 74. Literary career 1903 to 1925 After graduating from Cambridge University in 1903, A. A. Milne contributed humorous verse and whimsical essays to Punch, joining the staff in 1906 and becoming an assistant editor. During this period he published 18 plays and three novels, including the murder mystery The Red House Mystery (1922). His son was born in August 1920 and in 1924 Milne produced a collection of children's poems, When We Were Very Young, which were illustrated by Punch staff cartoonist E. H. Shepard. A collection of short stories for children A Gallery of Children, and other stories that became part of the Winnie-the-Pooh books, were first published in 1925. Milne was an early screenwriter for the nascent British film industry, writing four stories filmed in 1920 for the company Minerva Films (founded in 1920 by the actor Leslie Howard and his friend and story editor Adrian Brunel). These were The Bump, starring Aubrey Smith; Twice Two; Five Pound Reward; and Bookworms. Some of these films survive in the archives of the British Film Institute. Milne had met Howard when the actor starred in Milne's play Mr Pim Passes By in London. Looking back on this period (in 1926), Milne observed that when he told his agent that he was going to write a detective story, he was told that what the country wanted from a "Punch humorist" was a humorous story; when two years later he said he was writing nursery rhymes, his agent and publisher were convinced he should write another detective story; and after another two years, he was being told that writing a detective story would be in the worst of taste given the demand for children's books. He concluded that "the only excuse which I have yet discovered for writing anything is that I want to write it; and I should be as proud to be delivered of a Telephone Directory con amore as I should be ashamed to create a Blank Verse Tragedy at the bidding of others."

in The Mating Season) by creating fatuous parodies of the Christopher Robin poems in some of his later stories, and claiming that Milne "was probably jealous of all other writers.... But I loved his stuff." Milne married Dorothy "Daphne" de Sélincourt (1890–1971) in 1913 and their son Christopher Robin Milne was born in 1920. In 1925, Milne bought a country home, Cotchford Farm, in Hartfield, East Sussex. During World War II, Milne was a captain in the British Home Guard in Hartfield & Forest Row, insisting on being plain "Mr. Milne" to the members of his platoon. He retired to the farm after a stroke and brain surgery in 1952 left him an invalid, and by August 1953, "he seemed very old and disenchanted." Milne died in January 1956, aged 74. Literary career 1903 to 1925 After graduating from Cambridge University in 1903, A. A. Milne contributed humorous verse and whimsical essays to Punch, joining the staff in 1906 and becoming an assistant editor. During this period he published 18 plays and three novels, including the murder mystery The Red House Mystery (1922). His son was born in August 1920 and in 1924 Milne produced a collection of children's poems, When We Were Very Young, which were illustrated by Punch staff cartoonist E. H. Shepard. A collection of short stories for children A Gallery of Children, and other stories that became part of the Winnie-the-Pooh books, were first published in 1925. Milne was an early screenwriter for the nascent British film industry, writing four stories filmed in 1920 for the company Minerva Films (founded in 1920 by the actor Leslie Howard and his friend and story editor Adrian Brunel). These were The Bump, starring Aubrey Smith; Twice Two; Five Pound Reward; and Bookworms. Some of these films survive in the archives of the British Film Institute. Milne had met Howard when the actor starred in Milne's play Mr Pim Passes By in London. Looking back on this period (in 1926), Milne observed that when he told his agent that he was going to write a detective story, he was told that what the country wanted from a "Punch humorist" was a humorous story; when two years later he said he was writing nursery rhymes, his agent and publisher were convinced he should write another detective story; and after another two years, he was being told that writing a detective story would be in the worst of taste given the demand for children's books. He concluded that "the only excuse which I have yet discovered for writing anything is that I want to write it; and I should be as proud to be delivered of a Telephone Directory con amore as I should be ashamed to create a Blank Verse Tragedy at the bidding of others."

1926 to 1928 Milne is most famous for his two Pooh books about a boy named Christopher Robin after his son, Christopher Robin Milne (1920–1996), and various characters inspired by his son's stuffed animals, most notably the bear named Winnie-the-Pooh. Christopher Robin Milne's stuffed bear, originally named Edward, was renamed Winnie after a Canadian black bear named Winnie (after Winnipeg), which was used as a military mascot in World War I, and left to London Zoo during the war. "The Pooh" comes from a swan the young Milne named "Pooh". E. H. Shepard illustrated the original Pooh books, using his own son's teddy Growler ("a magnificent bear") as the model. The rest of Christopher Robin Milne's toys, Piglet, Eeyore, Kanga, Roo and Tigger, were incorporated into A. A. Milne's stories, and two more characters – Rabbit and Owl – were created by Milne's imagination. Christopher Robin Milne's own toys are now on display in New York where 750,000 people visit them every year. The fictional Hundred Acre Wood of the Pooh stories derives from Five Hundred Acre Wood in Ashdown Forest in East Sussex, South East England, where the Pooh stories were set. Milne lived on the northern edge of the forest at Cotchford Farm, , and took his son walking there. E. H. Shepard drew on the landscapes of Ashdown Forest as inspiration for many of the illustrations he provided for the Pooh books. The adult Christopher Robin commented: "Pooh's Forest and Ashdown Forest are identical." Popular tourist locations at Ashdown Forest include: Galleon's Lap, The Enchanted Place, the Heffalump Trap and Lone Pine, Eeyore’s Sad and Gloomy Place, and the wooden Pooh Bridge where Pooh and Piglet invented Poohsticks. Not yet known as Pooh, he made his first appearance in a poem, "Teddy Bear", published in Punch magazine in February 1924 and republished in When We Were Very Young. Pooh first appeared in the London Evening News on Christmas Eve, 1925, in a story called "The Wrong Sort of Bees". Winnie-the-Pooh was published in 1926, followed by The House at Pooh Corner in 1928. A second collection of nursery rhymes, Now We Are Six, was published in 1927. All four books were illustrated by E. H. Shepard. Milne also published four plays in this period. He also "gallantly stepped forward" to contribute a quarter of the costs of dramatising P. G. Wodehouse's A Damsel in Distress. The World of Pooh won the Lewis Carroll Shelf Award in 1958.

1926 to 1928 Milne is most famous for his two Pooh books about a boy named Christopher Robin after his son, Christopher Robin Milne (1920–1996), and various characters inspired by his son's stuffed animals, most notably the bear named Winnie-the-Pooh. Christopher Robin Milne's stuffed bear, originally named Edward, was renamed Winnie after a Canadian black bear named Winnie (after Winnipeg), which was used as a military mascot in World War I, and left to London Zoo during the war. "The Pooh" comes from a swan the young Milne named "Pooh". E. H. Shepard illustrated the original Pooh books, using his own son's teddy Growler ("a magnificent bear") as the model. The rest of Christopher Robin Milne's toys, Piglet, Eeyore, Kanga, Roo and Tigger, were incorporated into A. A. Milne's stories, and two more characters – Rabbit and Owl – were created by Milne's imagination. Christopher Robin Milne's own toys are now on display in New York where 750,000 people visit them every year. The fictional Hundred Acre Wood of the Pooh stories derives from Five Hundred Acre Wood in Ashdown Forest in East Sussex, South East England, where the Pooh stories were set. Milne lived on the northern edge of the forest at Cotchford Farm, , and took his son walking there. E. H. Shepard drew on the landscapes of Ashdown Forest as inspiration for many of the illustrations he provided for the Pooh books. The adult Christopher Robin commented: "Pooh's Forest and Ashdown Forest are identical." Popular tourist locations at Ashdown Forest include: Galleon's Lap, The Enchanted Place, the Heffalump Trap and Lone Pine, Eeyore’s Sad and Gloomy Place, and the wooden Pooh Bridge where Pooh and Piglet invented Poohsticks. Not yet known as Pooh, he made his first appearance in a poem, "Teddy Bear", published in Punch magazine in February 1924 and republished in When We Were Very Young. Pooh first appeared in the London Evening News on Christmas Eve, 1925, in a story called "The Wrong Sort of Bees". Winnie-the-Pooh was published in 1926, followed by The House at Pooh Corner in 1928. A second collection of nursery rhymes, Now We Are Six, was published in 1927. All four books were illustrated by E. H. Shepard. Milne also published four plays in this period. He also "gallantly stepped forward" to contribute a quarter of the costs of dramatising P. G. Wodehouse's A Damsel in Distress. The World of Pooh won the Lewis Carroll Shelf Award in 1958.

1926 to 1928 Milne is most famous for his two Pooh books about a boy named Christopher Robin after his son, Christopher Robin Milne (1920–1996), and various characters inspired by his son's stuffed animals, most notably the bear named Winnie-the-Pooh. Christopher Robin Milne's stuffed bear, originally named Edward, was renamed Winnie after a Canadian black bear named Winnie (after Winnipeg), which was used as a military mascot in World War I, and left to London Zoo during the war. "The Pooh" comes from a swan the young Milne named "Pooh". E. H. Shepard illustrated the original Pooh books, using his own son's teddy Growler ("a magnificent bear") as the model. The rest of Christopher Robin Milne's toys, Piglet, Eeyore, Kanga, Roo and Tigger, were incorporated into A. A. Milne's stories, and two more characters – Rabbit and Owl – were created by Milne's imagination. Christopher Robin Milne's own toys are now on display in New York where 750,000 people visit them every year. The fictional Hundred Acre Wood of the Pooh stories derives from Five Hundred Acre Wood in Ashdown Forest in East Sussex, South East England, where the Pooh stories were set. Milne lived on the northern edge of the forest at Cotchford Farm, , and took his son walking there. E. H. Shepard drew on the landscapes of Ashdown Forest as inspiration for many of the illustrations he provided for the Pooh books. The adult Christopher Robin commented: "Pooh's Forest and Ashdown Forest are identical." Popular tourist locations at Ashdown Forest include: Galleon's Lap, The Enchanted Place, the Heffalump Trap and Lone Pine, Eeyore’s Sad and Gloomy Place, and the wooden Pooh Bridge where Pooh and Piglet invented Poohsticks. Not yet known as Pooh, he made his first appearance in a poem, "Teddy Bear", published in Punch magazine in February 1924 and republished in When We Were Very Young. Pooh first appeared in the London Evening News on Christmas Eve, 1925, in a story called "The Wrong Sort of Bees". Winnie-the-Pooh was published in 1926, followed by The House at Pooh Corner in 1928. A second collection of nursery rhymes, Now We Are Six, was published in 1927. All four books were illustrated by E. H. Shepard. Milne also published four plays in this period. He also "gallantly stepped forward" to contribute a quarter of the costs of dramatising P. G. Wodehouse's A Damsel in Distress. The World of Pooh won the Lewis Carroll Shelf Award in 1958.

1929 onwards The success of his children's books was to become a source of considerable annoyance to Milne, whose self-avowed aim was to write whatever he pleased and who had, until then, found a ready audience for each change of direction: he had freed pre-war Punch from its ponderous facetiousness; he had made a considerable reputation as a playwright (like his idol J. M. Barrie) on both sides of the Atlantic; he had produced a witty piece of detective writing in The Red House Mystery (although this was severely criticised by Raymond Chandler for the implausibility of its plot in his essay The Simple Art of Murder in the eponymous collection that appeared in 1950). But once Milne had, in his own words, "said goodbye to all that in 70,000 words" (the approximate length of his four principal children's books), he had no intention of producing any reworkings lacking in originality, given that one of the sources of inspiration, his son, was growing older. Another reason Milne stopped writing children's books, and especially about Winnie-the-Pooh, was that he felt "amazement and disgust" over the fame his son was exposed to, and said that "I feel that the legal Christopher Robin has already had more publicity than I want for him. I do not want CR Milne to ever wish that his name were Charles Robert." In his literary home, Punch, where the When We Were Very Young verses had first appeared, Methuen continued to publish whatever Milne wrote, including the long poem "The Norman Church" and an assembly of articles entitled Year In, Year Out (which Milne likened to a benefit night for the author). In 1930, Milne adapted Kenneth Grahame's novel The Wind in the Willows for the stage as Toad of Toad Hall. The title was an implicit admission that such chapters as Chapter 7, "The Piper at the Gates of Dawn," could not survive translation to the theatre. A special introduction written by Milne is included in some editions of Grahame's novel. Milne and his wife became estranged from their son, who came to resent what he saw as his father's exploitation of his childhood and came to hate the books that had thrust him into the public eye. Christopher's marriage to his first cousin, Lesley de Sélincourt, distanced him still further from his parents – Lesley's father and Christopher's mother had not spoken to each other for 30 years. Death and legacy Commemoration A. A. Milne died at his home in Hartfield, Sussex, on 31 January 1956, nearly two weeks after his 74th birthday. After a memorial service in London, his ashes were scattered in a crematorium's memorial garden in Brighton. The rights to A. A. Milne's Pooh books were left to four beneficiaries: his family, the Royal Literary Fund, Westminster School and the Garrick Club.

1929 onwards The success of his children's books was to become a source of considerable annoyance to Milne, whose self-avowed aim was to write whatever he pleased and who had, until then, found a ready audience for each change of direction: he had freed pre-war Punch from its ponderous facetiousness; he had made a considerable reputation as a playwright (like his idol J. M. Barrie) on both sides of the Atlantic; he had produced a witty piece of detective writing in The Red House Mystery (although this was severely criticised by Raymond Chandler for the implausibility of its plot in his essay The Simple Art of Murder in the eponymous collection that appeared in 1950). But once Milne had, in his own words, "said goodbye to all that in 70,000 words" (the approximate length of his four principal children's books), he had no intention of producing any reworkings lacking in originality, given that one of the sources of inspiration, his son, was growing older. Another reason Milne stopped writing children's books, and especially about Winnie-the-Pooh, was that he felt "amazement and disgust" over the fame his son was exposed to, and said that "I feel that the legal Christopher Robin has already had more publicity than I want for him. I do not want CR Milne to ever wish that his name were Charles Robert." In his literary home, Punch, where the When We Were Very Young verses had first appeared, Methuen continued to publish whatever Milne wrote, including the long poem "The Norman Church" and an assembly of articles entitled Year In, Year Out (which Milne likened to a benefit night for the author). In 1930, Milne adapted Kenneth Grahame's novel The Wind in the Willows for the stage as Toad of Toad Hall. The title was an implicit admission that such chapters as Chapter 7, "The Piper at the Gates of Dawn," could not survive translation to the theatre. A special introduction written by Milne is included in some editions of Grahame's novel. Milne and his wife became estranged from their son, who came to resent what he saw as his father's exploitation of his childhood and came to hate the books that had thrust him into the public eye. Christopher's marriage to his first cousin, Lesley de Sélincourt, distanced him still further from his parents – Lesley's father and Christopher's mother had not spoken to each other for 30 years. Death and legacy Commemoration A. A. Milne died at his home in Hartfield, Sussex, on 31 January 1956, nearly two weeks after his 74th birthday. After a memorial service in London, his ashes were scattered in a crematorium's memorial garden in Brighton. The rights to A. A. Milne's Pooh books were left to four beneficiaries: his family, the Royal Literary Fund, Westminster School and the Garrick Club.

1929 onwards The success of his children's books was to become a source of considerable annoyance to Milne, whose self-avowed aim was to write whatever he pleased and who had, until then, found a ready audience for each change of direction: he had freed pre-war Punch from its ponderous facetiousness; he had made a considerable reputation as a playwright (like his idol J. M. Barrie) on both sides of the Atlantic; he had produced a witty piece of detective writing in The Red House Mystery (although this was severely criticised by Raymond Chandler for the implausibility of its plot in his essay The Simple Art of Murder in the eponymous collection that appeared in 1950). But once Milne had, in his own words, "said goodbye to all that in 70,000 words" (the approximate length of his four principal children's books), he had no intention of producing any reworkings lacking in originality, given that one of the sources of inspiration, his son, was growing older. Another reason Milne stopped writing children's books, and especially about Winnie-the-Pooh, was that he felt "amazement and disgust" over the fame his son was exposed to, and said that "I feel that the legal Christopher Robin has already had more publicity than I want for him. I do not want CR Milne to ever wish that his name were Charles Robert." In his literary home, Punch, where the When We Were Very Young verses had first appeared, Methuen continued to publish whatever Milne wrote, including the long poem "The Norman Church" and an assembly of articles entitled Year In, Year Out (which Milne likened to a benefit night for the author). In 1930, Milne adapted Kenneth Grahame's novel The Wind in the Willows for the stage as Toad of Toad Hall. The title was an implicit admission that such chapters as Chapter 7, "The Piper at the Gates of Dawn," could not survive translation to the theatre. A special introduction written by Milne is included in some editions of Grahame's novel. Milne and his wife became estranged from their son, who came to resent what he saw as his father's exploitation of his childhood and came to hate the books that had thrust him into the public eye. Christopher's marriage to his first cousin, Lesley de Sélincourt, distanced him still further from his parents – Lesley's father and Christopher's mother had not spoken to each other for 30 years. Death and legacy Commemoration A. A. Milne died at his home in Hartfield, Sussex, on 31 January 1956, nearly two weeks after his 74th birthday. After a memorial service in London, his ashes were scattered in a crematorium's memorial garden in Brighton. The rights to A. A. Milne's Pooh books were left to four beneficiaries: his family, the Royal Literary Fund, Westminster School and the Garrick Club.

After Milne's death in 1956, thirteen days after his 74th birthday, his widow sold her rights to the Pooh characters to Stephen Slesinger, whose widow sold the rights after Slesinger's death to the Walt Disney Company, which has made many Pooh cartoon movies, a Disney Channel television show, as well as Pooh-related merchandise. In 2001, the other beneficiaries sold their interest in the estate to the Disney Corporation for $350m. Previously Disney had been paying twice-yearly royalties to these beneficiaries. The estate of E. H. Shepard also received a sum in the deal. The UK copyright on the text of the original Winnie the Pooh books expires on 1 January 2027; at the beginning of the year after the 70th anniversary of the author's death (PMA-70), and has already expired in those countries with a PMA-50 rule. This applies to all of Milne's works except those first published posthumously. The illustrations in the Pooh books will remain under copyright until the same amount of time has passed, after the illustrator's death; in the UK, this will be on 1 January 2047. In the United States, copyright will not expire until 95 years after publication for each of Milne's books first published before 1978, but this includes the illustrations. In 2008, a collection of original illustrations featuring Winnie-the-Pooh and his animal friends sold for more than £1.2 million at auction in Sotheby's, London. Forbes magazine ranked Winnie the Pooh the most valuable fictional character in 2002; Winnie the Pooh merchandising products alone had annual sales of more than $5.9 billion. In 2005, Winnie the Pooh generated $6 billion, a figure surpassed only by Mickey Mouse. A memorial plaque in Ashdown Forest, unveiled by Christopher Robin in 1979, commemorates the work of A. A. Milne and Shepard in creating the world of Pooh. Milne once wrote of Ashdown Forest: "In that enchanted place on the top of the forest a little boy and his bear will always be playing." In 2003, Winnie the Pooh was listed at number 7 on the BBC's poll The Big Read which determined the UK's "best-loved novels" of all time. In 2006, Winnie the Pooh received a star on the Hollywood Walk of Fame, marking the 80th birthday of Milne's creation. That same year a UK poll saw Winnie the Pooh voted onto the list of icons of England. Marking the 90th anniversary of Milne's creation of the character, and the 90th birthday of Elizabeth II, in 2016 a new story sees Winnie the Pooh meet the Queen at Buckingham Palace. The illustrated and audio adventure is titled Winnie-the-Pooh Meets the Queen, and has been narrated by actor Jim Broadbent. Also in 2016, a new character, a Penguin, was unveiled in The Best Bear in All the World, which was inspired by a long-lost photograph of Milne and his son Christopher with a toy penguin. Several of Milne's children's poems were set to music by the composer Harold Fraser-Simson.

After Milne's death in 1956, thirteen days after his 74th birthday, his widow sold her rights to the Pooh characters to Stephen Slesinger, whose widow sold the rights after Slesinger's death to the Walt Disney Company, which has made many Pooh cartoon movies, a Disney Channel television show, as well as Pooh-related merchandise. In 2001, the other beneficiaries sold their interest in the estate to the Disney Corporation for $350m. Previously Disney had been paying twice-yearly royalties to these beneficiaries. The estate of E. H. Shepard also received a sum in the deal. The UK copyright on the text of the original Winnie the Pooh books expires on 1 January 2027; at the beginning of the year after the 70th anniversary of the author's death (PMA-70), and has already expired in those countries with a PMA-50 rule. This applies to all of Milne's works except those first published posthumously. The illustrations in the Pooh books will remain under copyright until the same amount of time has passed, after the illustrator's death; in the UK, this will be on 1 January 2047. In the United States, copyright will not expire until 95 years after publication for each of Milne's books first published before 1978, but this includes the illustrations. In 2008, a collection of original illustrations featuring Winnie-the-Pooh and his animal friends sold for more than £1.2 million at auction in Sotheby's, London. Forbes magazine ranked Winnie the Pooh the most valuable fictional character in 2002; Winnie the Pooh merchandising products alone had annual sales of more than $5.9 billion. In 2005, Winnie the Pooh generated $6 billion, a figure surpassed only by Mickey Mouse. A memorial plaque in Ashdown Forest, unveiled by Christopher Robin in 1979, commemorates the work of A. A. Milne and Shepard in creating the world of Pooh. Milne once wrote of Ashdown Forest: "In that enchanted place on the top of the forest a little boy and his bear will always be playing." In 2003, Winnie the Pooh was listed at number 7 on the BBC's poll The Big Read which determined the UK's "best-loved novels" of all time. In 2006, Winnie the Pooh received a star on the Hollywood Walk of Fame, marking the 80th birthday of Milne's creation. That same year a UK poll saw Winnie the Pooh voted onto the list of icons of England. Marking the 90th anniversary of Milne's creation of the character, and the 90th birthday of Elizabeth II, in 2016 a new story sees Winnie the Pooh meet the Queen at Buckingham Palace. The illustrated and audio adventure is titled Winnie-the-Pooh Meets the Queen, and has been narrated by actor Jim Broadbent. Also in 2016, a new character, a Penguin, was unveiled in The Best Bear in All the World, which was inspired by a long-lost photograph of Milne and his son Christopher with a toy penguin. Several of Milne's children's poems were set to music by the composer Harold Fraser-Simson.

After Milne's death in 1956, thirteen days after his 74th birthday, his widow sold her rights to the Pooh characters to Stephen Slesinger, whose widow sold the rights after Slesinger's death to the Walt Disney Company, which has made many Pooh cartoon movies, a Disney Channel television show, as well as Pooh-related merchandise. In 2001, the other beneficiaries sold their interest in the estate to the Disney Corporation for $350m. Previously Disney had been paying twice-yearly royalties to these beneficiaries. The estate of E. H. Shepard also received a sum in the deal. The UK copyright on the text of the original Winnie the Pooh books expires on 1 January 2027; at the beginning of the year after the 70th anniversary of the author's death (PMA-70), and has already expired in those countries with a PMA-50 rule. This applies to all of Milne's works except those first published posthumously. The illustrations in the Pooh books will remain under copyright until the same amount of time has passed, after the illustrator's death; in the UK, this will be on 1 January 2047. In the United States, copyright will not expire until 95 years after publication for each of Milne's books first published before 1978, but this includes the illustrations. In 2008, a collection of original illustrations featuring Winnie-the-Pooh and his animal friends sold for more than £1.2 million at auction in Sotheby's, London. Forbes magazine ranked Winnie the Pooh the most valuable fictional character in 2002; Winnie the Pooh merchandising products alone had annual sales of more than $5.9 billion. In 2005, Winnie the Pooh generated $6 billion, a figure surpassed only by Mickey Mouse. A memorial plaque in Ashdown Forest, unveiled by Christopher Robin in 1979, commemorates the work of A. A. Milne and Shepard in creating the world of Pooh. Milne once wrote of Ashdown Forest: "In that enchanted place on the top of the forest a little boy and his bear will always be playing." In 2003, Winnie the Pooh was listed at number 7 on the BBC's poll The Big Read which determined the UK's "best-loved novels" of all time. In 2006, Winnie the Pooh received a star on the Hollywood Walk of Fame, marking the 80th birthday of Milne's creation. That same year a UK poll saw Winnie the Pooh voted onto the list of icons of England. Marking the 90th anniversary of Milne's creation of the character, and the 90th birthday of Elizabeth II, in 2016 a new story sees Winnie the Pooh meet the Queen at Buckingham Palace. The illustrated and audio adventure is titled Winnie-the-Pooh Meets the Queen, and has been narrated by actor Jim Broadbent. Also in 2016, a new character, a Penguin, was unveiled in The Best Bear in All the World, which was inspired by a long-lost photograph of Milne and his son Christopher with a toy penguin. Several of Milne's children's poems were set to music by the composer Harold Fraser-Simson.

His poems have been parodied many times, including with the books When We Were Rather Older and Now We Are Sixty. The 1963 film The King's Breakfast was based on Milne's poem of the same name. The Pooh books were used as the basis for two academic satires by Frederick C Crews: 'The Pooh Perplex'(1963–4) and 'Postmodern Pooh'(2002). An exhibition entitled "Winnie-the-Pooh: Exploring a Classic" appeared at the V & A from 9 December 2017 to 8 April 2018. An elementary school in Houston, Texas, United States, operated by the Houston Independent School District (HISD), is named after Milne. The school, A. A. Milne Elementary School in Brays Oaks, opened in 1991. Archive The bulk of A. A. Milne's papers are housed at the Harry Ransom Center at the University of Texas at Austin. The collection, established at the center in 1964, consists of manuscript drafts and fragments for over 150 of Milne's works, as well as correspondence, legal documents, genealogical records, and some personal effects. The library division holds several books formerly belonging to Milne and his wife Dorothy. The Harry Ransom Center also has small collections of correspondence from Christopher Robin Milne and Milne's frequent illustrator Ernest Shepard. The original manuscripts for Winnie the Pooh and The House at Pooh Corner are archived separately at Trinity College Library, Cambridge. Religious views Milne did not speak out much on the subject of religion, although he used religious terms to explain his decision, while remaining a pacifist, to join the British Home Guard: "In fighting Hitler," he wrote, "we are truly fighting the Devil, the Anti-Christ ... Hitler was a crusader against God." His best known comment on the subject was recalled on his death: He wrote in the poem "Explained": He also wrote in the poem "Vespers": Works Novels Lovers in London (1905. Some consider this more of a short story collection; Milne did not like it and considered The Day's Play as his first book.) Once on a Time (1917) Mr. Pim (1921) (A novelisation of his 1919 play Mr. Pim Passes By) The Red House Mystery (1922). Serialised: London (Daily News), serialised daily from 3 to 28 August 1921 Two People (1931) (Inside jacket claims this is Milne's first attempt at a novel.) Four Days' Wonder (1933) Chloe Marr (1946) Non-fiction Peace With Honour (1934) It's Too Late Now: The Autobiography of a Writer (1939) War With Honour (1940) War Aims Unlimited (1941) Year In, Year Out (1952) (illustrated by E. H. Shepard) Punch articles The Day's Play (1910) The Holiday Round (1912) Once a Week (1914) The Sunny Side (1921) Those Were the Days (1929) [The four volumes above, compiled] Newspaper articles and book introductions The Chronicles of Clovis by "Saki" (1911) [Introduction to] Not That It Matters (1919) If I May (1920) By Way of Introduction (1929) ‘'Women and Children First!’’.

His poems have been parodied many times, including with the books When We Were Rather Older and Now We Are Sixty. The 1963 film The King's Breakfast was based on Milne's poem of the same name. The Pooh books were used as the basis for two academic satires by Frederick C Crews: 'The Pooh Perplex'(1963–4) and 'Postmodern Pooh'(2002). An exhibition entitled "Winnie-the-Pooh: Exploring a Classic" appeared at the V & A from 9 December 2017 to 8 April 2018. An elementary school in Houston, Texas, United States, operated by the Houston Independent School District (HISD), is named after Milne. The school, A. A. Milne Elementary School in Brays Oaks, opened in 1991. Archive The bulk of A. A. Milne's papers are housed at the Harry Ransom Center at the University of Texas at Austin. The collection, established at the center in 1964, consists of manuscript drafts and fragments for over 150 of Milne's works, as well as correspondence, legal documents, genealogical records, and some personal effects. The library division holds several books formerly belonging to Milne and his wife Dorothy. The Harry Ransom Center also has small collections of correspondence from Christopher Robin Milne and Milne's frequent illustrator Ernest Shepard. The original manuscripts for Winnie the Pooh and The House at Pooh Corner are archived separately at Trinity College Library, Cambridge. Religious views Milne did not speak out much on the subject of religion, although he used religious terms to explain his decision, while remaining a pacifist, to join the British Home Guard: "In fighting Hitler," he wrote, "we are truly fighting the Devil, the Anti-Christ ... Hitler was a crusader against God." His best known comment on the subject was recalled on his death: He wrote in the poem "Explained": He also wrote in the poem "Vespers": Works Novels Lovers in London (1905. Some consider this more of a short story collection; Milne did not like it and considered The Day's Play as his first book.) Once on a Time (1917) Mr. Pim (1921) (A novelisation of his 1919 play Mr. Pim Passes By) The Red House Mystery (1922). Serialised: London (Daily News), serialised daily from 3 to 28 August 1921 Two People (1931) (Inside jacket claims this is Milne's first attempt at a novel.) Four Days' Wonder (1933) Chloe Marr (1946) Non-fiction Peace With Honour (1934) It's Too Late Now: The Autobiography of a Writer (1939) War With Honour (1940) War Aims Unlimited (1941) Year In, Year Out (1952) (illustrated by E. H. Shepard) Punch articles The Day's Play (1910) The Holiday Round (1912) Once a Week (1914) The Sunny Side (1921) Those Were the Days (1929) [The four volumes above, compiled] Newspaper articles and book introductions The Chronicles of Clovis by "Saki" (1911) [Introduction to] Not That It Matters (1919) If I May (1920) By Way of Introduction (1929) ‘'Women and Children First!’’.

His poems have been parodied many times, including with the books When We Were Rather Older and Now We Are Sixty. The 1963 film The King's Breakfast was based on Milne's poem of the same name. The Pooh books were used as the basis for two academic satires by Frederick C Crews: 'The Pooh Perplex'(1963–4) and 'Postmodern Pooh'(2002). An exhibition entitled "Winnie-the-Pooh: Exploring a Classic" appeared at the V & A from 9 December 2017 to 8 April 2018. An elementary school in Houston, Texas, United States, operated by the Houston Independent School District (HISD), is named after Milne. The school, A. A. Milne Elementary School in Brays Oaks, opened in 1991. Archive The bulk of A. A. Milne's papers are housed at the Harry Ransom Center at the University of Texas at Austin. The collection, established at the center in 1964, consists of manuscript drafts and fragments for over 150 of Milne's works, as well as correspondence, legal documents, genealogical records, and some personal effects. The library division holds several books formerly belonging to Milne and his wife Dorothy. The Harry Ransom Center also has small collections of correspondence from Christopher Robin Milne and Milne's frequent illustrator Ernest Shepard. The original manuscripts for Winnie the Pooh and The House at Pooh Corner are archived separately at Trinity College Library, Cambridge. Religious views Milne did not speak out much on the subject of religion, although he used religious terms to explain his decision, while remaining a pacifist, to join the British Home Guard: "In fighting Hitler," he wrote, "we are truly fighting the Devil, the Anti-Christ ... Hitler was a crusader against God." His best known comment on the subject was recalled on his death: He wrote in the poem "Explained": He also wrote in the poem "Vespers": Works Novels Lovers in London (1905. Some consider this more of a short story collection; Milne did not like it and considered The Day's Play as his first book.) Once on a Time (1917) Mr. Pim (1921) (A novelisation of his 1919 play Mr. Pim Passes By) The Red House Mystery (1922). Serialised: London (Daily News), serialised daily from 3 to 28 August 1921 Two People (1931) (Inside jacket claims this is Milne's first attempt at a novel.) Four Days' Wonder (1933) Chloe Marr (1946) Non-fiction Peace With Honour (1934) It's Too Late Now: The Autobiography of a Writer (1939) War With Honour (1940) War Aims Unlimited (1941) Year In, Year Out (1952) (illustrated by E. H. Shepard) Punch articles The Day's Play (1910) The Holiday Round (1912) Once a Week (1914) The Sunny Side (1921) Those Were the Days (1929) [The four volumes above, compiled] Newspaper articles and book introductions The Chronicles of Clovis by "Saki" (1911) [Introduction to] Not That It Matters (1919) If I May (1920) By Way of Introduction (1929) ‘'Women and Children First!’’.

John Bull, 10 November 1934 It Depends on the Book (1943, in September issue of Red Cross Newspaper The Prisoner of War) Story collections for children A Gallery of Children (1925) Winnie-the-Pooh (1926) (illustrated by Ernest H. Shepard) The House at Pooh Corner (1928) (illustrated by E. H. Shepard) Short Stories Poetry collections for children When We Were Very Young (1924) (illustrated by E. H. Shepard) Now We Are Six (1927) (illustrated by E. H. Shepard) Story collections The Secret and other stories (1929) The Birthday Party (1948) A Table Near the Band (1950) Poetry When We Were Very Young (1924) (illustrated by E. H. Shepard) For the Luncheon Interval (1925) [poems from Punch] Now We Are Six (1927) (illustrated by E. H. Shepard) Behind the Lines (1940) The Norman Church (1948) Screenplays and plays Wurzel-Flummery (1917) Belinda (1918) The Boy Comes Home (1918) Make-Believe (1918) (children's play) The Camberley Triangle (1919) Mr. Pim Passes By (1919) The Red Feathers (1920) The Romantic Age (1920) The Stepmother (1920) The Truth About Blayds (1920) The Bump (1920, Minerva Films), starring C. Aubrey Smith and Faith Celli Twice Two (1920, Minerva Films) Five Pound Reward (1920, Minerva Films) Bookworms (1920, Minerva Films) The Great Broxopp (1921) The Dover Road (1921) The Lucky One (1922) The Truth About Blayds (1922) The Artist: A Duologue (1923) Give Me Yesterday (1923) (a.k.a. Success in the UK) Ariadne (1924) The Man in the Bowler Hat: A Terribly Exciting Affair (1924) To Have the Honour (1924) Portrait of a Gentleman in Slippers (1926) Success (1926) Miss Marlow at Play (1927) Winnie the Pooh. Written specially by Milne for a 'Winnie the Pooh Party' in aid of the National Mother-Saving Campaign, and performed once at Seaford House on 17 March 1928 The Fourth Wall or The Perfect Alibi (1928) (later adapted for the film Birds of Prey (1930), directed by Basil Dean) The Ivory Door (1929) Toad of Toad Hall (1929) (adaptation of The Wind in the Willows) Michael and Mary (1930) Other People's Lives (1933) (a.k.a. They Don't Mean Any Harm) Miss Elizabeth Bennet (1936) [based on Pride and Prejudice] Sarah Simple (1937) Gentleman Unknown (1938) The General Takes Off His Helmet (1939) in The Queen's Book of the Red Cross The Ugly Duckling (1941) Before the Flood (1951). Portrayal Milne is portrayed by Domhnall Gleeson in Goodbye Christopher Robin, a 2017 film. In the 2018 fantasy film Christopher Robin, an extension of the Disney Winnie the Pooh franchise, Tristan Sturrock plays A.A. Milne. References Further reading Thwaite, Ann. A.A. Milne: His Life. London: Faber and Faber, 1990. Toby, Marlene. A.A. Milne, Author of Winnie-the-Pooh. Chicago: Children's Press, 1995. External links A. A. Milne Papers at the Harry Ransom Center Works by A. A. Milne at BiblioWiki (Canada) includes the complete text of the four Pooh books Portraits of A. A. Milne in the National Portrait Gallery Essays by Milne at Quotidiana.org Milne extract in The Guardian Profile at Just-Pooh.com A.

John Bull, 10 November 1934 It Depends on the Book (1943, in September issue of Red Cross Newspaper The Prisoner of War) Story collections for children A Gallery of Children (1925) Winnie-the-Pooh (1926) (illustrated by Ernest H. Shepard) The House at Pooh Corner (1928) (illustrated by E. H. Shepard) Short Stories Poetry collections for children When We Were Very Young (1924) (illustrated by E. H. Shepard) Now We Are Six (1927) (illustrated by E. H. Shepard) Story collections The Secret and other stories (1929) The Birthday Party (1948) A Table Near the Band (1950) Poetry When We Were Very Young (1924) (illustrated by E. H. Shepard) For the Luncheon Interval (1925) [poems from Punch] Now We Are Six (1927) (illustrated by E. H. Shepard) Behind the Lines (1940) The Norman Church (1948) Screenplays and plays Wurzel-Flummery (1917) Belinda (1918) The Boy Comes Home (1918) Make-Believe (1918) (children's play) The Camberley Triangle (1919) Mr. Pim Passes By (1919) The Red Feathers (1920) The Romantic Age (1920) The Stepmother (1920) The Truth About Blayds (1920) The Bump (1920, Minerva Films), starring C. Aubrey Smith and Faith Celli Twice Two (1920, Minerva Films) Five Pound Reward (1920, Minerva Films) Bookworms (1920, Minerva Films) The Great Broxopp (1921) The Dover Road (1921) The Lucky One (1922) The Truth About Blayds (1922) The Artist: A Duologue (1923) Give Me Yesterday (1923) (a.k.a. Success in the UK) Ariadne (1924) The Man in the Bowler Hat: A Terribly Exciting Affair (1924) To Have the Honour (1924) Portrait of a Gentleman in Slippers (1926) Success (1926) Miss Marlow at Play (1927) Winnie the Pooh. Written specially by Milne for a 'Winnie the Pooh Party' in aid of the National Mother-Saving Campaign, and performed once at Seaford House on 17 March 1928 The Fourth Wall or The Perfect Alibi (1928) (later adapted for the film Birds of Prey (1930), directed by Basil Dean) The Ivory Door (1929) Toad of Toad Hall (1929) (adaptation of The Wind in the Willows) Michael and Mary (1930) Other People's Lives (1933) (a.k.a. They Don't Mean Any Harm) Miss Elizabeth Bennet (1936) [based on Pride and Prejudice] Sarah Simple (1937) Gentleman Unknown (1938) The General Takes Off His Helmet (1939) in The Queen's Book of the Red Cross The Ugly Duckling (1941) Before the Flood (1951). Portrayal Milne is portrayed by Domhnall Gleeson in Goodbye Christopher Robin, a 2017 film. In the 2018 fantasy film Christopher Robin, an extension of the Disney Winnie the Pooh franchise, Tristan Sturrock plays A.A. Milne. References Further reading Thwaite, Ann. A.A. Milne: His Life. London: Faber and Faber, 1990. Toby, Marlene. A.A. Milne, Author of Winnie-the-Pooh. Chicago: Children's Press, 1995. External links A. A. Milne Papers at the Harry Ransom Center Works by A. A. Milne at BiblioWiki (Canada) includes the complete text of the four Pooh books Portraits of A. A. Milne in the National Portrait Gallery Essays by Milne at Quotidiana.org Milne extract in The Guardian Profile at Just-Pooh.com A.

John Bull, 10 November 1934 It Depends on the Book (1943, in September issue of Red Cross Newspaper The Prisoner of War) Story collections for children A Gallery of Children (1925) Winnie-the-Pooh (1926) (illustrated by Ernest H. Shepard) The House at Pooh Corner (1928) (illustrated by E. H. Shepard) Short Stories Poetry collections for children When We Were Very Young (1924) (illustrated by E. H. Shepard) Now We Are Six (1927) (illustrated by E. H. Shepard) Story collections The Secret and other stories (1929) The Birthday Party (1948) A Table Near the Band (1950) Poetry When We Were Very Young (1924) (illustrated by E. H. Shepard) For the Luncheon Interval (1925) [poems from Punch] Now We Are Six (1927) (illustrated by E. H. Shepard) Behind the Lines (1940) The Norman Church (1948) Screenplays and plays Wurzel-Flummery (1917) Belinda (1918) The Boy Comes Home (1918) Make-Believe (1918) (children's play) The Camberley Triangle (1919) Mr. Pim Passes By (1919) The Red Feathers (1920) The Romantic Age (1920) The Stepmother (1920) The Truth About Blayds (1920) The Bump (1920, Minerva Films), starring C. Aubrey Smith and Faith Celli Twice Two (1920, Minerva Films) Five Pound Reward (1920, Minerva Films) Bookworms (1920, Minerva Films) The Great Broxopp (1921) The Dover Road (1921) The Lucky One (1922) The Truth About Blayds (1922) The Artist: A Duologue (1923) Give Me Yesterday (1923) (a.k.a. Success in the UK) Ariadne (1924) The Man in the Bowler Hat: A Terribly Exciting Affair (1924) To Have the Honour (1924) Portrait of a Gentleman in Slippers (1926) Success (1926) Miss Marlow at Play (1927) Winnie the Pooh. Written specially by Milne for a 'Winnie the Pooh Party' in aid of the National Mother-Saving Campaign, and performed once at Seaford House on 17 March 1928 The Fourth Wall or The Perfect Alibi (1928) (later adapted for the film Birds of Prey (1930), directed by Basil Dean) The Ivory Door (1929) Toad of Toad Hall (1929) (adaptation of The Wind in the Willows) Michael and Mary (1930) Other People's Lives (1933) (a.k.a. They Don't Mean Any Harm) Miss Elizabeth Bennet (1936) [based on Pride and Prejudice] Sarah Simple (1937) Gentleman Unknown (1938) The General Takes Off His Helmet (1939) in The Queen's Book of the Red Cross The Ugly Duckling (1941) Before the Flood (1951). Portrayal Milne is portrayed by Domhnall Gleeson in Goodbye Christopher Robin, a 2017 film. In the 2018 fantasy film Christopher Robin, an extension of the Disney Winnie the Pooh franchise, Tristan Sturrock plays A.A. Milne. References Further reading Thwaite, Ann. A.A. Milne: His Life. London: Faber and Faber, 1990. Toby, Marlene. A.A. Milne, Author of Winnie-the-Pooh. Chicago: Children's Press, 1995. External links A. A. Milne Papers at the Harry Ransom Center Works by A. A. Milne at BiblioWiki (Canada) includes the complete text of the four Pooh books Portraits of A. A. Milne in the National Portrait Gallery Essays by Milne at Quotidiana.org Milne extract in The Guardian Profile at Just-Pooh.com A.

A. Milne at poeticous.com AA Milne | Books | The Guardian Finding aid to the A.A. Milne letters at Columbia University Rare Book & Manuscript Library 1882 births 1956 deaths English people of Scottish descent People from Hampstead People from Kilburn, London 20th-century British dramatists and playwrights 20th-century British short story writers 20th-century English novelists 20th-century English poets Alumni of Trinity College, Cambridge British Army personnel of World War I British Home Guard officers Royal Warwickshire Fusiliers officers English children's writers Members of the Detection Club People educated at Westminster School, London Punch (magazine) people English male poets Winnie-the-Pooh Writers from London English male novelists Children's poets Royal Corps of Signals officers Military personnel from London

A. Milne at poeticous.com AA Milne | Books | The Guardian Finding aid to the A.A. Milne letters at Columbia University Rare Book & Manuscript Library 1882 births 1956 deaths English people of Scottish descent People from Hampstead People from Kilburn, London 20th-century British dramatists and playwrights 20th-century British short story writers 20th-century English novelists 20th-century English poets Alumni of Trinity College, Cambridge British Army personnel of World War I British Home Guard officers Royal Warwickshire Fusiliers officers English children's writers Members of the Detection Club People educated at Westminster School, London Punch (magazine) people English male poets Winnie-the-Pooh Writers from London English male novelists Children's poets Royal Corps of Signals officers Military personnel from London

A. Milne at poeticous.com AA Milne | Books | The Guardian Finding aid to the A.A. Milne letters at Columbia University Rare Book & Manuscript Library 1882 births 1956 deaths English people of Scottish descent People from Hampstead People from Kilburn, London 20th-century British dramatists and playwrights 20th-century British short story writers 20th-century English novelists 20th-century English poets Alumni of Trinity College, Cambridge British Army personnel of World War I British Home Guard officers Royal Warwickshire Fusiliers officers English children's writers Members of the Detection Club People educated at Westminster School, London Punch (magazine) people English male poets Winnie-the-Pooh Writers from London English male novelists Children's poets Royal Corps of Signals officers Military personnel from London

Asociación Alumni Asociación Alumni, usually just Alumni, is an Argentine rugby union club located in Tortuguitas, Greater Buenos Aires. The senior squad currently competes at Top 12, the first division of the Unión de Rugby de Buenos Aires league system. The club has ties with former football club Alumni because both were established by Buenos Aires English High School students. History Background The first club with the name "Alumni" played association football, having been found in 1898 by students of Buenos Aires English High School (BAEHS) along with director Alexander Watson Hutton. Originally under the name "English High School A.C.", the team would be later obliged by the Association to change its name, therefore "Alumni" was chosen, following a proposal by Carlos Bowers, a former student of the school. Alumni was the most successful team during the first years of Argentine football, winning 10 of 14 league championships contested. Alumni is still considered the first great football team in the country. Alumni was reorganised in 1908, "in order to encourage people to practise all kind of sports, specially football". This was the last try to develop itself as a sports club rather than just a football team, such as Lomas, Belgrano and Quilmes had successfully done in the past, but the efforts were not enough. Alumni played its last game in 1911 and was definitely dissolved on April 24, 1913. Rebirth through rugby In 1951, two guards of the BAEHS, Daniel Ginhson (also a former player of Buenos Aires F.C.) and Guillermo Cubelli, supported by the school's alumni and fathers of the students, they decided to establish a club focused on rugby union exclusively. Former players still alive of Alumni football club and descendants of other players already dead gave their permission to use the name "Alumni". On December 13, in a meeting presided by Carlos Bowers himself (who had proposed the name "Alumni" to the original football team 50 years before), the club was officially established under the name "Asociación Juvenil Alumni", also adopting the same colors as its predecessor. The team achieved good results and in 1960 the club presented a team that won the third division of the Buenos Aires league, reaching the second division. Since then, Alumni has played at the highest level of Argentine rugby and its rivalry with Belgrano Athletic Club is one of the fiercest local derbies in Buenos Aires. Alumni would later climb up to first division winning 5 titles: 4 consecutive between 1989 and 1992, and the other in 2001. In 2002, Alumni won its first Nacional de Clubes title, defeating Jockey Club de Rosario 23–21 in the final.

Asociación Alumni Asociación Alumni, usually just Alumni, is an Argentine rugby union club located in Tortuguitas, Greater Buenos Aires. The senior squad currently competes at Top 12, the first division of the Unión de Rugby de Buenos Aires league system. The club has ties with former football club Alumni because both were established by Buenos Aires English High School students. History Background The first club with the name "Alumni" played association football, having been found in 1898 by students of Buenos Aires English High School (BAEHS) along with director Alexander Watson Hutton. Originally under the name "English High School A.C.", the team would be later obliged by the Association to change its name, therefore "Alumni" was chosen, following a proposal by Carlos Bowers, a former student of the school. Alumni was the most successful team during the first years of Argentine football, winning 10 of 14 league championships contested. Alumni is still considered the first great football team in the country. Alumni was reorganised in 1908, "in order to encourage people to practise all kind of sports, specially football". This was the last try to develop itself as a sports club rather than just a football team, such as Lomas, Belgrano and Quilmes had successfully done in the past, but the efforts were not enough. Alumni played its last game in 1911 and was definitely dissolved on April 24, 1913. Rebirth through rugby In 1951, two guards of the BAEHS, Daniel Ginhson (also a former player of Buenos Aires F.C.) and Guillermo Cubelli, supported by the school's alumni and fathers of the students, they decided to establish a club focused on rugby union exclusively. Former players still alive of Alumni football club and descendants of other players already dead gave their permission to use the name "Alumni". On December 13, in a meeting presided by Carlos Bowers himself (who had proposed the name "Alumni" to the original football team 50 years before), the club was officially established under the name "Asociación Juvenil Alumni", also adopting the same colors as its predecessor. The team achieved good results and in 1960 the club presented a team that won the third division of the Buenos Aires league, reaching the second division. Since then, Alumni has played at the highest level of Argentine rugby and its rivalry with Belgrano Athletic Club is one of the fiercest local derbies in Buenos Aires. Alumni would later climb up to first division winning 5 titles: 4 consecutive between 1989 and 1992, and the other in 2001. In 2002, Alumni won its first Nacional de Clubes title, defeating Jockey Club de Rosario 23–21 in the final.

Players Current roster As of January 2018: Federico Lucca Gaspar Baldunciel Guido Cambareri Iñaki Etchegaray Bernardo Quaranta Tobias Moyano Mariano Romanini Santiago Montagner Tomas Passerotti Lucas Frana Luca Sabato Franco Batezzatti Franco Sabato Rafael Desanto Nito Provenzano Tomas Bivort Juan.P Ceraso Santiago Alduncin Juan.P Anderson Lucas Magnasco Joaquin Diaz Luzzi Felipe Martignone Tomas Corneille Honours Nacional de Clubes (1): 2002 Torneo de la URBA (6): 1989, 1990, 1991, 1992, 2001, 2018 See also Buenos Aires English High School Alumni Athletic Club References External links Rugby clubs established in 1951 A 1951 establishments in Argentina

Players Current roster As of January 2018: Federico Lucca Gaspar Baldunciel Guido Cambareri Iñaki Etchegaray Bernardo Quaranta Tobias Moyano Mariano Romanini Santiago Montagner Tomas Passerotti Lucas Frana Luca Sabato Franco Batezzatti Franco Sabato Rafael Desanto Nito Provenzano Tomas Bivort Juan.P Ceraso Santiago Alduncin Juan.P Anderson Lucas Magnasco Joaquin Diaz Luzzi Felipe Martignone Tomas Corneille Honours Nacional de Clubes (1): 2002 Torneo de la URBA (6): 1989, 1990, 1991, 1992, 2001, 2018 See also Buenos Aires English High School Alumni Athletic Club References External links Rugby clubs established in 1951 A 1951 establishments in Argentina

Players Current roster As of January 2018: Federico Lucca Gaspar Baldunciel Guido Cambareri Iñaki Etchegaray Bernardo Quaranta Tobias Moyano Mariano Romanini Santiago Montagner Tomas Passerotti Lucas Frana Luca Sabato Franco Batezzatti Franco Sabato Rafael Desanto Nito Provenzano Tomas Bivort Juan.P Ceraso Santiago Alduncin Juan.P Anderson Lucas Magnasco Joaquin Diaz Luzzi Felipe Martignone Tomas Corneille Honours Nacional de Clubes (1): 2002 Torneo de la URBA (6): 1989, 1990, 1991, 1992, 2001, 2018 See also Buenos Aires English High School Alumni Athletic Club References External links Rugby clubs established in 1951 A 1951 establishments in Argentina

Axiom An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or fit' or 'that which commends itself as evident'. The term has subtle differences in definition when used in the context of different fields of study. As defined in classic philosophy, an axiom is a statement that is so evident or well-established, that it is accepted without controversy or question. As used in modern logic, an axiom is a premise or starting point for reasoning. As used in mathematics, the term axiom is used in two related but distinguishable senses: "logical axioms" and "non-logical axioms". Logical axioms are usually statements that are taken to be true within the system of logic they define and are often shown in symbolic form (e.g., (A and B) implies A), while non-logical axioms (e.g., ) are actually substantive assertions about the elements of the domain of a specific mathematical theory (such as arithmetic). When used in the latter sense, "axiom", "postulate", and "assumption" may be used interchangeably. In most cases, a non-logical axiom is simply a formal logical expression used in deduction to build a mathematical theory, and might or might not be self-evident in nature (e.g., parallel postulate in Euclidean geometry). To axiomatize a system of knowledge is to show that its claims can be derived from a small, well-understood set of sentences (the axioms), and there may be multiple ways to axiomatize a given mathematical domain. Any axiom is a statement that serves as a starting point from which other statements are logically derived. Whether it is meaningful (and, if so, what it means) for an axiom to be "true" is a subject of debate in the philosophy of mathematics. Etymology The word axiom comes from the Greek word (axíōma), a verbal noun from the verb (axioein), meaning "to deem worthy", but also "to require", which in turn comes from (áxios), meaning "being in balance", and hence "having (the same) value (as)", "worthy", "proper". Among the ancient Greek philosophers an axiom was a claim which could be seen to be self-evidently true without any need for proof. The root meaning of the word postulate is to "demand"; for instance, Euclid demands that one agree that some things can be done (e.g., any two points can be joined by a straight line). Ancient geometers maintained some distinction between axioms and postulates. While commenting on Euclid's books, Proclus remarks that "Geminus held that this [4th] Postulate should not be classed as a postulate but as an axiom, since it does not, like the first three Postulates, assert the possibility of some construction but expresses an essential property." Boethius translated 'postulate' as petitio and called the axioms notiones communes but in later manuscripts this usage was not always strictly kept.

Axiom An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or fit' or 'that which commends itself as evident'. The term has subtle differences in definition when used in the context of different fields of study. As defined in classic philosophy, an axiom is a statement that is so evident or well-established, that it is accepted without controversy or question. As used in modern logic, an axiom is a premise or starting point for reasoning. As used in mathematics, the term axiom is used in two related but distinguishable senses: "logical axioms" and "non-logical axioms". Logical axioms are usually statements that are taken to be true within the system of logic they define and are often shown in symbolic form (e.g., (A and B) implies A), while non-logical axioms (e.g., ) are actually substantive assertions about the elements of the domain of a specific mathematical theory (such as arithmetic). When used in the latter sense, "axiom", "postulate", and "assumption" may be used interchangeably. In most cases, a non-logical axiom is simply a formal logical expression used in deduction to build a mathematical theory, and might or might not be self-evident in nature (e.g., parallel postulate in Euclidean geometry). To axiomatize a system of knowledge is to show that its claims can be derived from a small, well-understood set of sentences (the axioms), and there may be multiple ways to axiomatize a given mathematical domain. Any axiom is a statement that serves as a starting point from which other statements are logically derived. Whether it is meaningful (and, if so, what it means) for an axiom to be "true" is a subject of debate in the philosophy of mathematics. Etymology The word axiom comes from the Greek word (axíōma), a verbal noun from the verb (axioein), meaning "to deem worthy", but also "to require", which in turn comes from (áxios), meaning "being in balance", and hence "having (the same) value (as)", "worthy", "proper". Among the ancient Greek philosophers an axiom was a claim which could be seen to be self-evidently true without any need for proof. The root meaning of the word postulate is to "demand"; for instance, Euclid demands that one agree that some things can be done (e.g., any two points can be joined by a straight line). Ancient geometers maintained some distinction between axioms and postulates. While commenting on Euclid's books, Proclus remarks that "Geminus held that this [4th] Postulate should not be classed as a postulate but as an axiom, since it does not, like the first three Postulates, assert the possibility of some construction but expresses an essential property." Boethius translated 'postulate' as petitio and called the axioms notiones communes but in later manuscripts this usage was not always strictly kept.

Historical development Early Greeks The logico-deductive method whereby conclusions (new knowledge) follow from premises (old knowledge) through the application of sound arguments (syllogisms, rules of inference) was developed by the ancient Greeks, and has become the core principle of modern mathematics. Tautologies excluded, nothing can be deduced if nothing is assumed. Axioms and postulates are thus the basic assumptions underlying a given body of deductive knowledge. They are accepted without demonstration. All other assertions (theorems, in the case of mathematics) must be proven with the aid of these basic assumptions. However, the interpretation of mathematical knowledge has changed from ancient times to the modern, and consequently the terms axiom and postulate hold a slightly different meaning for the present day mathematician, than they did for Aristotle and Euclid. The ancient Greeks considered geometry as just one of several sciences, and held the theorems of geometry on par with scientific facts. As such, they developed and used the logico-deductive method as a means of avoiding error, and for structuring and communicating knowledge. Aristotle's posterior analytics is a definitive exposition of the classical view. An "axiom", in classical terminology, referred to a self-evident assumption common to many branches of science. A good example would be the assertion that When an equal amount is taken from equals, an equal amount results. At the foundation of the various sciences lay certain additional hypotheses that were accepted without proof. Such a hypothesis was termed a postulate. While the axioms were common to many sciences, the postulates of each particular science were different. Their validity had to be established by means of real-world experience. Aristotle warns that the content of a science cannot be successfully communicated if the learner is in doubt about the truth of the postulates. The classical approach is well-illustrated by Euclid's Elements, where a list of postulates is given (common-sensical geometric facts drawn from our experience), followed by a list of "common notions" (very basic, self-evident assertions). Postulates It is possible to draw a straight line from any point to any other point. It is possible to extend a line segment continuously in both directions. It is possible to describe a circle with any center and any radius. It is true that all right angles are equal to one another. ("Parallel postulate") It is true that, if a straight line falling on two straight lines make the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, intersect on that side on which are the angles less than the two right angles. Common notions Things which are equal to the same thing are also equal to one another. If equals are added to equals, the wholes are equal. If equals are subtracted from equals, the remainders are equal. Things which coincide with one another are equal to one another. The whole is greater than the part.

Historical development Early Greeks The logico-deductive method whereby conclusions (new knowledge) follow from premises (old knowledge) through the application of sound arguments (syllogisms, rules of inference) was developed by the ancient Greeks, and has become the core principle of modern mathematics. Tautologies excluded, nothing can be deduced if nothing is assumed. Axioms and postulates are thus the basic assumptions underlying a given body of deductive knowledge. They are accepted without demonstration. All other assertions (theorems, in the case of mathematics) must be proven with the aid of these basic assumptions. However, the interpretation of mathematical knowledge has changed from ancient times to the modern, and consequently the terms axiom and postulate hold a slightly different meaning for the present day mathematician, than they did for Aristotle and Euclid. The ancient Greeks considered geometry as just one of several sciences, and held the theorems of geometry on par with scientific facts. As such, they developed and used the logico-deductive method as a means of avoiding error, and for structuring and communicating knowledge. Aristotle's posterior analytics is a definitive exposition of the classical view. An "axiom", in classical terminology, referred to a self-evident assumption common to many branches of science. A good example would be the assertion that When an equal amount is taken from equals, an equal amount results. At the foundation of the various sciences lay certain additional hypotheses that were accepted without proof. Such a hypothesis was termed a postulate. While the axioms were common to many sciences, the postulates of each particular science were different. Their validity had to be established by means of real-world experience. Aristotle warns that the content of a science cannot be successfully communicated if the learner is in doubt about the truth of the postulates. The classical approach is well-illustrated by Euclid's Elements, where a list of postulates is given (common-sensical geometric facts drawn from our experience), followed by a list of "common notions" (very basic, self-evident assertions). Postulates It is possible to draw a straight line from any point to any other point. It is possible to extend a line segment continuously in both directions. It is possible to describe a circle with any center and any radius. It is true that all right angles are equal to one another. ("Parallel postulate") It is true that, if a straight line falling on two straight lines make the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, intersect on that side on which are the angles less than the two right angles. Common notions Things which are equal to the same thing are also equal to one another. If equals are added to equals, the wholes are equal. If equals are subtracted from equals, the remainders are equal. Things which coincide with one another are equal to one another. The whole is greater than the part.

Historical development Early Greeks The logico-deductive method whereby conclusions (new knowledge) follow from premises (old knowledge) through the application of sound arguments (syllogisms, rules of inference) was developed by the ancient Greeks, and has become the core principle of modern mathematics. Tautologies excluded, nothing can be deduced if nothing is assumed. Axioms and postulates are thus the basic assumptions underlying a given body of deductive knowledge. They are accepted without demonstration. All other assertions (theorems, in the case of mathematics) must be proven with the aid of these basic assumptions. However, the interpretation of mathematical knowledge has changed from ancient times to the modern, and consequently the terms axiom and postulate hold a slightly different meaning for the present day mathematician, than they did for Aristotle and Euclid. The ancient Greeks considered geometry as just one of several sciences, and held the theorems of geometry on par with scientific facts. As such, they developed and used the logico-deductive method as a means of avoiding error, and for structuring and communicating knowledge. Aristotle's posterior analytics is a definitive exposition of the classical view. An "axiom", in classical terminology, referred to a self-evident assumption common to many branches of science. A good example would be the assertion that When an equal amount is taken from equals, an equal amount results. At the foundation of the various sciences lay certain additional hypotheses that were accepted without proof. Such a hypothesis was termed a postulate. While the axioms were common to many sciences, the postulates of each particular science were different. Their validity had to be established by means of real-world experience. Aristotle warns that the content of a science cannot be successfully communicated if the learner is in doubt about the truth of the postulates. The classical approach is well-illustrated by Euclid's Elements, where a list of postulates is given (common-sensical geometric facts drawn from our experience), followed by a list of "common notions" (very basic, self-evident assertions). Postulates It is possible to draw a straight line from any point to any other point. It is possible to extend a line segment continuously in both directions. It is possible to describe a circle with any center and any radius. It is true that all right angles are equal to one another. ("Parallel postulate") It is true that, if a straight line falling on two straight lines make the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, intersect on that side on which are the angles less than the two right angles. Common notions Things which are equal to the same thing are also equal to one another. If equals are added to equals, the wholes are equal. If equals are subtracted from equals, the remainders are equal. Things which coincide with one another are equal to one another. The whole is greater than the part.

Modern development A lesson learned by mathematics in the last 150 years is that it is useful to strip the meaning away from the mathematical assertions (axioms, postulates, propositions, theorems) and definitions. One must concede the need for primitive notions, or undefined terms or concepts, in any study. Such abstraction or formalization makes mathematical knowledge more general, capable of multiple different meanings, and therefore useful in multiple contexts. Alessandro Padoa, Mario Pieri, and Giuseppe Peano were pioneers in this movement. Structuralist mathematics goes further, and develops theories and axioms (e.g. field theory, group theory, topology, vector spaces) without any particular application in mind. The distinction between an "axiom" and a "postulate" disappears. The postulates of Euclid are profitably motivated by saying that they lead to a great wealth of geometric facts. The truth of these complicated facts rests on the acceptance of the basic hypotheses. However, by throwing out Euclid's fifth postulate, one can get theories that have meaning in wider contexts (e.g., hyperbolic geometry). As such, one must simply be prepared to use labels such as "line" and "parallel" with greater flexibility. The development of hyperbolic geometry taught mathematicians that it is useful to regard postulates as purely formal statements, and not as facts based on experience. When mathematicians employ the field axioms, the intentions are even more abstract. The propositions of field theory do not concern any one particular application; the mathematician now works in complete abstraction. There are many examples of fields; field theory gives correct knowledge about them all. It is not correct to say that the axioms of field theory are "propositions that are regarded as true without proof." Rather, the field axioms are a set of constraints. If any given system of addition and multiplication satisfies these constraints, then one is in a position to instantly know a great deal of extra information about this system. Modern mathematics formalizes its foundations to such an extent that mathematical theories can be regarded as mathematical objects, and mathematics itself can be regarded as a branch of logic. Frege, Russell, Poincaré, Hilbert, and Gödel are some of the key figures in this development. Another lesson learned in modern mathematics is to examine purported proofs carefully for hidden assumptions. In the modern understanding, a set of axioms is any collection of formally stated assertions from which other formally stated assertions follow – by the application of certain well-defined rules. In this view, logic becomes just another formal system. A set of axioms should be consistent; it should be impossible to derive a contradiction from the axioms. A set of axioms should also be non-redundant; an assertion that can be deduced from other axioms need not be regarded as an axiom. It was the early hope of modern logicians that various branches of mathematics, perhaps all of mathematics, could be derived from a consistent collection of basic axioms.

Modern development A lesson learned by mathematics in the last 150 years is that it is useful to strip the meaning away from the mathematical assertions (axioms, postulates, propositions, theorems) and definitions. One must concede the need for primitive notions, or undefined terms or concepts, in any study. Such abstraction or formalization makes mathematical knowledge more general, capable of multiple different meanings, and therefore useful in multiple contexts. Alessandro Padoa, Mario Pieri, and Giuseppe Peano were pioneers in this movement. Structuralist mathematics goes further, and develops theories and axioms (e.g. field theory, group theory, topology, vector spaces) without any particular application in mind. The distinction between an "axiom" and a "postulate" disappears. The postulates of Euclid are profitably motivated by saying that they lead to a great wealth of geometric facts. The truth of these complicated facts rests on the acceptance of the basic hypotheses. However, by throwing out Euclid's fifth postulate, one can get theories that have meaning in wider contexts (e.g., hyperbolic geometry). As such, one must simply be prepared to use labels such as "line" and "parallel" with greater flexibility. The development of hyperbolic geometry taught mathematicians that it is useful to regard postulates as purely formal statements, and not as facts based on experience. When mathematicians employ the field axioms, the intentions are even more abstract. The propositions of field theory do not concern any one particular application; the mathematician now works in complete abstraction. There are many examples of fields; field theory gives correct knowledge about them all. It is not correct to say that the axioms of field theory are "propositions that are regarded as true without proof." Rather, the field axioms are a set of constraints. If any given system of addition and multiplication satisfies these constraints, then one is in a position to instantly know a great deal of extra information about this system. Modern mathematics formalizes its foundations to such an extent that mathematical theories can be regarded as mathematical objects, and mathematics itself can be regarded as a branch of logic. Frege, Russell, Poincaré, Hilbert, and Gödel are some of the key figures in this development. Another lesson learned in modern mathematics is to examine purported proofs carefully for hidden assumptions. In the modern understanding, a set of axioms is any collection of formally stated assertions from which other formally stated assertions follow – by the application of certain well-defined rules. In this view, logic becomes just another formal system. A set of axioms should be consistent; it should be impossible to derive a contradiction from the axioms. A set of axioms should also be non-redundant; an assertion that can be deduced from other axioms need not be regarded as an axiom. It was the early hope of modern logicians that various branches of mathematics, perhaps all of mathematics, could be derived from a consistent collection of basic axioms.

Modern development A lesson learned by mathematics in the last 150 years is that it is useful to strip the meaning away from the mathematical assertions (axioms, postulates, propositions, theorems) and definitions. One must concede the need for primitive notions, or undefined terms or concepts, in any study. Such abstraction or formalization makes mathematical knowledge more general, capable of multiple different meanings, and therefore useful in multiple contexts. Alessandro Padoa, Mario Pieri, and Giuseppe Peano were pioneers in this movement. Structuralist mathematics goes further, and develops theories and axioms (e.g. field theory, group theory, topology, vector spaces) without any particular application in mind. The distinction between an "axiom" and a "postulate" disappears. The postulates of Euclid are profitably motivated by saying that they lead to a great wealth of geometric facts. The truth of these complicated facts rests on the acceptance of the basic hypotheses. However, by throwing out Euclid's fifth postulate, one can get theories that have meaning in wider contexts (e.g., hyperbolic geometry). As such, one must simply be prepared to use labels such as "line" and "parallel" with greater flexibility. The development of hyperbolic geometry taught mathematicians that it is useful to regard postulates as purely formal statements, and not as facts based on experience. When mathematicians employ the field axioms, the intentions are even more abstract. The propositions of field theory do not concern any one particular application; the mathematician now works in complete abstraction. There are many examples of fields; field theory gives correct knowledge about them all. It is not correct to say that the axioms of field theory are "propositions that are regarded as true without proof." Rather, the field axioms are a set of constraints. If any given system of addition and multiplication satisfies these constraints, then one is in a position to instantly know a great deal of extra information about this system. Modern mathematics formalizes its foundations to such an extent that mathematical theories can be regarded as mathematical objects, and mathematics itself can be regarded as a branch of logic. Frege, Russell, Poincaré, Hilbert, and Gödel are some of the key figures in this development. Another lesson learned in modern mathematics is to examine purported proofs carefully for hidden assumptions. In the modern understanding, a set of axioms is any collection of formally stated assertions from which other formally stated assertions follow – by the application of certain well-defined rules. In this view, logic becomes just another formal system. A set of axioms should be consistent; it should be impossible to derive a contradiction from the axioms. A set of axioms should also be non-redundant; an assertion that can be deduced from other axioms need not be regarded as an axiom. It was the early hope of modern logicians that various branches of mathematics, perhaps all of mathematics, could be derived from a consistent collection of basic axioms.

An early success of the formalist program was Hilbert's formalization of Euclidean geometry, and the related demonstration of the consistency of those axioms. In a wider context, there was an attempt to base all of mathematics on Cantor's set theory. Here, the emergence of Russell's paradox and similar antinomies of naïve set theory raised the possibility that any such system could turn out to be inconsistent. The formalist project suffered a decisive setback, when in 1931 Gödel showed that it is possible, for any sufficiently large set of axioms (Peano's axioms, for example) to construct a statement whose truth is independent of that set of axioms. As a corollary, Gödel proved that the consistency of a theory like Peano arithmetic is an unprovable assertion within the scope of that theory. It is reasonable to believe in the consistency of Peano arithmetic because it is satisfied by the system of natural numbers, an infinite but intuitively accessible formal system. However, at present, there is no known way of demonstrating the consistency of the modern Zermelo–Fraenkel axioms for set theory. Furthermore, using techniques of forcing (Cohen) one can show that the continuum hypothesis (Cantor) is independent of the Zermelo–Fraenkel axioms. Thus, even this very general set of axioms cannot be regarded as the definitive foundation for mathematics. Other sciences Experimental sciences - as opposed to mathematics and logic - also have general founding assertions from which a deductive reasoning can be built so as to express propositions that predict properties - either still general or much more specialized to a specific experimental context. For instance, Newton's laws in classical mechanics, Maxwell's equations in classical electromagnetism, Einstein's equation in general relativity, Mandel's laws of genetics, Darwin's Natural selection law, etc. These founding assertions are usually called principles or postulates so as to distinguish from mathematical axioms. As a matter of facts, the role of axioms in mathematics and postulates in experimental sciences is different. In mathematics one neither "proves" nor "disproves" an axiom. A set of mathematical axioms gives a set of rules that fix a conceptual realm, in which the theorems logically follow. In contrast, in experimental sciences, a set of postulates shall allow deducing results that match or do not match experimental results. If postulates do not allow deducing experimental predictions, they do not set a scientific conceptual framework and have to be completed or made more accurate. If the postulates allow deducing predictions of experimental results, the comparison with experiments allows falsifying (falsified) the theory that the postulates install. A theory is considered valid as long as it has not been falsified. Now, the transition between the mathematical axioms and scientific postulates is always slightly blurred, especially in physics. This is due to the heavy use of mathematical tools to support the physical theories. For instance, the introduction of Newton's laws rarely establishes as a prerequisite neither Euclidian geometry or differential calculus that they imply.

An early success of the formalist program was Hilbert's formalization of Euclidean geometry, and the related demonstration of the consistency of those axioms. In a wider context, there was an attempt to base all of mathematics on Cantor's set theory. Here, the emergence of Russell's paradox and similar antinomies of naïve set theory raised the possibility that any such system could turn out to be inconsistent. The formalist project suffered a decisive setback, when in 1931 Gödel showed that it is possible, for any sufficiently large set of axioms (Peano's axioms, for example) to construct a statement whose truth is independent of that set of axioms. As a corollary, Gödel proved that the consistency of a theory like Peano arithmetic is an unprovable assertion within the scope of that theory. It is reasonable to believe in the consistency of Peano arithmetic because it is satisfied by the system of natural numbers, an infinite but intuitively accessible formal system. However, at present, there is no known way of demonstrating the consistency of the modern Zermelo–Fraenkel axioms for set theory. Furthermore, using techniques of forcing (Cohen) one can show that the continuum hypothesis (Cantor) is independent of the Zermelo–Fraenkel axioms. Thus, even this very general set of axioms cannot be regarded as the definitive foundation for mathematics. Other sciences Experimental sciences - as opposed to mathematics and logic - also have general founding assertions from which a deductive reasoning can be built so as to express propositions that predict properties - either still general or much more specialized to a specific experimental context. For instance, Newton's laws in classical mechanics, Maxwell's equations in classical electromagnetism, Einstein's equation in general relativity, Mandel's laws of genetics, Darwin's Natural selection law, etc. These founding assertions are usually called principles or postulates so as to distinguish from mathematical axioms. As a matter of facts, the role of axioms in mathematics and postulates in experimental sciences is different. In mathematics one neither "proves" nor "disproves" an axiom. A set of mathematical axioms gives a set of rules that fix a conceptual realm, in which the theorems logically follow. In contrast, in experimental sciences, a set of postulates shall allow deducing results that match or do not match experimental results. If postulates do not allow deducing experimental predictions, they do not set a scientific conceptual framework and have to be completed or made more accurate. If the postulates allow deducing predictions of experimental results, the comparison with experiments allows falsifying (falsified) the theory that the postulates install. A theory is considered valid as long as it has not been falsified. Now, the transition between the mathematical axioms and scientific postulates is always slightly blurred, especially in physics. This is due to the heavy use of mathematical tools to support the physical theories. For instance, the introduction of Newton's laws rarely establishes as a prerequisite neither Euclidian geometry or differential calculus that they imply.

An early success of the formalist program was Hilbert's formalization of Euclidean geometry, and the related demonstration of the consistency of those axioms. In a wider context, there was an attempt to base all of mathematics on Cantor's set theory. Here, the emergence of Russell's paradox and similar antinomies of naïve set theory raised the possibility that any such system could turn out to be inconsistent. The formalist project suffered a decisive setback, when in 1931 Gödel showed that it is possible, for any sufficiently large set of axioms (Peano's axioms, for example) to construct a statement whose truth is independent of that set of axioms. As a corollary, Gödel proved that the consistency of a theory like Peano arithmetic is an unprovable assertion within the scope of that theory. It is reasonable to believe in the consistency of Peano arithmetic because it is satisfied by the system of natural numbers, an infinite but intuitively accessible formal system. However, at present, there is no known way of demonstrating the consistency of the modern Zermelo–Fraenkel axioms for set theory. Furthermore, using techniques of forcing (Cohen) one can show that the continuum hypothesis (Cantor) is independent of the Zermelo–Fraenkel axioms. Thus, even this very general set of axioms cannot be regarded as the definitive foundation for mathematics. Other sciences Experimental sciences - as opposed to mathematics and logic - also have general founding assertions from which a deductive reasoning can be built so as to express propositions that predict properties - either still general or much more specialized to a specific experimental context. For instance, Newton's laws in classical mechanics, Maxwell's equations in classical electromagnetism, Einstein's equation in general relativity, Mandel's laws of genetics, Darwin's Natural selection law, etc. These founding assertions are usually called principles or postulates so as to distinguish from mathematical axioms. As a matter of facts, the role of axioms in mathematics and postulates in experimental sciences is different. In mathematics one neither "proves" nor "disproves" an axiom. A set of mathematical axioms gives a set of rules that fix a conceptual realm, in which the theorems logically follow. In contrast, in experimental sciences, a set of postulates shall allow deducing results that match or do not match experimental results. If postulates do not allow deducing experimental predictions, they do not set a scientific conceptual framework and have to be completed or made more accurate. If the postulates allow deducing predictions of experimental results, the comparison with experiments allows falsifying (falsified) the theory that the postulates install. A theory is considered valid as long as it has not been falsified. Now, the transition between the mathematical axioms and scientific postulates is always slightly blurred, especially in physics. This is due to the heavy use of mathematical tools to support the physical theories. For instance, the introduction of Newton's laws rarely establishes as a prerequisite neither Euclidian geometry or differential calculus that they imply.

It became more apparent when Albert Einstein first introduced special relativity where the invariant quantity is no more the Euclidian length (defined as ) > but the Minkowski spacetime interval (defined as ), and then general relativity where flat Minkowskian geometry is replaced with pseudo-Riemannian geometry on curved manifolds. In quantum physics, two sets of postulates have coexisted for some time, which provide a very nice example of falsification. The 'Copenhagen school' (Niels Bohr, Werner Heisenberg, Max Born) developed an operational approach with a complete mathematical formalism that involves the description of quantum system by vectors ('states') in a separable Hilbert space, and physical quantities as linear operators that act in this Hilbert space. This approach is fully falsifiable and has so far produced the most accurate predictions in physics. But it has the unsatisfactory aspect of not allowing answers to questions one would naturally ask. For this reason, another 'hidden variables' approach was developed for some time by Albert Einstein, Erwin Schrödinger, David Bohm. It was created so as to try to give deterministic explanation to phenomena such as entanglement. This approach assumed that the Copenhagen school description was not complete, and postulated that some yet unknown variable was to be added to the theory so as to allow answering some of the questions it does not answer (the founding elements of which were discussed as the EPR paradox in 1935). Taking this ideas seriously, John Bell derived in 1964 a prediction that would lead to different experimental results (Bell's inequalities) in the Copenhagen and the Hidden variable case. The experiment was conducted first by Alain Aspect in the early 1980's, and the result excluded the simple hidden variable approach (sophisticated hidden variables could still exist but their properties would still be more disturbing than the problems they try to solve). This does not mean that the conceptual framework of quantum physics can be considered as complete now, since some open questions still exist (the limit between the quantum and classical realms, what happens during a quantum measurement, what happens in a completely closed quantum system such as the universe itself, etc). Mathematical logic In the field of mathematical logic, a clear distinction is made between two notions of axioms: logical and non-logical (somewhat similar to the ancient distinction between "axioms" and "postulates" respectively). Logical axioms These are certain formulas in a formal language that are universally valid, that is, formulas that are satisfied by every assignment of values. Usually one takes as logical axioms at least some minimal set of tautologies that is sufficient for proving all tautologies in the language; in the case of predicate logic more logical axioms than that are required, in order to prove logical truths that are not tautologies in the strict sense.

It became more apparent when Albert Einstein first introduced special relativity where the invariant quantity is no more the Euclidian length (defined as ) > but the Minkowski spacetime interval (defined as ), and then general relativity where flat Minkowskian geometry is replaced with pseudo-Riemannian geometry on curved manifolds. In quantum physics, two sets of postulates have coexisted for some time, which provide a very nice example of falsification. The 'Copenhagen school' (Niels Bohr, Werner Heisenberg, Max Born) developed an operational approach with a complete mathematical formalism that involves the description of quantum system by vectors ('states') in a separable Hilbert space, and physical quantities as linear operators that act in this Hilbert space. This approach is fully falsifiable and has so far produced the most accurate predictions in physics. But it has the unsatisfactory aspect of not allowing answers to questions one would naturally ask. For this reason, another 'hidden variables' approach was developed for some time by Albert Einstein, Erwin Schrödinger, David Bohm. It was created so as to try to give deterministic explanation to phenomena such as entanglement. This approach assumed that the Copenhagen school description was not complete, and postulated that some yet unknown variable was to be added to the theory so as to allow answering some of the questions it does not answer (the founding elements of which were discussed as the EPR paradox in 1935). Taking this ideas seriously, John Bell derived in 1964 a prediction that would lead to different experimental results (Bell's inequalities) in the Copenhagen and the Hidden variable case. The experiment was conducted first by Alain Aspect in the early 1980's, and the result excluded the simple hidden variable approach (sophisticated hidden variables could still exist but their properties would still be more disturbing than the problems they try to solve). This does not mean that the conceptual framework of quantum physics can be considered as complete now, since some open questions still exist (the limit between the quantum and classical realms, what happens during a quantum measurement, what happens in a completely closed quantum system such as the universe itself, etc). Mathematical logic In the field of mathematical logic, a clear distinction is made between two notions of axioms: logical and non-logical (somewhat similar to the ancient distinction between "axioms" and "postulates" respectively). Logical axioms These are certain formulas in a formal language that are universally valid, that is, formulas that are satisfied by every assignment of values. Usually one takes as logical axioms at least some minimal set of tautologies that is sufficient for proving all tautologies in the language; in the case of predicate logic more logical axioms than that are required, in order to prove logical truths that are not tautologies in the strict sense.

It became more apparent when Albert Einstein first introduced special relativity where the invariant quantity is no more the Euclidian length (defined as ) > but the Minkowski spacetime interval (defined as ), and then general relativity where flat Minkowskian geometry is replaced with pseudo-Riemannian geometry on curved manifolds. In quantum physics, two sets of postulates have coexisted for some time, which provide a very nice example of falsification. The 'Copenhagen school' (Niels Bohr, Werner Heisenberg, Max Born) developed an operational approach with a complete mathematical formalism that involves the description of quantum system by vectors ('states') in a separable Hilbert space, and physical quantities as linear operators that act in this Hilbert space. This approach is fully falsifiable and has so far produced the most accurate predictions in physics. But it has the unsatisfactory aspect of not allowing answers to questions one would naturally ask. For this reason, another 'hidden variables' approach was developed for some time by Albert Einstein, Erwin Schrödinger, David Bohm. It was created so as to try to give deterministic explanation to phenomena such as entanglement. This approach assumed that the Copenhagen school description was not complete, and postulated that some yet unknown variable was to be added to the theory so as to allow answering some of the questions it does not answer (the founding elements of which were discussed as the EPR paradox in 1935). Taking this ideas seriously, John Bell derived in 1964 a prediction that would lead to different experimental results (Bell's inequalities) in the Copenhagen and the Hidden variable case. The experiment was conducted first by Alain Aspect in the early 1980's, and the result excluded the simple hidden variable approach (sophisticated hidden variables could still exist but their properties would still be more disturbing than the problems they try to solve). This does not mean that the conceptual framework of quantum physics can be considered as complete now, since some open questions still exist (the limit between the quantum and classical realms, what happens during a quantum measurement, what happens in a completely closed quantum system such as the universe itself, etc). Mathematical logic In the field of mathematical logic, a clear distinction is made between two notions of axioms: logical and non-logical (somewhat similar to the ancient distinction between "axioms" and "postulates" respectively). Logical axioms These are certain formulas in a formal language that are universally valid, that is, formulas that are satisfied by every assignment of values. Usually one takes as logical axioms at least some minimal set of tautologies that is sufficient for proving all tautologies in the language; in the case of predicate logic more logical axioms than that are required, in order to prove logical truths that are not tautologies in the strict sense.

Examples Propositional logic In propositional logic it is common to take as logical axioms all formulae of the following forms, where , , and can be any formulae of the language and where the included primitive connectives are only "" for negation of the immediately following proposition and "" for implication from antecedent to consequent propositions: Each of these patterns is an axiom schema, a rule for generating an infinite number of axioms. For example, if , , and are propositional variables, then and are both instances of axiom schema 1, and hence are axioms. It can be shown that with only these three axiom schemata and modus ponens, one can prove all tautologies of the propositional calculus. It can also be shown that no pair of these schemata is sufficient for proving all tautologies with modus ponens. Other axiom schemata involving the same or different sets of primitive connectives can be alternatively constructed. These axiom schemata are also used in the predicate calculus, but additional logical axioms are needed to include a quantifier in the calculus. First-order logic Axiom of Equality. Let be a first-order language. For each variable , the formula is universally valid. This means that, for any variable symbol the formula can be regarded as an axiom. Also, in this example, for this not to fall into vagueness and a never-ending series of "primitive notions", either a precise notion of what we mean by (or, for that matter, "to be equal") has to be well established first, or a purely formal and syntactical usage of the symbol has to be enforced, only regarding it as a string and only a string of symbols, and mathematical logic does indeed do that. Another, more interesting example axiom scheme, is that which provides us with what is known as Universal Instantiation: Axiom scheme for Universal Instantiation. Given a formula in a first-order language , a variable and a term that is substitutable for in , the formula is universally valid. Where the symbol stands for the formula with the term substituted for . (See Substitution of variables.) In informal terms, this example allows us to state that, if we know that a certain property holds for every and that stands for a particular object in our structure, then we should be able to claim . Again, we are claiming that the formula is valid, that is, we must be able to give a "proof" of this fact, or more properly speaking, a metaproof. These examples are metatheorems of our theory of mathematical logic since we are dealing with the very concept of proof itself. Aside from this, we can also have Existential Generalization: Axiom scheme for Existential Generalization. Given a formula in a first-order language , a variable and a term that is substitutable for in , the formula is universally valid. Non-logical axioms Non-logical axioms are formulas that play the role of theory-specific assumptions.

Examples Propositional logic In propositional logic it is common to take as logical axioms all formulae of the following forms, where , , and can be any formulae of the language and where the included primitive connectives are only "" for negation of the immediately following proposition and "" for implication from antecedent to consequent propositions: Each of these patterns is an axiom schema, a rule for generating an infinite number of axioms. For example, if , , and are propositional variables, then and are both instances of axiom schema 1, and hence are axioms. It can be shown that with only these three axiom schemata and modus ponens, one can prove all tautologies of the propositional calculus. It can also be shown that no pair of these schemata is sufficient for proving all tautologies with modus ponens. Other axiom schemata involving the same or different sets of primitive connectives can be alternatively constructed. These axiom schemata are also used in the predicate calculus, but additional logical axioms are needed to include a quantifier in the calculus. First-order logic Axiom of Equality. Let be a first-order language. For each variable , the formula is universally valid. This means that, for any variable symbol the formula can be regarded as an axiom. Also, in this example, for this not to fall into vagueness and a never-ending series of "primitive notions", either a precise notion of what we mean by (or, for that matter, "to be equal") has to be well established first, or a purely formal and syntactical usage of the symbol has to be enforced, only regarding it as a string and only a string of symbols, and mathematical logic does indeed do that. Another, more interesting example axiom scheme, is that which provides us with what is known as Universal Instantiation: Axiom scheme for Universal Instantiation. Given a formula in a first-order language , a variable and a term that is substitutable for in , the formula is universally valid. Where the symbol stands for the formula with the term substituted for . (See Substitution of variables.) In informal terms, this example allows us to state that, if we know that a certain property holds for every and that stands for a particular object in our structure, then we should be able to claim . Again, we are claiming that the formula is valid, that is, we must be able to give a "proof" of this fact, or more properly speaking, a metaproof. These examples are metatheorems of our theory of mathematical logic since we are dealing with the very concept of proof itself. Aside from this, we can also have Existential Generalization: Axiom scheme for Existential Generalization. Given a formula in a first-order language , a variable and a term that is substitutable for in , the formula is universally valid. Non-logical axioms Non-logical axioms are formulas that play the role of theory-specific assumptions.

Examples Propositional logic In propositional logic it is common to take as logical axioms all formulae of the following forms, where , , and can be any formulae of the language and where the included primitive connectives are only "" for negation of the immediately following proposition and "" for implication from antecedent to consequent propositions: Each of these patterns is an axiom schema, a rule for generating an infinite number of axioms. For example, if , , and are propositional variables, then and are both instances of axiom schema 1, and hence are axioms. It can be shown that with only these three axiom schemata and modus ponens, one can prove all tautologies of the propositional calculus. It can also be shown that no pair of these schemata is sufficient for proving all tautologies with modus ponens. Other axiom schemata involving the same or different sets of primitive connectives can be alternatively constructed. These axiom schemata are also used in the predicate calculus, but additional logical axioms are needed to include a quantifier in the calculus. First-order logic Axiom of Equality. Let be a first-order language. For each variable , the formula is universally valid. This means that, for any variable symbol the formula can be regarded as an axiom. Also, in this example, for this not to fall into vagueness and a never-ending series of "primitive notions", either a precise notion of what we mean by (or, for that matter, "to be equal") has to be well established first, or a purely formal and syntactical usage of the symbol has to be enforced, only regarding it as a string and only a string of symbols, and mathematical logic does indeed do that. Another, more interesting example axiom scheme, is that which provides us with what is known as Universal Instantiation: Axiom scheme for Universal Instantiation. Given a formula in a first-order language , a variable and a term that is substitutable for in , the formula is universally valid. Where the symbol stands for the formula with the term substituted for . (See Substitution of variables.) In informal terms, this example allows us to state that, if we know that a certain property holds for every and that stands for a particular object in our structure, then we should be able to claim . Again, we are claiming that the formula is valid, that is, we must be able to give a "proof" of this fact, or more properly speaking, a metaproof. These examples are metatheorems of our theory of mathematical logic since we are dealing with the very concept of proof itself. Aside from this, we can also have Existential Generalization: Axiom scheme for Existential Generalization. Given a formula in a first-order language , a variable and a term that is substitutable for in , the formula is universally valid. Non-logical axioms Non-logical axioms are formulas that play the role of theory-specific assumptions.

Reasoning about two different structures, for example, the natural numbers and the integers, may involve the same logical axioms; the non-logical axioms aim to capture what is special about a particular structure (or set of structures, such as groups). Thus non-logical axioms, unlike logical axioms, are not tautologies. Another name for a non-logical axiom is postulate. Almost every modern mathematical theory starts from a given set of non-logical axioms, and it was thought that in principle every theory could be axiomatized in this way and formalized down to the bare language of logical formulas. Non-logical axioms are often simply referred to as axioms in mathematical discourse. This does not mean that it is claimed that they are true in some absolute sense. For example, in some groups, the group operation is commutative, and this can be asserted with the introduction of an additional axiom, but without this axiom, we can do quite well developing (the more general) group theory, and we can even take its negation as an axiom for the study of non-commutative groups. Thus, an axiom is an elementary basis for a formal logic system that together with the rules of inference define a deductive system. Examples This section gives examples of mathematical theories that are developed entirely from a set of non-logical axioms (axioms, henceforth). A rigorous treatment of any of these topics begins with a specification of these axioms. Basic theories, such as arithmetic, real analysis and complex analysis are often introduced non-axiomatically, but implicitly or explicitly there is generally an assumption that the axioms being used are the axioms of Zermelo–Fraenkel set theory with choice, abbreviated ZFC, or some very similar system of axiomatic set theory like Von Neumann–Bernays–Gödel set theory, a conservative extension of ZFC. Sometimes slightly stronger theories such as Morse–Kelley set theory or set theory with a strongly inaccessible cardinal allowing the use of a Grothendieck universe is used, but in fact, most mathematicians can actually prove all they need in systems weaker than ZFC, such as second-order arithmetic. The study of topology in mathematics extends all over through point set topology, algebraic topology, differential topology, and all the related paraphernalia, such as homology theory, homotopy theory. The development of abstract algebra brought with itself group theory, rings, fields, and Galois theory. This list could be expanded to include most fields of mathematics, including measure theory, ergodic theory, probability, representation theory, and differential geometry. Arithmetic The Peano axioms are the most widely used axiomatization of first-order arithmetic. They are a set of axioms strong enough to prove many important facts about number theory and they allowed Gödel to establish his famous second incompleteness theorem. We have a language where is a constant symbol and is a unary function and the following axioms: for any formula with one free variable. The standard structure is where is the set of natural numbers, is the successor function and is naturally interpreted as the number 0.

Reasoning about two different structures, for example, the natural numbers and the integers, may involve the same logical axioms; the non-logical axioms aim to capture what is special about a particular structure (or set of structures, such as groups). Thus non-logical axioms, unlike logical axioms, are not tautologies. Another name for a non-logical axiom is postulate. Almost every modern mathematical theory starts from a given set of non-logical axioms, and it was thought that in principle every theory could be axiomatized in this way and formalized down to the bare language of logical formulas. Non-logical axioms are often simply referred to as axioms in mathematical discourse. This does not mean that it is claimed that they are true in some absolute sense. For example, in some groups, the group operation is commutative, and this can be asserted with the introduction of an additional axiom, but without this axiom, we can do quite well developing (the more general) group theory, and we can even take its negation as an axiom for the study of non-commutative groups. Thus, an axiom is an elementary basis for a formal logic system that together with the rules of inference define a deductive system. Examples This section gives examples of mathematical theories that are developed entirely from a set of non-logical axioms (axioms, henceforth). A rigorous treatment of any of these topics begins with a specification of these axioms. Basic theories, such as arithmetic, real analysis and complex analysis are often introduced non-axiomatically, but implicitly or explicitly there is generally an assumption that the axioms being used are the axioms of Zermelo–Fraenkel set theory with choice, abbreviated ZFC, or some very similar system of axiomatic set theory like Von Neumann–Bernays–Gödel set theory, a conservative extension of ZFC. Sometimes slightly stronger theories such as Morse–Kelley set theory or set theory with a strongly inaccessible cardinal allowing the use of a Grothendieck universe is used, but in fact, most mathematicians can actually prove all they need in systems weaker than ZFC, such as second-order arithmetic. The study of topology in mathematics extends all over through point set topology, algebraic topology, differential topology, and all the related paraphernalia, such as homology theory, homotopy theory. The development of abstract algebra brought with itself group theory, rings, fields, and Galois theory. This list could be expanded to include most fields of mathematics, including measure theory, ergodic theory, probability, representation theory, and differential geometry. Arithmetic The Peano axioms are the most widely used axiomatization of first-order arithmetic. They are a set of axioms strong enough to prove many important facts about number theory and they allowed Gödel to establish his famous second incompleteness theorem. We have a language where is a constant symbol and is a unary function and the following axioms: for any formula with one free variable. The standard structure is where is the set of natural numbers, is the successor function and is naturally interpreted as the number 0.

Reasoning about two different structures, for example, the natural numbers and the integers, may involve the same logical axioms; the non-logical axioms aim to capture what is special about a particular structure (or set of structures, such as groups). Thus non-logical axioms, unlike logical axioms, are not tautologies. Another name for a non-logical axiom is postulate. Almost every modern mathematical theory starts from a given set of non-logical axioms, and it was thought that in principle every theory could be axiomatized in this way and formalized down to the bare language of logical formulas. Non-logical axioms are often simply referred to as axioms in mathematical discourse. This does not mean that it is claimed that they are true in some absolute sense. For example, in some groups, the group operation is commutative, and this can be asserted with the introduction of an additional axiom, but without this axiom, we can do quite well developing (the more general) group theory, and we can even take its negation as an axiom for the study of non-commutative groups. Thus, an axiom is an elementary basis for a formal logic system that together with the rules of inference define a deductive system. Examples This section gives examples of mathematical theories that are developed entirely from a set of non-logical axioms (axioms, henceforth). A rigorous treatment of any of these topics begins with a specification of these axioms. Basic theories, such as arithmetic, real analysis and complex analysis are often introduced non-axiomatically, but implicitly or explicitly there is generally an assumption that the axioms being used are the axioms of Zermelo–Fraenkel set theory with choice, abbreviated ZFC, or some very similar system of axiomatic set theory like Von Neumann–Bernays–Gödel set theory, a conservative extension of ZFC. Sometimes slightly stronger theories such as Morse–Kelley set theory or set theory with a strongly inaccessible cardinal allowing the use of a Grothendieck universe is used, but in fact, most mathematicians can actually prove all they need in systems weaker than ZFC, such as second-order arithmetic. The study of topology in mathematics extends all over through point set topology, algebraic topology, differential topology, and all the related paraphernalia, such as homology theory, homotopy theory. The development of abstract algebra brought with itself group theory, rings, fields, and Galois theory. This list could be expanded to include most fields of mathematics, including measure theory, ergodic theory, probability, representation theory, and differential geometry. Arithmetic The Peano axioms are the most widely used axiomatization of first-order arithmetic. They are a set of axioms strong enough to prove many important facts about number theory and they allowed Gödel to establish his famous second incompleteness theorem. We have a language where is a constant symbol and is a unary function and the following axioms: for any formula with one free variable. The standard structure is where is the set of natural numbers, is the successor function and is naturally interpreted as the number 0.

Euclidean geometry Probably the oldest, and most famous, list of axioms are the 4 + 1 Euclid's postulates of plane geometry. The axioms are referred to as "4 + 1" because for nearly two millennia the fifth (parallel) postulate ("through a point outside a line there is exactly one parallel") was suspected of being derivable from the first four. Ultimately, the fifth postulate was found to be independent of the first four. One can assume that exactly one parallel through a point outside a line exists, or that infinitely many exist. This choice gives us two alternative forms of geometry in which the interior angles of a triangle add up to exactly 180 degrees or less, respectively, and are known as Euclidean and hyperbolic geometries. If one also removes the second postulate ("a line can be extended indefinitely") then elliptic geometry arises, where there is no parallel through a point outside a line, and in which the interior angles of a triangle add up to more than 180 degrees. Real analysis The objectives of the study are within the domain of real numbers. The real numbers are uniquely picked out (up to isomorphism) by the properties of a Dedekind complete ordered field, meaning that any nonempty set of real numbers with an upper bound has a least upper bound. However, expressing these properties as axioms requires the use of second-order logic. The Löwenheim–Skolem theorems tell us that if we restrict ourselves to first-order logic, any axiom system for the reals admits other models, including both models that are smaller than the reals and models that are larger. Some of the latter are studied in non-standard analysis. Role in mathematical logic Deductive systems and completeness A deductive system consists of a set of logical axioms, a set of non-logical axioms, and a set of rules of inference. A desirable property of a deductive system is that it be complete. A system is said to be complete if, for all formulas , that is, for any statement that is a logical consequence of there actually exists a deduction of the statement from . This is sometimes expressed as "everything that is true is provable", but it must be understood that "true" here means "made true by the set of axioms", and not, for example, "true in the intended interpretation". Gödel's completeness theorem establishes the completeness of a certain commonly used type of deductive system. Note that "completeness" has a different meaning here than it does in the context of Gödel's first incompleteness theorem, which states that no recursive, consistent set of non-logical axioms of the Theory of Arithmetic is complete, in the sense that there will always exist an arithmetic statement such that neither nor can be proved from the given set of axioms. There is thus, on the one hand, the notion of completeness of a deductive system and on the other hand that of completeness of a set of non-logical axioms.

Euclidean geometry Probably the oldest, and most famous, list of axioms are the 4 + 1 Euclid's postulates of plane geometry. The axioms are referred to as "4 + 1" because for nearly two millennia the fifth (parallel) postulate ("through a point outside a line there is exactly one parallel") was suspected of being derivable from the first four. Ultimately, the fifth postulate was found to be independent of the first four. One can assume that exactly one parallel through a point outside a line exists, or that infinitely many exist. This choice gives us two alternative forms of geometry in which the interior angles of a triangle add up to exactly 180 degrees or less, respectively, and are known as Euclidean and hyperbolic geometries. If one also removes the second postulate ("a line can be extended indefinitely") then elliptic geometry arises, where there is no parallel through a point outside a line, and in which the interior angles of a triangle add up to more than 180 degrees. Real analysis The objectives of the study are within the domain of real numbers. The real numbers are uniquely picked out (up to isomorphism) by the properties of a Dedekind complete ordered field, meaning that any nonempty set of real numbers with an upper bound has a least upper bound. However, expressing these properties as axioms requires the use of second-order logic. The Löwenheim–Skolem theorems tell us that if we restrict ourselves to first-order logic, any axiom system for the reals admits other models, including both models that are smaller than the reals and models that are larger. Some of the latter are studied in non-standard analysis. Role in mathematical logic Deductive systems and completeness A deductive system consists of a set of logical axioms, a set of non-logical axioms, and a set of rules of inference. A desirable property of a deductive system is that it be complete. A system is said to be complete if, for all formulas , that is, for any statement that is a logical consequence of there actually exists a deduction of the statement from . This is sometimes expressed as "everything that is true is provable", but it must be understood that "true" here means "made true by the set of axioms", and not, for example, "true in the intended interpretation". Gödel's completeness theorem establishes the completeness of a certain commonly used type of deductive system. Note that "completeness" has a different meaning here than it does in the context of Gödel's first incompleteness theorem, which states that no recursive, consistent set of non-logical axioms of the Theory of Arithmetic is complete, in the sense that there will always exist an arithmetic statement such that neither nor can be proved from the given set of axioms. There is thus, on the one hand, the notion of completeness of a deductive system and on the other hand that of completeness of a set of non-logical axioms.

Euclidean geometry Probably the oldest, and most famous, list of axioms are the 4 + 1 Euclid's postulates of plane geometry. The axioms are referred to as "4 + 1" because for nearly two millennia the fifth (parallel) postulate ("through a point outside a line there is exactly one parallel") was suspected of being derivable from the first four. Ultimately, the fifth postulate was found to be independent of the first four. One can assume that exactly one parallel through a point outside a line exists, or that infinitely many exist. This choice gives us two alternative forms of geometry in which the interior angles of a triangle add up to exactly 180 degrees or less, respectively, and are known as Euclidean and hyperbolic geometries. If one also removes the second postulate ("a line can be extended indefinitely") then elliptic geometry arises, where there is no parallel through a point outside a line, and in which the interior angles of a triangle add up to more than 180 degrees. Real analysis The objectives of the study are within the domain of real numbers. The real numbers are uniquely picked out (up to isomorphism) by the properties of a Dedekind complete ordered field, meaning that any nonempty set of real numbers with an upper bound has a least upper bound. However, expressing these properties as axioms requires the use of second-order logic. The Löwenheim–Skolem theorems tell us that if we restrict ourselves to first-order logic, any axiom system for the reals admits other models, including both models that are smaller than the reals and models that are larger. Some of the latter are studied in non-standard analysis. Role in mathematical logic Deductive systems and completeness A deductive system consists of a set of logical axioms, a set of non-logical axioms, and a set of rules of inference. A desirable property of a deductive system is that it be complete. A system is said to be complete if, for all formulas , that is, for any statement that is a logical consequence of there actually exists a deduction of the statement from . This is sometimes expressed as "everything that is true is provable", but it must be understood that "true" here means "made true by the set of axioms", and not, for example, "true in the intended interpretation". Gödel's completeness theorem establishes the completeness of a certain commonly used type of deductive system. Note that "completeness" has a different meaning here than it does in the context of Gödel's first incompleteness theorem, which states that no recursive, consistent set of non-logical axioms of the Theory of Arithmetic is complete, in the sense that there will always exist an arithmetic statement such that neither nor can be proved from the given set of axioms. There is thus, on the one hand, the notion of completeness of a deductive system and on the other hand that of completeness of a set of non-logical axioms.

The completeness theorem and the incompleteness theorem, despite their names, do not contradict one another. Further discussion Early mathematicians regarded axiomatic geometry as a model of physical space, and obviously, there could only be one such model. The idea that alternative mathematical systems might exist was very troubling to mathematicians of the 19th century and the developers of systems such as Boolean algebra made elaborate efforts to derive them from traditional arithmetic. Galois showed just before his untimely death that these efforts were largely wasted. Ultimately, the abstract parallels between algebraic systems were seen to be more important than the details, and modern algebra was born. In the modern view, axioms may be any set of formulas, as long as they are not known to be inconsistent. See also Axiomatic system Dogma First principle, axiom in science and philosophy List of axioms Model theory Regulæ Juris Theorem Presupposition Physical law Principle Notes References Further reading Mendelson, Elliot (1987). Introduction to mathematical logic. Belmont, California: Wadsworth & Brooks. External links Metamath axioms page Ancient Greek philosophy Concepts in ancient Greek metaphysics Concepts in epistemology Concepts in ethics Concepts in logic Concepts in metaphysics Concepts in the philosophy of science Deductive reasoning Formal systems History of logic History of mathematics History of philosophy History of science Intellectual history Logic Mathematical logic Mathematical terminology Philosophical terminology Reasoning

The completeness theorem and the incompleteness theorem, despite their names, do not contradict one another. Further discussion Early mathematicians regarded axiomatic geometry as a model of physical space, and obviously, there could only be one such model. The idea that alternative mathematical systems might exist was very troubling to mathematicians of the 19th century and the developers of systems such as Boolean algebra made elaborate efforts to derive them from traditional arithmetic. Galois showed just before his untimely death that these efforts were largely wasted. Ultimately, the abstract parallels between algebraic systems were seen to be more important than the details, and modern algebra was born. In the modern view, axioms may be any set of formulas, as long as they are not known to be inconsistent. See also Axiomatic system Dogma First principle, axiom in science and philosophy List of axioms Model theory Regulæ Juris Theorem Presupposition Physical law Principle Notes References Further reading Mendelson, Elliot (1987). Introduction to mathematical logic. Belmont, California: Wadsworth & Brooks. External links Metamath axioms page Ancient Greek philosophy Concepts in ancient Greek metaphysics Concepts in epistemology Concepts in ethics Concepts in logic Concepts in metaphysics Concepts in the philosophy of science Deductive reasoning Formal systems History of logic History of mathematics History of philosophy History of science Intellectual history Logic Mathematical logic Mathematical terminology Philosophical terminology Reasoning

The completeness theorem and the incompleteness theorem, despite their names, do not contradict one another. Further discussion Early mathematicians regarded axiomatic geometry as a model of physical space, and obviously, there could only be one such model. The idea that alternative mathematical systems might exist was very troubling to mathematicians of the 19th century and the developers of systems such as Boolean algebra made elaborate efforts to derive them from traditional arithmetic. Galois showed just before his untimely death that these efforts were largely wasted. Ultimately, the abstract parallels between algebraic systems were seen to be more important than the details, and modern algebra was born. In the modern view, axioms may be any set of formulas, as long as they are not known to be inconsistent. See also Axiomatic system Dogma First principle, axiom in science and philosophy List of axioms Model theory Regulæ Juris Theorem Presupposition Physical law Principle Notes References Further reading Mendelson, Elliot (1987). Introduction to mathematical logic. Belmont, California: Wadsworth & Brooks. External links Metamath axioms page Ancient Greek philosophy Concepts in ancient Greek metaphysics Concepts in epistemology Concepts in ethics Concepts in logic Concepts in metaphysics Concepts in the philosophy of science Deductive reasoning Formal systems History of logic History of mathematics History of philosophy History of science Intellectual history Logic Mathematical logic Mathematical terminology Philosophical terminology Reasoning

Alpha Alpha (uppercase , lowercase ; , álpha, or ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , which is the West Semitic word for "ox". Letters that arose from alpha include the Latin letter A and the Cyrillic letter А. Uses Greek In Ancient Greek, alpha was pronounced and could be either phonemically long ([aː]) or short ([a]). Where there is ambiguity, long and short alpha are sometimes written with a macron and breve today: Ᾱᾱ, Ᾰᾰ. ὥρα = ὥρᾱ hōrā "a time" γλῶσσα = γλῶσσᾰ glôssa "tongue" In Modern Greek, vowel length has been lost, and all instances of alpha simply represent . In the polytonic orthography of Greek, alpha, like other vowel letters, can occur with several diacritic marks: any of three accent symbols (), and either of two breathing marks (), as well as combinations of these. It can also combine with the iota subscript (). Greek grammar In the Attic–Ionic dialect of Ancient Greek, long alpha fronted to (eta). In Ionic, the shift took place in all positions. In Attic, the shift did not take place after epsilon, iota, and rho (ε, ι, ρ; e, i, r). In Doric and Aeolic, long alpha is preserved in all positions. Doric, Aeolic, Attic chṓrā – Ionic chṓrē, "country" Doric, Aeolic phā́mā – Attic, Ionic phḗmē, "report" Privative a is the Ancient Greek prefix ἀ- or ἀν- a-, an-, added to words to negate them. It originates from the Proto-Indo-European * (syllabic nasal) and is cognate with English un-. Copulative a is the Greek prefix ἁ- or ἀ- ha-, a-. It comes from Proto-Indo-European *. Mathematics and science The letter alpha represents various concepts in physics and chemistry, including alpha radiation, angular acceleration, alpha particles, alpha carbon and strength of electromagnetic interaction (as Fine-structure constant). Alpha also stands for thermal expansion coefficient of a compound in physical chemistry. It is also commonly used in mathematics in algebraic solutions representing quantities such as angles. Furthermore, in mathematics, the letter alpha is used to denote the area underneath a normal curve in statistics to denote significance level when proving null and alternative hypotheses. In ethology, it is used to name the dominant individual in a group of animals. In aerodynamics, the letter is used as a symbol for the angle of attack of an aircraft and the word "alpha" is used as a synonym for this property. In mathematical logic, α is sometimes used as a placeholder for ordinal numbers. The proportionality operator "∝" (in Unicode: U+221D) is sometimes mistaken for alpha. The uppercase letter alpha is not generally used as a symbol because it tends to be rendered identically to the uppercase Latin A. International Phonetic Alphabet In the International Phonetic Alphabet, the letter ɑ, which looks similar to the lower-case alpha, represents the open back unrounded vowel.

Alpha Alpha (uppercase , lowercase ; , álpha, or ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , which is the West Semitic word for "ox". Letters that arose from alpha include the Latin letter A and the Cyrillic letter А. Uses Greek In Ancient Greek, alpha was pronounced and could be either phonemically long ([aː]) or short ([a]). Where there is ambiguity, long and short alpha are sometimes written with a macron and breve today: Ᾱᾱ, Ᾰᾰ. ὥρα = ὥρᾱ hōrā "a time" γλῶσσα = γλῶσσᾰ glôssa "tongue" In Modern Greek, vowel length has been lost, and all instances of alpha simply represent . In the polytonic orthography of Greek, alpha, like other vowel letters, can occur with several diacritic marks: any of three accent symbols (), and either of two breathing marks (), as well as combinations of these. It can also combine with the iota subscript (). Greek grammar In the Attic–Ionic dialect of Ancient Greek, long alpha fronted to (eta). In Ionic, the shift took place in all positions. In Attic, the shift did not take place after epsilon, iota, and rho (ε, ι, ρ; e, i, r). In Doric and Aeolic, long alpha is preserved in all positions. Doric, Aeolic, Attic chṓrā – Ionic chṓrē, "country" Doric, Aeolic phā́mā – Attic, Ionic phḗmē, "report" Privative a is the Ancient Greek prefix ἀ- or ἀν- a-, an-, added to words to negate them. It originates from the Proto-Indo-European * (syllabic nasal) and is cognate with English un-. Copulative a is the Greek prefix ἁ- or ἀ- ha-, a-. It comes from Proto-Indo-European *. Mathematics and science The letter alpha represents various concepts in physics and chemistry, including alpha radiation, angular acceleration, alpha particles, alpha carbon and strength of electromagnetic interaction (as Fine-structure constant). Alpha also stands for thermal expansion coefficient of a compound in physical chemistry. It is also commonly used in mathematics in algebraic solutions representing quantities such as angles. Furthermore, in mathematics, the letter alpha is used to denote the area underneath a normal curve in statistics to denote significance level when proving null and alternative hypotheses. In ethology, it is used to name the dominant individual in a group of animals. In aerodynamics, the letter is used as a symbol for the angle of attack of an aircraft and the word "alpha" is used as a synonym for this property. In mathematical logic, α is sometimes used as a placeholder for ordinal numbers. The proportionality operator "∝" (in Unicode: U+221D) is sometimes mistaken for alpha. The uppercase letter alpha is not generally used as a symbol because it tends to be rendered identically to the uppercase Latin A. International Phonetic Alphabet In the International Phonetic Alphabet, the letter ɑ, which looks similar to the lower-case alpha, represents the open back unrounded vowel.

History and symbolism Origin The Phoenician alphabet was adopted for Greek in the early 8th century BC, perhaps in Euboea. The majority of the letters of the Phoenician alphabet were adopted into Greek with much the same sounds as they had had in Phoenician, but ʼāleph, the Phoenician letter representing the glottal stop , was adopted as representing the vowel ; similarly, hē and ʽayin are Phoenician consonants that became Greek vowels, epsilon and omicron , respectively. Plutarch Plutarch, in Moralia, presents a discussion on why the letter alpha stands first in the alphabet. Ammonius asks Plutarch what he, being a Boeotian, has to say for Cadmus, the Phoenician who reputedly settled in Thebes and introduced the alphabet to Greece, placing alpha first because it is the Phoenician name for ox—which, unlike Hesiod, the Phoenicians considered not the second or third, but the first of all necessities. "Nothing at all," Plutarch replied. He then added that he would rather be assisted by Lamprias, his own grandfather, than by Dionysus' grandfather, i.e. Cadmus. For Lamprias had said that the first articulate sound made is "alpha", because it is very plain and simple—the air coming off the mouth does not require any motion of the tongue—and therefore this is the first sound that children make. According to Plutarch's natural order of attribution of the vowels to the planets, alpha was connected with the Moon. Alpha and Omega As the first letter of the alphabet, Alpha as a Greek numeral came to represent the number 1. Therefore, Alpha, both as a symbol and term, is used to refer to the "first", or "primary", or "principal" (most significant) occurrence or status of a thing. The New Testament has God declaring himself to be the "Alpha and Omega, the beginning and the end, the first and the last." (Revelation 22:13, KJV, and see also 1:8). Consequently, the term "alpha" has also come to be used to denote "primary" position in social hierarchy, examples being "alpha males" or pack leaders. Computer encodings Greek alpha / Coptic alfa For accented Greek characters, see Greek diacritics: Computer encoding. Latin / IPA alpha Mathematical / Technical alpha References Greek letters Vowel letters

History and symbolism Origin The Phoenician alphabet was adopted for Greek in the early 8th century BC, perhaps in Euboea. The majority of the letters of the Phoenician alphabet were adopted into Greek with much the same sounds as they had had in Phoenician, but ʼāleph, the Phoenician letter representing the glottal stop , was adopted as representing the vowel ; similarly, hē and ʽayin are Phoenician consonants that became Greek vowels, epsilon and omicron , respectively. Plutarch Plutarch, in Moralia, presents a discussion on why the letter alpha stands first in the alphabet. Ammonius asks Plutarch what he, being a Boeotian, has to say for Cadmus, the Phoenician who reputedly settled in Thebes and introduced the alphabet to Greece, placing alpha first because it is the Phoenician name for ox—which, unlike Hesiod, the Phoenicians considered not the second or third, but the first of all necessities. "Nothing at all," Plutarch replied. He then added that he would rather be assisted by Lamprias, his own grandfather, than by Dionysus' grandfather, i.e. Cadmus. For Lamprias had said that the first articulate sound made is "alpha", because it is very plain and simple—the air coming off the mouth does not require any motion of the tongue—and therefore this is the first sound that children make. According to Plutarch's natural order of attribution of the vowels to the planets, alpha was connected with the Moon. Alpha and Omega As the first letter of the alphabet, Alpha as a Greek numeral came to represent the number 1. Therefore, Alpha, both as a symbol and term, is used to refer to the "first", or "primary", or "principal" (most significant) occurrence or status of a thing. The New Testament has God declaring himself to be the "Alpha and Omega, the beginning and the end, the first and the last." (Revelation 22:13, KJV, and see also 1:8). Consequently, the term "alpha" has also come to be used to denote "primary" position in social hierarchy, examples being "alpha males" or pack leaders. Computer encodings Greek alpha / Coptic alfa For accented Greek characters, see Greek diacritics: Computer encoding. Latin / IPA alpha Mathematical / Technical alpha References Greek letters Vowel letters

History and symbolism Origin The Phoenician alphabet was adopted for Greek in the early 8th century BC, perhaps in Euboea. The majority of the letters of the Phoenician alphabet were adopted into Greek with much the same sounds as they had had in Phoenician, but ʼāleph, the Phoenician letter representing the glottal stop , was adopted as representing the vowel ; similarly, hē and ʽayin are Phoenician consonants that became Greek vowels, epsilon and omicron , respectively. Plutarch Plutarch, in Moralia, presents a discussion on why the letter alpha stands first in the alphabet. Ammonius asks Plutarch what he, being a Boeotian, has to say for Cadmus, the Phoenician who reputedly settled in Thebes and introduced the alphabet to Greece, placing alpha first because it is the Phoenician name for ox—which, unlike Hesiod, the Phoenicians considered not the second or third, but the first of all necessities. "Nothing at all," Plutarch replied. He then added that he would rather be assisted by Lamprias, his own grandfather, than by Dionysus' grandfather, i.e. Cadmus. For Lamprias had said that the first articulate sound made is "alpha", because it is very plain and simple—the air coming off the mouth does not require any motion of the tongue—and therefore this is the first sound that children make. According to Plutarch's natural order of attribution of the vowels to the planets, alpha was connected with the Moon. Alpha and Omega As the first letter of the alphabet, Alpha as a Greek numeral came to represent the number 1. Therefore, Alpha, both as a symbol and term, is used to refer to the "first", or "primary", or "principal" (most significant) occurrence or status of a thing. The New Testament has God declaring himself to be the "Alpha and Omega, the beginning and the end, the first and the last." (Revelation 22:13, KJV, and see also 1:8). Consequently, the term "alpha" has also come to be used to denote "primary" position in social hierarchy, examples being "alpha males" or pack leaders. Computer encodings Greek alpha / Coptic alfa For accented Greek characters, see Greek diacritics: Computer encoding. Latin / IPA alpha Mathematical / Technical alpha References Greek letters Vowel letters

Alvin Toffler Alvin Toffler (October 4, 1928 – June 27, 2016) was an American writer, futurist, and businessman known for his works discussing modern technologies, including the digital revolution and the communication revolution, with emphasis on their effects on cultures worldwide. He is regarded as one of the world's outstanding futurists. Toffler was an associate editor of Fortune magazine. In his early works he focused on technology and its impact, which he termed "information overload." In 1970, his first major book about the future, Future Shock, became a worldwide best-seller and has sold over 6 million copies. He and his wife Heidi Toffler, who collaborated with him for most of his writings, moved on to examining the reaction to changes in society with another best-selling book, The Third Wave in 1980. In it, he foresaw such technological advances as cloning, personal computers, the Internet, cable television and mobile communication. His later focus, via their other best-seller, Powershift, (1990), was on the increasing power of 21st-century military hardware and the proliferation of new technologies. He founded Toffler Associates, a management consulting company, and was a visiting scholar at the Russell Sage Foundation, visiting professor at Cornell University, faculty member of the New School for Social Research, a White House correspondent, and a business consultant. Toffler's ideas and writings were a significant influence on the thinking of business and government leaders worldwide, including China's Zhao Ziyang, and AOL founder Steve Case. Early life Alvin Toffler was born on October 4, 1928, in New York City, and raised in Brooklyn. He was the son of Rose (Albaum) and Sam Toffler, a furrier, both Jewish immigrants from Poland. He had one younger sister. He was inspired to become a writer at the age of 7 by his aunt and uncle, who lived with the Tofflers. "They were Depression-era literary intellectuals," Toffler said, "and they always talked about exciting ideas." Toffler graduated from New York University in 1950 as an English major, though by his own account he was more focused on political activism than grades. He met his future wife, Adelaide Elizabeth Farrell (nicknamed "Heidi"), when she was starting a graduate course in linguistics. Being radical students, they decided against further graduate work and moved to the Midwest, where they married on April 29, 1950. Career Seeking experiences to write about, Alvin and Heidi Toffler spent the next five years as blue collar workers on assembly lines while studying industrial mass production in their daily work. He compared his own desire for experience to other writers, such as Jack London, who in his quest for subjects to write about sailed the seas, and John Steinbeck, who went to pick grapes with migrant workers. In their first factory jobs, Heidi became a union shop steward in the aluminum foundry where she worked. Alvin became a millwright and welder. In the evenings Alvin would write poetry and fiction, but discovered he was proficient at neither.

Alvin Toffler Alvin Toffler (October 4, 1928 – June 27, 2016) was an American writer, futurist, and businessman known for his works discussing modern technologies, including the digital revolution and the communication revolution, with emphasis on their effects on cultures worldwide. He is regarded as one of the world's outstanding futurists. Toffler was an associate editor of Fortune magazine. In his early works he focused on technology and its impact, which he termed "information overload." In 1970, his first major book about the future, Future Shock, became a worldwide best-seller and has sold over 6 million copies. He and his wife Heidi Toffler, who collaborated with him for most of his writings, moved on to examining the reaction to changes in society with another best-selling book, The Third Wave in 1980. In it, he foresaw such technological advances as cloning, personal computers, the Internet, cable television and mobile communication. His later focus, via their other best-seller, Powershift, (1990), was on the increasing power of 21st-century military hardware and the proliferation of new technologies. He founded Toffler Associates, a management consulting company, and was a visiting scholar at the Russell Sage Foundation, visiting professor at Cornell University, faculty member of the New School for Social Research, a White House correspondent, and a business consultant. Toffler's ideas and writings were a significant influence on the thinking of business and government leaders worldwide, including China's Zhao Ziyang, and AOL founder Steve Case. Early life Alvin Toffler was born on October 4, 1928, in New York City, and raised in Brooklyn. He was the son of Rose (Albaum) and Sam Toffler, a furrier, both Jewish immigrants from Poland. He had one younger sister. He was inspired to become a writer at the age of 7 by his aunt and uncle, who lived with the Tofflers. "They were Depression-era literary intellectuals," Toffler said, "and they always talked about exciting ideas." Toffler graduated from New York University in 1950 as an English major, though by his own account he was more focused on political activism than grades. He met his future wife, Adelaide Elizabeth Farrell (nicknamed "Heidi"), when she was starting a graduate course in linguistics. Being radical students, they decided against further graduate work and moved to the Midwest, where they married on April 29, 1950. Career Seeking experiences to write about, Alvin and Heidi Toffler spent the next five years as blue collar workers on assembly lines while studying industrial mass production in their daily work. He compared his own desire for experience to other writers, such as Jack London, who in his quest for subjects to write about sailed the seas, and John Steinbeck, who went to pick grapes with migrant workers. In their first factory jobs, Heidi became a union shop steward in the aluminum foundry where she worked. Alvin became a millwright and welder. In the evenings Alvin would write poetry and fiction, but discovered he was proficient at neither.

His hands-on practical labor experience helped Alvin Toffler land a position at a union-backed newspaper, a transfer to its Washington bureau in 1957, then three years as a White House correspondent, covering Congress and the White House for a Pennsylvania daily newspaper. They returned to New York City in 1959 when Fortune magazine invited Alvin to become its labor columnist, later having him write about business and management. After leaving Fortune magazine in 1962, Toffler began a freelance career, writing long form articles for scholarly journals and magazines. His 1964 Playboy interviews with Russian novelist Vladimir Nabokov and Ayn Rand were considered among the magazine's best. His interview with Rand was the first time the magazine had given such a platform to a female intellectual, which as one commentator said, "the real bird of paradise Toffler captured for Playboy in 1964 was Ayn Rand." Toffler was hired by IBM to conduct research and write a paper on the social and organizational impact of computers, leading to his contact with the earliest computer "gurus" and artificial intelligence researchers and proponents. Xerox invited him to write about its research laboratory and AT&T consulted him for strategic advice. This AT&T work led to a study of telecommunications, which advised the company's top management to break up the company more than a decade before the government forced AT&T to break up. In the mid-1960s, the Tofflers began five years of research on what would become Future Shock, published in 1970. It has sold over 6 million copies worldwide, according to the New York Times, or over 15 million copies according to the Tofflers' Web site. Toffler coined the term "future shock" to refer to what happens to a society when change happens too fast, which results in social confusion and normal decision-making processes breaking down. The book has never been out of print and has been translated into dozens of languages. He continued the theme in The Third Wave in 1980. While he describes the first and second waves as the agricultural and industrial revolutions, the "third wave," a phrase he coined, represents the current information, computer-based revolution. He forecast the spread of the Internet and email, interactive media, cable television, cloning, and other digital advancements. He claimed that one of the side effects of the digital age has been "information overload," another term he coined. In 1990, he wrote Powershift, also with the help of his wife, Heidi. In 1996, with American business consultant Tom Johnson, they co-founded Toffler Associates, an advisory firm designed to implement many of the ideas the Tofflers had written on. The firm worked with businesses, NGOs, and governments in the United States, South Korea, Mexico, Brazil, Singapore, Australia, and other countries. During this period in his career, Toffler lectured worldwide, taught at several schools and met world leaders, such as Mikhail Gorbachev, along with key executives and military officials. Ideas and opinions Toffler stated many of his ideas during an interview with the Australian Broadcasting Corporation in 1998.

His hands-on practical labor experience helped Alvin Toffler land a position at a union-backed newspaper, a transfer to its Washington bureau in 1957, then three years as a White House correspondent, covering Congress and the White House for a Pennsylvania daily newspaper. They returned to New York City in 1959 when Fortune magazine invited Alvin to become its labor columnist, later having him write about business and management. After leaving Fortune magazine in 1962, Toffler began a freelance career, writing long form articles for scholarly journals and magazines. His 1964 Playboy interviews with Russian novelist Vladimir Nabokov and Ayn Rand were considered among the magazine's best. His interview with Rand was the first time the magazine had given such a platform to a female intellectual, which as one commentator said, "the real bird of paradise Toffler captured for Playboy in 1964 was Ayn Rand." Toffler was hired by IBM to conduct research and write a paper on the social and organizational impact of computers, leading to his contact with the earliest computer "gurus" and artificial intelligence researchers and proponents. Xerox invited him to write about its research laboratory and AT&T consulted him for strategic advice. This AT&T work led to a study of telecommunications, which advised the company's top management to break up the company more than a decade before the government forced AT&T to break up. In the mid-1960s, the Tofflers began five years of research on what would become Future Shock, published in 1970. It has sold over 6 million copies worldwide, according to the New York Times, or over 15 million copies according to the Tofflers' Web site. Toffler coined the term "future shock" to refer to what happens to a society when change happens too fast, which results in social confusion and normal decision-making processes breaking down. The book has never been out of print and has been translated into dozens of languages. He continued the theme in The Third Wave in 1980. While he describes the first and second waves as the agricultural and industrial revolutions, the "third wave," a phrase he coined, represents the current information, computer-based revolution. He forecast the spread of the Internet and email, interactive media, cable television, cloning, and other digital advancements. He claimed that one of the side effects of the digital age has been "information overload," another term he coined. In 1990, he wrote Powershift, also with the help of his wife, Heidi. In 1996, with American business consultant Tom Johnson, they co-founded Toffler Associates, an advisory firm designed to implement many of the ideas the Tofflers had written on. The firm worked with businesses, NGOs, and governments in the United States, South Korea, Mexico, Brazil, Singapore, Australia, and other countries. During this period in his career, Toffler lectured worldwide, taught at several schools and met world leaders, such as Mikhail Gorbachev, along with key executives and military officials. Ideas and opinions Toffler stated many of his ideas during an interview with the Australian Broadcasting Corporation in 1998.

His hands-on practical labor experience helped Alvin Toffler land a position at a union-backed newspaper, a transfer to its Washington bureau in 1957, then three years as a White House correspondent, covering Congress and the White House for a Pennsylvania daily newspaper. They returned to New York City in 1959 when Fortune magazine invited Alvin to become its labor columnist, later having him write about business and management. After leaving Fortune magazine in 1962, Toffler began a freelance career, writing long form articles for scholarly journals and magazines. His 1964 Playboy interviews with Russian novelist Vladimir Nabokov and Ayn Rand were considered among the magazine's best. His interview with Rand was the first time the magazine had given such a platform to a female intellectual, which as one commentator said, "the real bird of paradise Toffler captured for Playboy in 1964 was Ayn Rand." Toffler was hired by IBM to conduct research and write a paper on the social and organizational impact of computers, leading to his contact with the earliest computer "gurus" and artificial intelligence researchers and proponents. Xerox invited him to write about its research laboratory and AT&T consulted him for strategic advice. This AT&T work led to a study of telecommunications, which advised the company's top management to break up the company more than a decade before the government forced AT&T to break up. In the mid-1960s, the Tofflers began five years of research on what would become Future Shock, published in 1970. It has sold over 6 million copies worldwide, according to the New York Times, or over 15 million copies according to the Tofflers' Web site. Toffler coined the term "future shock" to refer to what happens to a society when change happens too fast, which results in social confusion and normal decision-making processes breaking down. The book has never been out of print and has been translated into dozens of languages. He continued the theme in The Third Wave in 1980. While he describes the first and second waves as the agricultural and industrial revolutions, the "third wave," a phrase he coined, represents the current information, computer-based revolution. He forecast the spread of the Internet and email, interactive media, cable television, cloning, and other digital advancements. He claimed that one of the side effects of the digital age has been "information overload," another term he coined. In 1990, he wrote Powershift, also with the help of his wife, Heidi. In 1996, with American business consultant Tom Johnson, they co-founded Toffler Associates, an advisory firm designed to implement many of the ideas the Tofflers had written on. The firm worked with businesses, NGOs, and governments in the United States, South Korea, Mexico, Brazil, Singapore, Australia, and other countries. During this period in his career, Toffler lectured worldwide, taught at several schools and met world leaders, such as Mikhail Gorbachev, along with key executives and military officials. Ideas and opinions Toffler stated many of his ideas during an interview with the Australian Broadcasting Corporation in 1998.

"Society needs people who take care of the elderly and who know how to be compassionate and honest," he said. "Society needs people who work in hospitals. Society needs all kinds of skills that are not just cognitive; they're emotional, they're affectional. You can't run the society on data and computers alone." His opinions about the future of education, many of which were in Future Shock, have often been quoted. An often misattributed quote, however, is that of psychologist Herbert Gerjuoy: "Tomorrow's illiterate will not be the man who can't read; he will be the man who has not learned how to learn." Early in his career, after traveling to other countries, he became aware of the new and myriad inputs that visitors received from these other cultures. He explained during an interview that some visitors would become "truly disoriented and upset" by the strange environment, which he described as a reaction to culture shock. From that issue, he foresaw another problem for the future, when a culturally "new environment comes to you ... and comes to you rapidly." That kind of sudden cultural change within one's own country, which he felt many would not understand, would lead to a similar reaction, one of "future shock", which he wrote about in his book by that title. Toffler writes: In The Third Wave, Toffler describes three types of societies, based on the concept of "waves"—each wave pushes the older societies and cultures aside. He describes the "First Wave" as the society after agrarian revolution and replaced the first hunter-gatherer cultures. The "Second Wave," he labels society during the Industrial Revolution (ca. late 17th century through the mid-20th century). That period saw the increase of urban industrial populations which had undermined the traditional nuclear family, and initiated a factory-like education system, and the growth of the corporation. Toffler said: The "Third Wave" was a term he coined to describe the post-industrial society, which began in the late 1950s. His description of this period dovetails with other futurist writers, who also wrote about the Information Age, Space Age, Electronic Era, Global Village, terms which highlighted a scientific-technological revolution. The Tofflers claimed to have predicted a number of geopolitical events, such as the collapse of the Soviet Union, the fall of the Berlin Wall and the future economic growth in the Asia-Pacific region. Influences and popular culture Toffler often visited with dignitaries in Asia, including China's Zhao Ziyang, Singapore's Lee Kuan Yew and South Korea's Kim Dae Jung, all of whom were influenced by his views as Asia's emerging markets increased in global significance during the 1980s and 1990s. Although they had originally censored some of his books and ideas, China's government cited him along with Franklin Roosevelt and Bill Gates as being among the Westerners who had most influenced their country. The Third Wave along with a video documentary based on it became best-sellers in China and were widely distributed to schools.

"Society needs people who take care of the elderly and who know how to be compassionate and honest," he said. "Society needs people who work in hospitals. Society needs all kinds of skills that are not just cognitive; they're emotional, they're affectional. You can't run the society on data and computers alone." His opinions about the future of education, many of which were in Future Shock, have often been quoted. An often misattributed quote, however, is that of psychologist Herbert Gerjuoy: "Tomorrow's illiterate will not be the man who can't read; he will be the man who has not learned how to learn." Early in his career, after traveling to other countries, he became aware of the new and myriad inputs that visitors received from these other cultures. He explained during an interview that some visitors would become "truly disoriented and upset" by the strange environment, which he described as a reaction to culture shock. From that issue, he foresaw another problem for the future, when a culturally "new environment comes to you ... and comes to you rapidly." That kind of sudden cultural change within one's own country, which he felt many would not understand, would lead to a similar reaction, one of "future shock", which he wrote about in his book by that title. Toffler writes: In The Third Wave, Toffler describes three types of societies, based on the concept of "waves"—each wave pushes the older societies and cultures aside. He describes the "First Wave" as the society after agrarian revolution and replaced the first hunter-gatherer cultures. The "Second Wave," he labels society during the Industrial Revolution (ca. late 17th century through the mid-20th century). That period saw the increase of urban industrial populations which had undermined the traditional nuclear family, and initiated a factory-like education system, and the growth of the corporation. Toffler said: The "Third Wave" was a term he coined to describe the post-industrial society, which began in the late 1950s. His description of this period dovetails with other futurist writers, who also wrote about the Information Age, Space Age, Electronic Era, Global Village, terms which highlighted a scientific-technological revolution. The Tofflers claimed to have predicted a number of geopolitical events, such as the collapse of the Soviet Union, the fall of the Berlin Wall and the future economic growth in the Asia-Pacific region. Influences and popular culture Toffler often visited with dignitaries in Asia, including China's Zhao Ziyang, Singapore's Lee Kuan Yew and South Korea's Kim Dae Jung, all of whom were influenced by his views as Asia's emerging markets increased in global significance during the 1980s and 1990s. Although they had originally censored some of his books and ideas, China's government cited him along with Franklin Roosevelt and Bill Gates as being among the Westerners who had most influenced their country. The Third Wave along with a video documentary based on it became best-sellers in China and were widely distributed to schools.

"Society needs people who take care of the elderly and who know how to be compassionate and honest," he said. "Society needs people who work in hospitals. Society needs all kinds of skills that are not just cognitive; they're emotional, they're affectional. You can't run the society on data and computers alone." His opinions about the future of education, many of which were in Future Shock, have often been quoted. An often misattributed quote, however, is that of psychologist Herbert Gerjuoy: "Tomorrow's illiterate will not be the man who can't read; he will be the man who has not learned how to learn." Early in his career, after traveling to other countries, he became aware of the new and myriad inputs that visitors received from these other cultures. He explained during an interview that some visitors would become "truly disoriented and upset" by the strange environment, which he described as a reaction to culture shock. From that issue, he foresaw another problem for the future, when a culturally "new environment comes to you ... and comes to you rapidly." That kind of sudden cultural change within one's own country, which he felt many would not understand, would lead to a similar reaction, one of "future shock", which he wrote about in his book by that title. Toffler writes: In The Third Wave, Toffler describes three types of societies, based on the concept of "waves"—each wave pushes the older societies and cultures aside. He describes the "First Wave" as the society after agrarian revolution and replaced the first hunter-gatherer cultures. The "Second Wave," he labels society during the Industrial Revolution (ca. late 17th century through the mid-20th century). That period saw the increase of urban industrial populations which had undermined the traditional nuclear family, and initiated a factory-like education system, and the growth of the corporation. Toffler said: The "Third Wave" was a term he coined to describe the post-industrial society, which began in the late 1950s. His description of this period dovetails with other futurist writers, who also wrote about the Information Age, Space Age, Electronic Era, Global Village, terms which highlighted a scientific-technological revolution. The Tofflers claimed to have predicted a number of geopolitical events, such as the collapse of the Soviet Union, the fall of the Berlin Wall and the future economic growth in the Asia-Pacific region. Influences and popular culture Toffler often visited with dignitaries in Asia, including China's Zhao Ziyang, Singapore's Lee Kuan Yew and South Korea's Kim Dae Jung, all of whom were influenced by his views as Asia's emerging markets increased in global significance during the 1980s and 1990s. Although they had originally censored some of his books and ideas, China's government cited him along with Franklin Roosevelt and Bill Gates as being among the Westerners who had most influenced their country. The Third Wave along with a video documentary based on it became best-sellers in China and were widely distributed to schools.

The video's success inspired the marketing of videos on related themes in the late 1990s by Infowars, whose name is derived from the term coined by Toffler in the book. Toffler's influence on Asian thinkers was summed up in an article in Daedalus, published by the American Academy of Arts & Sciences: U.S. House Speaker Newt Gingrich publicly lauded his ideas about the future, and urged members of Congress to read Toffler's book, Creating a New Civilization (1995). Others, such as AOL founder Steve Case, cited Toffler's The Third Wave as a formative influence on his thinking, which inspired him to write The Third Wave: An Entrepreneur's Vision of the Future in 2016. Case said that Toffler was a "real pioneer in helping people, companies and even countries lean into the future." In 1980, Ted Turner founded CNN, which he said was inspired by Toffler's forecasting the end of the dominance of the three main television networks. Turner's company, Turner Broadcasting, published Toffler's Creating a New Civilization in 1995. Shortly after the book was released, the former Soviet president Mikhail Gorbachev hosted the Global Governance Conference in San Francisco with the theme, Toward a New Civilization, which was attended by dozens of world figures, including the Tofflers, George H. W. Bush, Margaret Thatcher, Carl Sagan, Abba Eban and Turner with his then-wife, actress Jane Fonda. Mexican billionaire Carlos Slim was influenced by his works, and became a friend of the writer. Global marketer J.D. Power also said he was inspired by Toffler's works. Since the 1960s, people had tried to make sense out of the effect of new technologies and social change, a problem which made Toffler's writings widely influential beyond the confines of scientific, economic, and public policy. His works and ideas have been subject to various criticisms, usually with the same argumentation used against futurology: that foreseeing the future is nigh impossible. Techno music pioneer Juan Atkins cites Toffler's phrase "techno rebels" in The Third Wave as inspiring him to use the word "techno" to describe the musical style he helped to create Musician Curtis Mayfield released a disco song called "Future Shock," later covered in an electro version by Herbie Hancock. Science fiction author John Brunner wrote "The Shockwave Rider," from the concept of "future shock." The nightclub Toffler, in Rotterdam, is named after him. In the song "Victoria" by The Exponents, the protagonist's daily routine and cultural interests are described: "She's up in time to watch the soap operas, reads Cosmopolitan and Alvin Toffler". Critical assessment Accenture, the management consultancy firm, identified Toffler in 2002 as being among the most influential voices in business leaders, along with Bill Gates and Peter Drucker. Toffler has also been described in a Financial Times interview as the "world's most famous futurologist". In 2006, the People's Daily classed him among the 50 foreigners who shaped modern China, which one U.S. newspaper notes made him a "guru of sorts to world statesmen."

The video's success inspired the marketing of videos on related themes in the late 1990s by Infowars, whose name is derived from the term coined by Toffler in the book. Toffler's influence on Asian thinkers was summed up in an article in Daedalus, published by the American Academy of Arts & Sciences: U.S. House Speaker Newt Gingrich publicly lauded his ideas about the future, and urged members of Congress to read Toffler's book, Creating a New Civilization (1995). Others, such as AOL founder Steve Case, cited Toffler's The Third Wave as a formative influence on his thinking, which inspired him to write The Third Wave: An Entrepreneur's Vision of the Future in 2016. Case said that Toffler was a "real pioneer in helping people, companies and even countries lean into the future." In 1980, Ted Turner founded CNN, which he said was inspired by Toffler's forecasting the end of the dominance of the three main television networks. Turner's company, Turner Broadcasting, published Toffler's Creating a New Civilization in 1995. Shortly after the book was released, the former Soviet president Mikhail Gorbachev hosted the Global Governance Conference in San Francisco with the theme, Toward a New Civilization, which was attended by dozens of world figures, including the Tofflers, George H. W. Bush, Margaret Thatcher, Carl Sagan, Abba Eban and Turner with his then-wife, actress Jane Fonda. Mexican billionaire Carlos Slim was influenced by his works, and became a friend of the writer. Global marketer J.D. Power also said he was inspired by Toffler's works. Since the 1960s, people had tried to make sense out of the effect of new technologies and social change, a problem which made Toffler's writings widely influential beyond the confines of scientific, economic, and public policy. His works and ideas have been subject to various criticisms, usually with the same argumentation used against futurology: that foreseeing the future is nigh impossible. Techno music pioneer Juan Atkins cites Toffler's phrase "techno rebels" in The Third Wave as inspiring him to use the word "techno" to describe the musical style he helped to create Musician Curtis Mayfield released a disco song called "Future Shock," later covered in an electro version by Herbie Hancock. Science fiction author John Brunner wrote "The Shockwave Rider," from the concept of "future shock." The nightclub Toffler, in Rotterdam, is named after him. In the song "Victoria" by The Exponents, the protagonist's daily routine and cultural interests are described: "She's up in time to watch the soap operas, reads Cosmopolitan and Alvin Toffler". Critical assessment Accenture, the management consultancy firm, identified Toffler in 2002 as being among the most influential voices in business leaders, along with Bill Gates and Peter Drucker. Toffler has also been described in a Financial Times interview as the "world's most famous futurologist". In 2006, the People's Daily classed him among the 50 foreigners who shaped modern China, which one U.S. newspaper notes made him a "guru of sorts to world statesmen."

The video's success inspired the marketing of videos on related themes in the late 1990s by Infowars, whose name is derived from the term coined by Toffler in the book. Toffler's influence on Asian thinkers was summed up in an article in Daedalus, published by the American Academy of Arts & Sciences: U.S. House Speaker Newt Gingrich publicly lauded his ideas about the future, and urged members of Congress to read Toffler's book, Creating a New Civilization (1995). Others, such as AOL founder Steve Case, cited Toffler's The Third Wave as a formative influence on his thinking, which inspired him to write The Third Wave: An Entrepreneur's Vision of the Future in 2016. Case said that Toffler was a "real pioneer in helping people, companies and even countries lean into the future." In 1980, Ted Turner founded CNN, which he said was inspired by Toffler's forecasting the end of the dominance of the three main television networks. Turner's company, Turner Broadcasting, published Toffler's Creating a New Civilization in 1995. Shortly after the book was released, the former Soviet president Mikhail Gorbachev hosted the Global Governance Conference in San Francisco with the theme, Toward a New Civilization, which was attended by dozens of world figures, including the Tofflers, George H. W. Bush, Margaret Thatcher, Carl Sagan, Abba Eban and Turner with his then-wife, actress Jane Fonda. Mexican billionaire Carlos Slim was influenced by his works, and became a friend of the writer. Global marketer J.D. Power also said he was inspired by Toffler's works. Since the 1960s, people had tried to make sense out of the effect of new technologies and social change, a problem which made Toffler's writings widely influential beyond the confines of scientific, economic, and public policy. His works and ideas have been subject to various criticisms, usually with the same argumentation used against futurology: that foreseeing the future is nigh impossible. Techno music pioneer Juan Atkins cites Toffler's phrase "techno rebels" in The Third Wave as inspiring him to use the word "techno" to describe the musical style he helped to create Musician Curtis Mayfield released a disco song called "Future Shock," later covered in an electro version by Herbie Hancock. Science fiction author John Brunner wrote "The Shockwave Rider," from the concept of "future shock." The nightclub Toffler, in Rotterdam, is named after him. In the song "Victoria" by The Exponents, the protagonist's daily routine and cultural interests are described: "She's up in time to watch the soap operas, reads Cosmopolitan and Alvin Toffler". Critical assessment Accenture, the management consultancy firm, identified Toffler in 2002 as being among the most influential voices in business leaders, along with Bill Gates and Peter Drucker. Toffler has also been described in a Financial Times interview as the "world's most famous futurologist". In 2006, the People's Daily classed him among the 50 foreigners who shaped modern China, which one U.S. newspaper notes made him a "guru of sorts to world statesmen."

Chinese Premier and General Secretary Zhao Ziyang was greatly influenced by Toffler. He convened conferences to discuss The Third Wave in the early 1980s, and in 1985 the book was the No. 2 best seller in China. Author Mark Satin characterizes Toffler as an important early influence on radical centrist political thought. Newt Gingrich became close to the Tofflers in the 1970s and said The Third Wave had immensely influenced his own thinking and was "one of the great seminal works of our time." Selected awards Toffler has received several prestigious prizes and awards, including the McKinsey Foundation Book Award for Contributions to Management Literature, Officier de L'Ordre des Arts et Lettres, and appointments, including Fellow of the American Association for the Advancement of Science and the International Institute for Strategic Studies. In 2006, Alvin and Heidi Toffler were recipients of Brown University's Independent Award. Personal life Toffler was married to Heidi Toffler, also a writer and futurist. They lived in the Bel Air section of Los Angeles, California, and previously lived in Redding, Connecticut. The couple's only child, Karen Toffler (1954–2000), died at age 46 after more than a decade suffering from Guillain–Barré syndrome. Alvin Toffler died in his sleep on June 27, 2016, at his home in Los Angeles. No cause of death was given. He is buried at Westwood Memorial Park. Bibliography Alvin Toffler co-wrote his books with his wife Heidi. The Culture Consumers (1964) St. Martin's Press, The Schoolhouse in the City (1968) Praeger (editors), Future Shock (1970) Bantam Books, The Futurists (1972) Random House (editors), Learning for Tomorrow (1974) Random House (editors), The Eco-Spasm Report (1975) Bantam Books, The Third Wave (1980) Bantam Books, Previews & Premises (1983) William Morrow & Co, The Adaptive Corporation (1985) McGraw-Hill, Powershift: Knowledge, Wealth and Violence at the Edge of the 21st Century (1990) Bantam Books, War and Anti-War (1993) Warner Books, Creating a New Civilization (1995) Turner Pub, Revolutionary Wealth (2006) Knopf, See also Daniel Bell Norman Swan Human nature John Naisbitt References External links  – official Alvin Toffler site Toffler Associates Interview with Alvin Toffler by the World Affairs Council Discuss Alvin Toffler's Future Shock with other readers, BookTalk.org Alvin Toffler at Find a Grave Future Shock Forum 2018 Finding aid to the Alvin and Heidi Toffler papers at Columbia University. Rare Book & Manuscript Library 1928 births 2016 deaths American people of Polish-Jewish descent American technology writers American futurologists Burials at Westwood Village Memorial Park Cemetery Jewish American writers People from Ridgefield, Connecticut Writers from Connecticut Writers from Brooklyn 20th-century American non-fiction writers 21st-century American non-fiction writers American transhumanists New York University alumni Singularitarians People from Redding, Connecticut 20th-century American male writers American male non-fiction writers Jewish American journalists People from Bel Air, Los Angeles 21st-century American male writers 21st-century American Jews

Chinese Premier and General Secretary Zhao Ziyang was greatly influenced by Toffler. He convened conferences to discuss The Third Wave in the early 1980s, and in 1985 the book was the No. 2 best seller in China. Author Mark Satin characterizes Toffler as an important early influence on radical centrist political thought. Newt Gingrich became close to the Tofflers in the 1970s and said The Third Wave had immensely influenced his own thinking and was "one of the great seminal works of our time." Selected awards Toffler has received several prestigious prizes and awards, including the McKinsey Foundation Book Award for Contributions to Management Literature, Officier de L'Ordre des Arts et Lettres, and appointments, including Fellow of the American Association for the Advancement of Science and the International Institute for Strategic Studies. In 2006, Alvin and Heidi Toffler were recipients of Brown University's Independent Award. Personal life Toffler was married to Heidi Toffler, also a writer and futurist. They lived in the Bel Air section of Los Angeles, California, and previously lived in Redding, Connecticut. The couple's only child, Karen Toffler (1954–2000), died at age 46 after more than a decade suffering from Guillain–Barré syndrome. Alvin Toffler died in his sleep on June 27, 2016, at his home in Los Angeles. No cause of death was given. He is buried at Westwood Memorial Park. Bibliography Alvin Toffler co-wrote his books with his wife Heidi. The Culture Consumers (1964) St. Martin's Press, The Schoolhouse in the City (1968) Praeger (editors), Future Shock (1970) Bantam Books, The Futurists (1972) Random House (editors), Learning for Tomorrow (1974) Random House (editors), The Eco-Spasm Report (1975) Bantam Books, The Third Wave (1980) Bantam Books, Previews & Premises (1983) William Morrow & Co, The Adaptive Corporation (1985) McGraw-Hill, Powershift: Knowledge, Wealth and Violence at the Edge of the 21st Century (1990) Bantam Books, War and Anti-War (1993) Warner Books, Creating a New Civilization (1995) Turner Pub, Revolutionary Wealth (2006) Knopf, See also Daniel Bell Norman Swan Human nature John Naisbitt References External links  – official Alvin Toffler site Toffler Associates Interview with Alvin Toffler by the World Affairs Council Discuss Alvin Toffler's Future Shock with other readers, BookTalk.org Alvin Toffler at Find a Grave Future Shock Forum 2018 Finding aid to the Alvin and Heidi Toffler papers at Columbia University. Rare Book & Manuscript Library 1928 births 2016 deaths American people of Polish-Jewish descent American technology writers American futurologists Burials at Westwood Village Memorial Park Cemetery Jewish American writers People from Ridgefield, Connecticut Writers from Connecticut Writers from Brooklyn 20th-century American non-fiction writers 21st-century American non-fiction writers American transhumanists New York University alumni Singularitarians People from Redding, Connecticut 20th-century American male writers American male non-fiction writers Jewish American journalists People from Bel Air, Los Angeles 21st-century American male writers 21st-century American Jews

Chinese Premier and General Secretary Zhao Ziyang was greatly influenced by Toffler. He convened conferences to discuss The Third Wave in the early 1980s, and in 1985 the book was the No. 2 best seller in China. Author Mark Satin characterizes Toffler as an important early influence on radical centrist political thought. Newt Gingrich became close to the Tofflers in the 1970s and said The Third Wave had immensely influenced his own thinking and was "one of the great seminal works of our time." Selected awards Toffler has received several prestigious prizes and awards, including the McKinsey Foundation Book Award for Contributions to Management Literature, Officier de L'Ordre des Arts et Lettres, and appointments, including Fellow of the American Association for the Advancement of Science and the International Institute for Strategic Studies. In 2006, Alvin and Heidi Toffler were recipients of Brown University's Independent Award. Personal life Toffler was married to Heidi Toffler, also a writer and futurist. They lived in the Bel Air section of Los Angeles, California, and previously lived in Redding, Connecticut. The couple's only child, Karen Toffler (1954–2000), died at age 46 after more than a decade suffering from Guillain–Barré syndrome. Alvin Toffler died in his sleep on June 27, 2016, at his home in Los Angeles. No cause of death was given. He is buried at Westwood Memorial Park. Bibliography Alvin Toffler co-wrote his books with his wife Heidi. The Culture Consumers (1964) St. Martin's Press, The Schoolhouse in the City (1968) Praeger (editors), Future Shock (1970) Bantam Books, The Futurists (1972) Random House (editors), Learning for Tomorrow (1974) Random House (editors), The Eco-Spasm Report (1975) Bantam Books, The Third Wave (1980) Bantam Books, Previews & Premises (1983) William Morrow & Co, The Adaptive Corporation (1985) McGraw-Hill, Powershift: Knowledge, Wealth and Violence at the Edge of the 21st Century (1990) Bantam Books, War and Anti-War (1993) Warner Books, Creating a New Civilization (1995) Turner Pub, Revolutionary Wealth (2006) Knopf, See also Daniel Bell Norman Swan Human nature John Naisbitt References External links  – official Alvin Toffler site Toffler Associates Interview with Alvin Toffler by the World Affairs Council Discuss Alvin Toffler's Future Shock with other readers, BookTalk.org Alvin Toffler at Find a Grave Future Shock Forum 2018 Finding aid to the Alvin and Heidi Toffler papers at Columbia University. Rare Book & Manuscript Library 1928 births 2016 deaths American people of Polish-Jewish descent American technology writers American futurologists Burials at Westwood Village Memorial Park Cemetery Jewish American writers People from Ridgefield, Connecticut Writers from Connecticut Writers from Brooklyn 20th-century American non-fiction writers 21st-century American non-fiction writers American transhumanists New York University alumni Singularitarians People from Redding, Connecticut 20th-century American male writers American male non-fiction writers Jewish American journalists People from Bel Air, Los Angeles 21st-century American male writers 21st-century American Jews

The Amazing Spider-Man The Amazing Spider-Man is an American comic book series published by Marvel Comics, featuring the fictional superhero Spider-Man as its main protagonist. Being in the mainstream continuity of the franchise, it began publication in 1963 as a bimonthly periodical (as Amazing Fantasy had been), quickly being increased to monthly, and was published continuously, with a brief interruption in 1995, until its second volume with a new numbering order in 1999. In 2003, the series reverted to the numbering order of the first volume. The title has occasionally been published biweekly, and was published three times a month from 2008 to 2010. After DC Comics' relaunch of Action Comics and Detective Comics with new No. 1 issues in 2011, it had been the highest-numbered American comic still in circulation until it was cancelled. The title ended its 50-year run as a continuously published comic with the landmark issue #700 in December 2012. It was replaced by The Superior Spider-Man as part of the Marvel NOW! relaunch of Marvel's comic lines. Volume 3 of The Amazing Spider-Man was published in April 2014, following the conclusion of The Superior Spider-Man story arc. In late 2015, the series was relaunched with a 4th volume, following the 2015 Secret Wars event. The 5th and current volume began in 2018, as part of Marvel's Fresh Start series of comic relaunches. Publication history Writer-editor Stan Lee and artist and co-plotter Steve Ditko created the character of Spider-Man, and the pair produced 38 issues from March 1963 to July 1966. Ditko left after the 38th issue, while Lee remained as writer until issue 100. Since then, many writers and artists have taken over the monthly comic through the years, chronicling the adventures of Marvel's most identifiable hero. The Amazing Spider-Man has been the character's flagship series for his first fifty years in publication, and was the only monthly series to star Spider-Man until Peter Parker, The Spectacular Spider-Man, in 1976, although 1972 saw the debut of Marvel Team-Up, with the vast majority of issues featuring Spider-Man along with a rotating cast of other Marvel characters. Most of the major characters and villains of the Spider-Man saga have been introduced in Amazing, and with few exceptions, it is where most key events in the character's history have occurred. The title was published continuously until No. 441 (Nov. 1998) when Marvel Comics relaunched it as vol. 2 No. 1 (Jan. 1999), but on Spider-Man's 40th anniversary, this new title reverted to using the numbering of the original series, beginning again with issue No. 500 (Dec. 2003) and lasting until the final issue, No. 700 (Feb. 2013). 1960s Due to strong sales on the character's first appearance in Amazing Fantasy No. 15, Spider-Man was given his own ongoing series in March 1963. The initial years of the series, under Lee and Ditko, chronicled Spider-Man's nascent career as a masked super-human vigilante with his civilian life as hard-luck yet perpetually good-humored and well-meaning teenager Peter Parker.

The Amazing Spider-Man The Amazing Spider-Man is an American comic book series published by Marvel Comics, featuring the fictional superhero Spider-Man as its main protagonist. Being in the mainstream continuity of the franchise, it began publication in 1963 as a bimonthly periodical (as Amazing Fantasy had been), quickly being increased to monthly, and was published continuously, with a brief interruption in 1995, until its second volume with a new numbering order in 1999. In 2003, the series reverted to the numbering order of the first volume. The title has occasionally been published biweekly, and was published three times a month from 2008 to 2010. After DC Comics' relaunch of Action Comics and Detective Comics with new No. 1 issues in 2011, it had been the highest-numbered American comic still in circulation until it was cancelled. The title ended its 50-year run as a continuously published comic with the landmark issue #700 in December 2012. It was replaced by The Superior Spider-Man as part of the Marvel NOW! relaunch of Marvel's comic lines. Volume 3 of The Amazing Spider-Man was published in April 2014, following the conclusion of The Superior Spider-Man story arc. In late 2015, the series was relaunched with a 4th volume, following the 2015 Secret Wars event. The 5th and current volume began in 2018, as part of Marvel's Fresh Start series of comic relaunches. Publication history Writer-editor Stan Lee and artist and co-plotter Steve Ditko created the character of Spider-Man, and the pair produced 38 issues from March 1963 to July 1966. Ditko left after the 38th issue, while Lee remained as writer until issue 100. Since then, many writers and artists have taken over the monthly comic through the years, chronicling the adventures of Marvel's most identifiable hero. The Amazing Spider-Man has been the character's flagship series for his first fifty years in publication, and was the only monthly series to star Spider-Man until Peter Parker, The Spectacular Spider-Man, in 1976, although 1972 saw the debut of Marvel Team-Up, with the vast majority of issues featuring Spider-Man along with a rotating cast of other Marvel characters. Most of the major characters and villains of the Spider-Man saga have been introduced in Amazing, and with few exceptions, it is where most key events in the character's history have occurred. The title was published continuously until No. 441 (Nov. 1998) when Marvel Comics relaunched it as vol. 2 No. 1 (Jan. 1999), but on Spider-Man's 40th anniversary, this new title reverted to using the numbering of the original series, beginning again with issue No. 500 (Dec. 2003) and lasting until the final issue, No. 700 (Feb. 2013). 1960s Due to strong sales on the character's first appearance in Amazing Fantasy No. 15, Spider-Man was given his own ongoing series in March 1963. The initial years of the series, under Lee and Ditko, chronicled Spider-Man's nascent career as a masked super-human vigilante with his civilian life as hard-luck yet perpetually good-humored and well-meaning teenager Peter Parker.

Peter balanced his career as Spider-Man with his job as a freelance photographer for The Daily Bugle under the bombastic editor-publisher J. Jonah Jameson to support himself and his frail Aunt May. At the same time, Peter dealt with public hostility towards Spider-Man and the antagonism of his classmates Flash Thompson and Liz Allan at Midtown High School, while embarking on a tentative, ill-fated romance with Jameson's secretary, Betty Brant. By focusing on Parker's everyday problems, Lee and Ditko created a groundbreakingly flawed, self-doubting superhero, and the first major teenaged superhero to be a protagonist and not a sidekick. Ditko's quirky art provided a stark contrast to the more cleanly dynamic stylings of Marvel's most prominent artist, Jack Kirby, and combined with the humor and pathos of Lee's writing to lay the foundation for what became an enduring mythos. Most of Spider-Man's key villains and supporting characters were introduced during this time. Issue No. 1 (March 1963) featured the first appearances of J. Jonah Jameson and his astronaut son John Jameson, and the supervillain the Chameleon. It included the hero's first encounter with the superhero team the Fantastic Four. Issue No. 2 (May 1963) featured the first appearance of the Vulture and the Tinkerer as well as the beginning of Parker's freelance photography career at the newspaper The Daily Bugle. The Lee-Ditko era continued to usher in a significant number of villains and supporting characters, including Doctor Octopus in No. 3 (July 1963); the Sandman and Betty Brant in No. 4 (Sept. 1963); the Lizard in No. 6 (Nov. 1963); Living Brain in (#8, January 1964); Electro in No. 9 (March 1964); Mysterio in No. 13 (June 1964); the Green Goblin in No. 14 (July 1964); Kraven The Hunter in No. 15 (Aug. 1964); reporter Ned Leeds in No. 18 (Nov. 1964); and the Scorpion in No. 20 (Jan. 1965). The Molten Man was introduced in No. 28 (Sept. 1965) which also featured Parker's graduation from high school. Peter began attending Empire State University in No. 31 (Dec. 1965), the issue which featured the first appearances of friends and classmates Gwen Stacy and Harry Osborn. Harry's father, Norman Osborn first appeared in No. 23 (April 1965) as a member of Jameson's country club but is not named nor revealed as Harry's father until No. 37 (June 1966). One of the most celebrated issues of the Lee-Ditko run is No. 33 (Feb. 1966), the third part of the story arc "If This Be My Destiny...! ", which features the dramatic scene of Spider-Man, through force of will and thoughts of family, escaping from being pinned by heavy machinery. Comics historian Les Daniels noted that "Steve Ditko squeezes every ounce of anguish out of Spider-Man's predicament, complete with visions of the uncle he failed and the aunt he has sworn to save." Peter David observed that "After his origin, this two-page sequence from Amazing Spider-Man No. 33 is perhaps the best-loved sequence from the Stan Lee/Steve Ditko era."

Peter balanced his career as Spider-Man with his job as a freelance photographer for The Daily Bugle under the bombastic editor-publisher J. Jonah Jameson to support himself and his frail Aunt May. At the same time, Peter dealt with public hostility towards Spider-Man and the antagonism of his classmates Flash Thompson and Liz Allan at Midtown High School, while embarking on a tentative, ill-fated romance with Jameson's secretary, Betty Brant. By focusing on Parker's everyday problems, Lee and Ditko created a groundbreakingly flawed, self-doubting superhero, and the first major teenaged superhero to be a protagonist and not a sidekick. Ditko's quirky art provided a stark contrast to the more cleanly dynamic stylings of Marvel's most prominent artist, Jack Kirby, and combined with the humor and pathos of Lee's writing to lay the foundation for what became an enduring mythos. Most of Spider-Man's key villains and supporting characters were introduced during this time. Issue No. 1 (March 1963) featured the first appearances of J. Jonah Jameson and his astronaut son John Jameson, and the supervillain the Chameleon. It included the hero's first encounter with the superhero team the Fantastic Four. Issue No. 2 (May 1963) featured the first appearance of the Vulture and the Tinkerer as well as the beginning of Parker's freelance photography career at the newspaper The Daily Bugle. The Lee-Ditko era continued to usher in a significant number of villains and supporting characters, including Doctor Octopus in No. 3 (July 1963); the Sandman and Betty Brant in No. 4 (Sept. 1963); the Lizard in No. 6 (Nov. 1963); Living Brain in (#8, January 1964); Electro in No. 9 (March 1964); Mysterio in No. 13 (June 1964); the Green Goblin in No. 14 (July 1964); Kraven The Hunter in No. 15 (Aug. 1964); reporter Ned Leeds in No. 18 (Nov. 1964); and the Scorpion in No. 20 (Jan. 1965). The Molten Man was introduced in No. 28 (Sept. 1965) which also featured Parker's graduation from high school. Peter began attending Empire State University in No. 31 (Dec. 1965), the issue which featured the first appearances of friends and classmates Gwen Stacy and Harry Osborn. Harry's father, Norman Osborn first appeared in No. 23 (April 1965) as a member of Jameson's country club but is not named nor revealed as Harry's father until No. 37 (June 1966). One of the most celebrated issues of the Lee-Ditko run is No. 33 (Feb. 1966), the third part of the story arc "If This Be My Destiny...! ", which features the dramatic scene of Spider-Man, through force of will and thoughts of family, escaping from being pinned by heavy machinery. Comics historian Les Daniels noted that "Steve Ditko squeezes every ounce of anguish out of Spider-Man's predicament, complete with visions of the uncle he failed and the aunt he has sworn to save." Peter David observed that "After his origin, this two-page sequence from Amazing Spider-Man No. 33 is perhaps the best-loved sequence from the Stan Lee/Steve Ditko era."

Peter balanced his career as Spider-Man with his job as a freelance photographer for The Daily Bugle under the bombastic editor-publisher J. Jonah Jameson to support himself and his frail Aunt May. At the same time, Peter dealt with public hostility towards Spider-Man and the antagonism of his classmates Flash Thompson and Liz Allan at Midtown High School, while embarking on a tentative, ill-fated romance with Jameson's secretary, Betty Brant. By focusing on Parker's everyday problems, Lee and Ditko created a groundbreakingly flawed, self-doubting superhero, and the first major teenaged superhero to be a protagonist and not a sidekick. Ditko's quirky art provided a stark contrast to the more cleanly dynamic stylings of Marvel's most prominent artist, Jack Kirby, and combined with the humor and pathos of Lee's writing to lay the foundation for what became an enduring mythos. Most of Spider-Man's key villains and supporting characters were introduced during this time. Issue No. 1 (March 1963) featured the first appearances of J. Jonah Jameson and his astronaut son John Jameson, and the supervillain the Chameleon. It included the hero's first encounter with the superhero team the Fantastic Four. Issue No. 2 (May 1963) featured the first appearance of the Vulture and the Tinkerer as well as the beginning of Parker's freelance photography career at the newspaper The Daily Bugle. The Lee-Ditko era continued to usher in a significant number of villains and supporting characters, including Doctor Octopus in No. 3 (July 1963); the Sandman and Betty Brant in No. 4 (Sept. 1963); the Lizard in No. 6 (Nov. 1963); Living Brain in (#8, January 1964); Electro in No. 9 (March 1964); Mysterio in No. 13 (June 1964); the Green Goblin in No. 14 (July 1964); Kraven The Hunter in No. 15 (Aug. 1964); reporter Ned Leeds in No. 18 (Nov. 1964); and the Scorpion in No. 20 (Jan. 1965). The Molten Man was introduced in No. 28 (Sept. 1965) which also featured Parker's graduation from high school. Peter began attending Empire State University in No. 31 (Dec. 1965), the issue which featured the first appearances of friends and classmates Gwen Stacy and Harry Osborn. Harry's father, Norman Osborn first appeared in No. 23 (April 1965) as a member of Jameson's country club but is not named nor revealed as Harry's father until No. 37 (June 1966). One of the most celebrated issues of the Lee-Ditko run is No. 33 (Feb. 1966), the third part of the story arc "If This Be My Destiny...! ", which features the dramatic scene of Spider-Man, through force of will and thoughts of family, escaping from being pinned by heavy machinery. Comics historian Les Daniels noted that "Steve Ditko squeezes every ounce of anguish out of Spider-Man's predicament, complete with visions of the uncle he failed and the aunt he has sworn to save." Peter David observed that "After his origin, this two-page sequence from Amazing Spider-Man No. 33 is perhaps the best-loved sequence from the Stan Lee/Steve Ditko era."

Steve Saffel stated the "full page Ditko image from The Amazing Spider-Man No. 33 is one of the most powerful ever to appear in the series and influenced writers and artists for many years to come." and Matthew K. Manning wrote that "Ditko's illustrations for the first few pages of this Lee story included what would become one of the most iconic scenes in Spider-Man's history." The story was chosen as No. 15 in the 100 Greatest Marvels of All Time poll of Marvel's readers in 2001. Editor Robert Greenberger wrote in his introduction to the story that "These first five pages are a modern-day equivalent to Shakespeare as Parker's soliloquy sets the stage for his next action. And with dramatic pacing and storytelling, Ditko delivers one of the great sequences in all comics." Although credited only as artist for most of his run, Ditko would eventually plot the stories as well as draw them, leaving Lee to script the dialogue. A rift between Ditko and Lee developed, and the two men were not on speaking terms long before Ditko completed his last issue, The Amazing Spider-Man No. 38 (July 1966). The exact reasons for the Ditko-Lee split have never been fully explained. Spider-Man successor artist John Romita Sr., in a 2010 deposition, recalled that Lee and Ditko "ended up not being able to work together because they disagreed on almost everything, cultural, social, historically, everything, they disagreed on characters..." In successor penciler Romita Sr.'s first issue, No. 39 (Aug. 1966), nemesis the Green Goblin discovers Spider-Man's secret identity and reveals his own to the captive hero. Romita's Spider-Man – more polished and heroic-looking than Ditko's – became the model for two decades. The Lee-Romita era saw the introduction of such characters as Daily Bugle managing editor Robbie Robertson in No. 52 (Sept. 1967) and NYPD Captain George Stacy, father of Parker's girlfriend Gwen Stacy, in No. 56 (Jan. 1968). The most important supporting character to be introduced during the Romita era was Mary Jane Watson, who made her first full appearance in No. 42, (Nov. 1966), although she first appeared in No. 25 (June 1965) with her face obscured and had been mentioned since No. 15 (Aug. 1964). Peter David wrote in 2010 that Romita "made the definitive statement of his arrival by pulling Mary Jane out from behind the oversized potted plant [that blocked the readers' view of her face in issue #25] and placing her on panel in what would instantly become an iconic moment." Romita has stated that in designing Mary Jane, he "used Ann-Margret from the movie Bye Bye Birdie as a guide, using her coloring, the shape of her face, her red hair and her form-fitting short skirts." Lee and Romita toned down the prevalent sense of antagonism in Parker's world by improving Parker's relationship with the supporting characters and having stories focused as much on the social and college lives of the characters as they did on Spider-Man's adventures.

Steve Saffel stated the "full page Ditko image from The Amazing Spider-Man No. 33 is one of the most powerful ever to appear in the series and influenced writers and artists for many years to come." and Matthew K. Manning wrote that "Ditko's illustrations for the first few pages of this Lee story included what would become one of the most iconic scenes in Spider-Man's history." The story was chosen as No. 15 in the 100 Greatest Marvels of All Time poll of Marvel's readers in 2001. Editor Robert Greenberger wrote in his introduction to the story that "These first five pages are a modern-day equivalent to Shakespeare as Parker's soliloquy sets the stage for his next action. And with dramatic pacing and storytelling, Ditko delivers one of the great sequences in all comics." Although credited only as artist for most of his run, Ditko would eventually plot the stories as well as draw them, leaving Lee to script the dialogue. A rift between Ditko and Lee developed, and the two men were not on speaking terms long before Ditko completed his last issue, The Amazing Spider-Man No. 38 (July 1966). The exact reasons for the Ditko-Lee split have never been fully explained. Spider-Man successor artist John Romita Sr., in a 2010 deposition, recalled that Lee and Ditko "ended up not being able to work together because they disagreed on almost everything, cultural, social, historically, everything, they disagreed on characters..." In successor penciler Romita Sr.'s first issue, No. 39 (Aug. 1966), nemesis the Green Goblin discovers Spider-Man's secret identity and reveals his own to the captive hero. Romita's Spider-Man – more polished and heroic-looking than Ditko's – became the model for two decades. The Lee-Romita era saw the introduction of such characters as Daily Bugle managing editor Robbie Robertson in No. 52 (Sept. 1967) and NYPD Captain George Stacy, father of Parker's girlfriend Gwen Stacy, in No. 56 (Jan. 1968). The most important supporting character to be introduced during the Romita era was Mary Jane Watson, who made her first full appearance in No. 42, (Nov. 1966), although she first appeared in No. 25 (June 1965) with her face obscured and had been mentioned since No. 15 (Aug. 1964). Peter David wrote in 2010 that Romita "made the definitive statement of his arrival by pulling Mary Jane out from behind the oversized potted plant [that blocked the readers' view of her face in issue #25] and placing her on panel in what would instantly become an iconic moment." Romita has stated that in designing Mary Jane, he "used Ann-Margret from the movie Bye Bye Birdie as a guide, using her coloring, the shape of her face, her red hair and her form-fitting short skirts." Lee and Romita toned down the prevalent sense of antagonism in Parker's world by improving Parker's relationship with the supporting characters and having stories focused as much on the social and college lives of the characters as they did on Spider-Man's adventures.

Steve Saffel stated the "full page Ditko image from The Amazing Spider-Man No. 33 is one of the most powerful ever to appear in the series and influenced writers and artists for many years to come." and Matthew K. Manning wrote that "Ditko's illustrations for the first few pages of this Lee story included what would become one of the most iconic scenes in Spider-Man's history." The story was chosen as No. 15 in the 100 Greatest Marvels of All Time poll of Marvel's readers in 2001. Editor Robert Greenberger wrote in his introduction to the story that "These first five pages are a modern-day equivalent to Shakespeare as Parker's soliloquy sets the stage for his next action. And with dramatic pacing and storytelling, Ditko delivers one of the great sequences in all comics." Although credited only as artist for most of his run, Ditko would eventually plot the stories as well as draw them, leaving Lee to script the dialogue. A rift between Ditko and Lee developed, and the two men were not on speaking terms long before Ditko completed his last issue, The Amazing Spider-Man No. 38 (July 1966). The exact reasons for the Ditko-Lee split have never been fully explained. Spider-Man successor artist John Romita Sr., in a 2010 deposition, recalled that Lee and Ditko "ended up not being able to work together because they disagreed on almost everything, cultural, social, historically, everything, they disagreed on characters..." In successor penciler Romita Sr.'s first issue, No. 39 (Aug. 1966), nemesis the Green Goblin discovers Spider-Man's secret identity and reveals his own to the captive hero. Romita's Spider-Man – more polished and heroic-looking than Ditko's – became the model for two decades. The Lee-Romita era saw the introduction of such characters as Daily Bugle managing editor Robbie Robertson in No. 52 (Sept. 1967) and NYPD Captain George Stacy, father of Parker's girlfriend Gwen Stacy, in No. 56 (Jan. 1968). The most important supporting character to be introduced during the Romita era was Mary Jane Watson, who made her first full appearance in No. 42, (Nov. 1966), although she first appeared in No. 25 (June 1965) with her face obscured and had been mentioned since No. 15 (Aug. 1964). Peter David wrote in 2010 that Romita "made the definitive statement of his arrival by pulling Mary Jane out from behind the oversized potted plant [that blocked the readers' view of her face in issue #25] and placing her on panel in what would instantly become an iconic moment." Romita has stated that in designing Mary Jane, he "used Ann-Margret from the movie Bye Bye Birdie as a guide, using her coloring, the shape of her face, her red hair and her form-fitting short skirts." Lee and Romita toned down the prevalent sense of antagonism in Parker's world by improving Parker's relationship with the supporting characters and having stories focused as much on the social and college lives of the characters as they did on Spider-Man's adventures.

The stories became more topical, addressing issues such as civil rights, racism, prisoners' rights, the Vietnam War, and political elections. Issue No. 50 (June 1967) introduced the highly enduring criminal mastermind the Kingpin, who would become a major force as well in the superhero series Daredevil. Other notable first appearances in the Lee-Romita era include the Rhino in No. 41 (Oct. 1966), the Shocker in No. 46 (March 1967), the Prowler in No. 78 (Nov. 1969), and the Kingpin's son, Richard Fisk, in No. 83 (April 1970). 1970s Several spin-off series debuted in the 1970s: Marvel Team-Up in 1972, and The Spectacular Spider-Man in 1976. A short-lived series titled Giant-Size Spider-Man began in July 1974 and ran six issues through 1975. Spidey Super Stories, a series aimed at children ages 6–10, ran for 57 issues from October 1974 through 1982. The flagship title's second decade took a grim turn with a story in #89-90 (Oct.-Nov. 1970) featuring the death of Captain George Stacy. This was the first Spider-Man story to be penciled by Gil Kane, who would alternate drawing duties with Romita for the next year-and-a-half and would draw several landmark issues. One such story took place in the controversial issues #96–98 (May–July 1971). Writer-editor Lee defied the Comics Code Authority with this story, in which Parker's friend Harry Osborn, was hospitalized after over-dosing on pills. Lee wrote this story upon a request from the U. S. Department of Health, Education, and Welfare for a story about the dangers of drugs. Citing its dictum against depicting drug use, even in an anti-drug context, the CCA refused to put its seal on these issues. With the approval of Marvel publisher Martin Goodman, Lee had the comics published without the seal. The comics sold well and Marvel won praise for its socially conscious efforts. The CCA subsequently loosened the Code to permit negative depictions of drugs, among other new freedoms. "The Six Arms Saga" of #100–102 (Sept.–Nov. 1971) introduced Morbius, the Living Vampire. The second installment was the first Amazing Spider-Man story not written by co-creator Lee, with Roy Thomas taking over writing the book for several months before Lee returned to write #105–110 (Feb.-July 1972). Lee, who was going on to become Marvel Comics' publisher, with Thomas becoming editor-in-chief, then turned writing duties over to 19-year-old Gerry Conway, who scripted the series through 1975. Romita penciled Conway's first half-dozen issues, which introduced the gangster Hammerhead in No. 113 (Oct. 1972). Kane then succeeded Romita as penciler, although Romita would continue inking Kane for a time. Issues 121–122 (June–July 1973, by Conway-Kane-Romita), which featured the death of Gwen Stacy at the hands of the Green Goblin in "The Night Gwen Stacy Died" in issue No. 121. Her demise and the Goblin's apparent death one issue later formed a story arc widely considered as the most defining in the history of Spider-Man. The aftermath of the story deepened both the characterization of Mary Jane Watson and her relationship with Parker.

The stories became more topical, addressing issues such as civil rights, racism, prisoners' rights, the Vietnam War, and political elections. Issue No. 50 (June 1967) introduced the highly enduring criminal mastermind the Kingpin, who would become a major force as well in the superhero series Daredevil. Other notable first appearances in the Lee-Romita era include the Rhino in No. 41 (Oct. 1966), the Shocker in No. 46 (March 1967), the Prowler in No. 78 (Nov. 1969), and the Kingpin's son, Richard Fisk, in No. 83 (April 1970). 1970s Several spin-off series debuted in the 1970s: Marvel Team-Up in 1972, and The Spectacular Spider-Man in 1976. A short-lived series titled Giant-Size Spider-Man began in July 1974 and ran six issues through 1975. Spidey Super Stories, a series aimed at children ages 6–10, ran for 57 issues from October 1974 through 1982. The flagship title's second decade took a grim turn with a story in #89-90 (Oct.-Nov. 1970) featuring the death of Captain George Stacy. This was the first Spider-Man story to be penciled by Gil Kane, who would alternate drawing duties with Romita for the next year-and-a-half and would draw several landmark issues. One such story took place in the controversial issues #96–98 (May–July 1971). Writer-editor Lee defied the Comics Code Authority with this story, in which Parker's friend Harry Osborn, was hospitalized after over-dosing on pills. Lee wrote this story upon a request from the U. S. Department of Health, Education, and Welfare for a story about the dangers of drugs. Citing its dictum against depicting drug use, even in an anti-drug context, the CCA refused to put its seal on these issues. With the approval of Marvel publisher Martin Goodman, Lee had the comics published without the seal. The comics sold well and Marvel won praise for its socially conscious efforts. The CCA subsequently loosened the Code to permit negative depictions of drugs, among other new freedoms. "The Six Arms Saga" of #100–102 (Sept.–Nov. 1971) introduced Morbius, the Living Vampire. The second installment was the first Amazing Spider-Man story not written by co-creator Lee, with Roy Thomas taking over writing the book for several months before Lee returned to write #105–110 (Feb.-July 1972). Lee, who was going on to become Marvel Comics' publisher, with Thomas becoming editor-in-chief, then turned writing duties over to 19-year-old Gerry Conway, who scripted the series through 1975. Romita penciled Conway's first half-dozen issues, which introduced the gangster Hammerhead in No. 113 (Oct. 1972). Kane then succeeded Romita as penciler, although Romita would continue inking Kane for a time. Issues 121–122 (June–July 1973, by Conway-Kane-Romita), which featured the death of Gwen Stacy at the hands of the Green Goblin in "The Night Gwen Stacy Died" in issue No. 121. Her demise and the Goblin's apparent death one issue later formed a story arc widely considered as the most defining in the history of Spider-Man. The aftermath of the story deepened both the characterization of Mary Jane Watson and her relationship with Parker.

The stories became more topical, addressing issues such as civil rights, racism, prisoners' rights, the Vietnam War, and political elections. Issue No. 50 (June 1967) introduced the highly enduring criminal mastermind the Kingpin, who would become a major force as well in the superhero series Daredevil. Other notable first appearances in the Lee-Romita era include the Rhino in No. 41 (Oct. 1966), the Shocker in No. 46 (March 1967), the Prowler in No. 78 (Nov. 1969), and the Kingpin's son, Richard Fisk, in No. 83 (April 1970). 1970s Several spin-off series debuted in the 1970s: Marvel Team-Up in 1972, and The Spectacular Spider-Man in 1976. A short-lived series titled Giant-Size Spider-Man began in July 1974 and ran six issues through 1975. Spidey Super Stories, a series aimed at children ages 6–10, ran for 57 issues from October 1974 through 1982. The flagship title's second decade took a grim turn with a story in #89-90 (Oct.-Nov. 1970) featuring the death of Captain George Stacy. This was the first Spider-Man story to be penciled by Gil Kane, who would alternate drawing duties with Romita for the next year-and-a-half and would draw several landmark issues. One such story took place in the controversial issues #96–98 (May–July 1971). Writer-editor Lee defied the Comics Code Authority with this story, in which Parker's friend Harry Osborn, was hospitalized after over-dosing on pills. Lee wrote this story upon a request from the U. S. Department of Health, Education, and Welfare for a story about the dangers of drugs. Citing its dictum against depicting drug use, even in an anti-drug context, the CCA refused to put its seal on these issues. With the approval of Marvel publisher Martin Goodman, Lee had the comics published without the seal. The comics sold well and Marvel won praise for its socially conscious efforts. The CCA subsequently loosened the Code to permit negative depictions of drugs, among other new freedoms. "The Six Arms Saga" of #100–102 (Sept.–Nov. 1971) introduced Morbius, the Living Vampire. The second installment was the first Amazing Spider-Man story not written by co-creator Lee, with Roy Thomas taking over writing the book for several months before Lee returned to write #105–110 (Feb.-July 1972). Lee, who was going on to become Marvel Comics' publisher, with Thomas becoming editor-in-chief, then turned writing duties over to 19-year-old Gerry Conway, who scripted the series through 1975. Romita penciled Conway's first half-dozen issues, which introduced the gangster Hammerhead in No. 113 (Oct. 1972). Kane then succeeded Romita as penciler, although Romita would continue inking Kane for a time. Issues 121–122 (June–July 1973, by Conway-Kane-Romita), which featured the death of Gwen Stacy at the hands of the Green Goblin in "The Night Gwen Stacy Died" in issue No. 121. Her demise and the Goblin's apparent death one issue later formed a story arc widely considered as the most defining in the history of Spider-Man. The aftermath of the story deepened both the characterization of Mary Jane Watson and her relationship with Parker.

In 1973, Gil Kane was succeeded by Ross Andru, whose run lasted from issue No. 125 (October 1973) to No. 185 (October 1978). Issue#129 (Feb. 1974) introduced the Punisher, who would become one of Marvel Comics' most popular characters. The Conway-Andru era featured the first appearances of the Man-Wolf in #124–125 (Sept.-Oct. 1973); the near-marriage of Doctor Octopus and Aunt May in No. 131 (April 1974); Harry Osborn stepping into his father's role as the Green Goblin in #135–137 (Aug.-Oct.1974); and the original "Clone Saga", containing the introduction of Spider-Man's clone, in #147–149 (Aug.-Oct. 1975). Archie Goodwin and Gil Kane produced the title's 150th issue (Nov. 1975) before Len Wein became writer with issue No. 151. During Wein's tenure, Harry Osborn and Liz Allen dated and became engaged; J. Jonah Jameson was introduced to his eventual second wife, Marla Madison; and Aunt May suffered a heart attack. Wein's last story on Amazing was a five-issue arc in #176–180 (Jan.-May 1978) featuring a third Green Goblin (Harry Osborn's psychiatrist, Bart Hamilton). Marv Wolfman, Marvel's editor-in-chief from 1975 to 1976, succeeded Wein as writer, and in his first issue, No. 182 (July 1978), had Parker propose marriage to Watson who refused, in the following issue. Keith Pollard succeeded Ross Andru as artist shortly afterward, and with Wolfman introduced the likable rogue the Black Cat (Felicia Hardy) in No. 194 (July 1979). As a love interest for Spider-Man, the Black Cat would go on to be an important supporting character for the better part of the next decade, and remain a friend and occasional lover into the 2010s. 1980s The Amazing Spider-Man No. 200 (Jan. 1980) featured the return and death of the burglar who killed Spider-Man's Uncle Ben. Writer Marv Wolfman and penciler Keith Pollard both left the title by mid-year, succeeded by Dennis O'Neil, a writer known for groundbreaking 1970s work at rival DC Comics, and penciler John Romita Jr. O'Neil wrote two issues of The Amazing Spider-Man Annual which were both drawn by Frank Miller. The 1980 Annual featured a team-up with Doctor Strange while the 1981 Annual showcased a meeting with the Punisher. Roger Stern, who had written nearly 20 issues of sister title The Spectacular Spider-Man, took over Amazing with issue No. 224 (January 1982). During his two years on the title, Stern augmented the backgrounds of long-established Spider-Man villains, and with Romita Jr. created the mysterious supervillain the Hobgoblin in #238–239 (March–April 1983). Fans engaged with the mystery of the Hobgoblin's secret identity, which continued throughout #244–245 and 249–251 (Sept.-Oct. 1983 and Feb.-April 1984). One lasting change was the reintroduction of Mary Jane Watson as a more serious, mature woman who becomes Peter's confidante after she reveals that she knows his secret identity. Stern also wrote "The Kid Who Collects Spider-Man" in The Amazing Spider-Man No. 248 (January 1984), a story which ranks among his most popular. By mid-1984, Tom DeFalco and Ron Frenz took over scripting and penciling.

In 1973, Gil Kane was succeeded by Ross Andru, whose run lasted from issue No. 125 (October 1973) to No. 185 (October 1978). Issue#129 (Feb. 1974) introduced the Punisher, who would become one of Marvel Comics' most popular characters. The Conway-Andru era featured the first appearances of the Man-Wolf in #124–125 (Sept.-Oct. 1973); the near-marriage of Doctor Octopus and Aunt May in No. 131 (April 1974); Harry Osborn stepping into his father's role as the Green Goblin in #135–137 (Aug.-Oct.1974); and the original "Clone Saga", containing the introduction of Spider-Man's clone, in #147–149 (Aug.-Oct. 1975). Archie Goodwin and Gil Kane produced the title's 150th issue (Nov. 1975) before Len Wein became writer with issue No. 151. During Wein's tenure, Harry Osborn and Liz Allen dated and became engaged; J. Jonah Jameson was introduced to his eventual second wife, Marla Madison; and Aunt May suffered a heart attack. Wein's last story on Amazing was a five-issue arc in #176–180 (Jan.-May 1978) featuring a third Green Goblin (Harry Osborn's psychiatrist, Bart Hamilton). Marv Wolfman, Marvel's editor-in-chief from 1975 to 1976, succeeded Wein as writer, and in his first issue, No. 182 (July 1978), had Parker propose marriage to Watson who refused, in the following issue. Keith Pollard succeeded Ross Andru as artist shortly afterward, and with Wolfman introduced the likable rogue the Black Cat (Felicia Hardy) in No. 194 (July 1979). As a love interest for Spider-Man, the Black Cat would go on to be an important supporting character for the better part of the next decade, and remain a friend and occasional lover into the 2010s. 1980s The Amazing Spider-Man No. 200 (Jan. 1980) featured the return and death of the burglar who killed Spider-Man's Uncle Ben. Writer Marv Wolfman and penciler Keith Pollard both left the title by mid-year, succeeded by Dennis O'Neil, a writer known for groundbreaking 1970s work at rival DC Comics, and penciler John Romita Jr. O'Neil wrote two issues of The Amazing Spider-Man Annual which were both drawn by Frank Miller. The 1980 Annual featured a team-up with Doctor Strange while the 1981 Annual showcased a meeting with the Punisher. Roger Stern, who had written nearly 20 issues of sister title The Spectacular Spider-Man, took over Amazing with issue No. 224 (January 1982). During his two years on the title, Stern augmented the backgrounds of long-established Spider-Man villains, and with Romita Jr. created the mysterious supervillain the Hobgoblin in #238–239 (March–April 1983). Fans engaged with the mystery of the Hobgoblin's secret identity, which continued throughout #244–245 and 249–251 (Sept.-Oct. 1983 and Feb.-April 1984). One lasting change was the reintroduction of Mary Jane Watson as a more serious, mature woman who becomes Peter's confidante after she reveals that she knows his secret identity. Stern also wrote "The Kid Who Collects Spider-Man" in The Amazing Spider-Man No. 248 (January 1984), a story which ranks among his most popular. By mid-1984, Tom DeFalco and Ron Frenz took over scripting and penciling.

In 1973, Gil Kane was succeeded by Ross Andru, whose run lasted from issue No. 125 (October 1973) to No. 185 (October 1978). Issue#129 (Feb. 1974) introduced the Punisher, who would become one of Marvel Comics' most popular characters. The Conway-Andru era featured the first appearances of the Man-Wolf in #124–125 (Sept.-Oct. 1973); the near-marriage of Doctor Octopus and Aunt May in No. 131 (April 1974); Harry Osborn stepping into his father's role as the Green Goblin in #135–137 (Aug.-Oct.1974); and the original "Clone Saga", containing the introduction of Spider-Man's clone, in #147–149 (Aug.-Oct. 1975). Archie Goodwin and Gil Kane produced the title's 150th issue (Nov. 1975) before Len Wein became writer with issue No. 151. During Wein's tenure, Harry Osborn and Liz Allen dated and became engaged; J. Jonah Jameson was introduced to his eventual second wife, Marla Madison; and Aunt May suffered a heart attack. Wein's last story on Amazing was a five-issue arc in #176–180 (Jan.-May 1978) featuring a third Green Goblin (Harry Osborn's psychiatrist, Bart Hamilton). Marv Wolfman, Marvel's editor-in-chief from 1975 to 1976, succeeded Wein as writer, and in his first issue, No. 182 (July 1978), had Parker propose marriage to Watson who refused, in the following issue. Keith Pollard succeeded Ross Andru as artist shortly afterward, and with Wolfman introduced the likable rogue the Black Cat (Felicia Hardy) in No. 194 (July 1979). As a love interest for Spider-Man, the Black Cat would go on to be an important supporting character for the better part of the next decade, and remain a friend and occasional lover into the 2010s. 1980s The Amazing Spider-Man No. 200 (Jan. 1980) featured the return and death of the burglar who killed Spider-Man's Uncle Ben. Writer Marv Wolfman and penciler Keith Pollard both left the title by mid-year, succeeded by Dennis O'Neil, a writer known for groundbreaking 1970s work at rival DC Comics, and penciler John Romita Jr. O'Neil wrote two issues of The Amazing Spider-Man Annual which were both drawn by Frank Miller. The 1980 Annual featured a team-up with Doctor Strange while the 1981 Annual showcased a meeting with the Punisher. Roger Stern, who had written nearly 20 issues of sister title The Spectacular Spider-Man, took over Amazing with issue No. 224 (January 1982). During his two years on the title, Stern augmented the backgrounds of long-established Spider-Man villains, and with Romita Jr. created the mysterious supervillain the Hobgoblin in #238–239 (March–April 1983). Fans engaged with the mystery of the Hobgoblin's secret identity, which continued throughout #244–245 and 249–251 (Sept.-Oct. 1983 and Feb.-April 1984). One lasting change was the reintroduction of Mary Jane Watson as a more serious, mature woman who becomes Peter's confidante after she reveals that she knows his secret identity. Stern also wrote "The Kid Who Collects Spider-Man" in The Amazing Spider-Man No. 248 (January 1984), a story which ranks among his most popular. By mid-1984, Tom DeFalco and Ron Frenz took over scripting and penciling.

DeFalco helped establish Parker and Watson's mature relationship, laying the foundation for the characters' wedding in 1987. Notably, in No. 257 (Oct. 1984), Watson tells Parker that she knows he is Spider-Man, and in No. 259 (Dec. 1984), she reveals to Parker the extent of her troubled childhood. Other notable issues of the DeFalco-Frenz era include No. 252 (May 1984), with the first appearance of Spider-Man's black costume, which the hero would wear almost exclusively for the next four years' worth of comics; the debut of criminal mastermind the Rose, in No. 253 (June 1984); the revelation in No. 258 (Nov. 1984) that the black costume is a living being, a symbiote; and the introduction of the female mercenary Silver Sable in No. 265 (June 1985). Tom DeFalco and Ron Frenz were both removed from The Amazing Spider-Man in 1986 by editor Jim Owsley under acrimonious circumstances. A succession of artists including Alan Kupperberg, John Romita Jr., and Alex Saviuk penciled the series from 1987 to 1988; Owsley wrote the book for the first half of 1987, scripting the five-part "Gang War" story (#284–288) that DeFalco plotted. Former Spectacular Spider-Man writer Peter David scripted No. 289 (June 1987), which revealed Ned Leeds as being the Hobgoblin although this was retconned in 1996 by Roger Stern into Leeds not being the original Hobgoblin after all. David Michelinie took over as writer in the next issue, for a story arc in #290–292 (July–Sept. 1987) that led to the marriage of Peter Parker and Mary Jane Watson in Amazing Spider-Man Annual No. 21. The "Kraven's Last Hunt" storyline by writer J.M. DeMatteis and artists Mike Zeck and Bob McLeod crossed over into The Amazing Spider-Man No. 293 and 294. Issue No. 298 (March 1988) was the first Spider-Man comic to be drawn by future industry star Todd McFarlane, the first regular artist on The Amazing Spider-Man since Frenz's departure. McFarlane revolutionized Spider-Man's look. His depiction – "Ditko-esque" poses, large-eyed, with wiry, contorted limbs, and messy, knotted, convoluted webbing – influenced the way virtually all subsequent artists would draw the character. McFarlane's other significant contribution to the Spider-Man canon was the design for what would become one of Spider-Man's most wildly popular antagonists, the supervillain Venom. Issue No. 299 (April 1988) featured Venom's first appearance (a last-page cameo) before his first full appearance in No. 300 (May 1988). The latter issue featured Spider-Man reverting to his original red-and-blue costume. Other notable issues of the Michelinie-McFarlane era include No. 312 (Feb. 1989), featuring the Green Goblin vs. the Hobgoblin; and #315–317 (May–July 1989), with the return of Venom. In July 2012, Todd McFarlane's original cover art for The Amazing Spider-Man No. 328 sold for a bid of $657,250, making it the most expensive American comic book art ever sold at auction. 1990s With a civilian life as a married man, the Spider-Man of the 1990s was different from the superhero of the previous three decades.

DeFalco helped establish Parker and Watson's mature relationship, laying the foundation for the characters' wedding in 1987. Notably, in No. 257 (Oct. 1984), Watson tells Parker that she knows he is Spider-Man, and in No. 259 (Dec. 1984), she reveals to Parker the extent of her troubled childhood. Other notable issues of the DeFalco-Frenz era include No. 252 (May 1984), with the first appearance of Spider-Man's black costume, which the hero would wear almost exclusively for the next four years' worth of comics; the debut of criminal mastermind the Rose, in No. 253 (June 1984); the revelation in No. 258 (Nov. 1984) that the black costume is a living being, a symbiote; and the introduction of the female mercenary Silver Sable in No. 265 (June 1985). Tom DeFalco and Ron Frenz were both removed from The Amazing Spider-Man in 1986 by editor Jim Owsley under acrimonious circumstances. A succession of artists including Alan Kupperberg, John Romita Jr., and Alex Saviuk penciled the series from 1987 to 1988; Owsley wrote the book for the first half of 1987, scripting the five-part "Gang War" story (#284–288) that DeFalco plotted. Former Spectacular Spider-Man writer Peter David scripted No. 289 (June 1987), which revealed Ned Leeds as being the Hobgoblin although this was retconned in 1996 by Roger Stern into Leeds not being the original Hobgoblin after all. David Michelinie took over as writer in the next issue, for a story arc in #290–292 (July–Sept. 1987) that led to the marriage of Peter Parker and Mary Jane Watson in Amazing Spider-Man Annual No. 21. The "Kraven's Last Hunt" storyline by writer J.M. DeMatteis and artists Mike Zeck and Bob McLeod crossed over into The Amazing Spider-Man No. 293 and 294. Issue No. 298 (March 1988) was the first Spider-Man comic to be drawn by future industry star Todd McFarlane, the first regular artist on The Amazing Spider-Man since Frenz's departure. McFarlane revolutionized Spider-Man's look. His depiction – "Ditko-esque" poses, large-eyed, with wiry, contorted limbs, and messy, knotted, convoluted webbing – influenced the way virtually all subsequent artists would draw the character. McFarlane's other significant contribution to the Spider-Man canon was the design for what would become one of Spider-Man's most wildly popular antagonists, the supervillain Venom. Issue No. 299 (April 1988) featured Venom's first appearance (a last-page cameo) before his first full appearance in No. 300 (May 1988). The latter issue featured Spider-Man reverting to his original red-and-blue costume. Other notable issues of the Michelinie-McFarlane era include No. 312 (Feb. 1989), featuring the Green Goblin vs. the Hobgoblin; and #315–317 (May–July 1989), with the return of Venom. In July 2012, Todd McFarlane's original cover art for The Amazing Spider-Man No. 328 sold for a bid of $657,250, making it the most expensive American comic book art ever sold at auction. 1990s With a civilian life as a married man, the Spider-Man of the 1990s was different from the superhero of the previous three decades.

DeFalco helped establish Parker and Watson's mature relationship, laying the foundation for the characters' wedding in 1987. Notably, in No. 257 (Oct. 1984), Watson tells Parker that she knows he is Spider-Man, and in No. 259 (Dec. 1984), she reveals to Parker the extent of her troubled childhood. Other notable issues of the DeFalco-Frenz era include No. 252 (May 1984), with the first appearance of Spider-Man's black costume, which the hero would wear almost exclusively for the next four years' worth of comics; the debut of criminal mastermind the Rose, in No. 253 (June 1984); the revelation in No. 258 (Nov. 1984) that the black costume is a living being, a symbiote; and the introduction of the female mercenary Silver Sable in No. 265 (June 1985). Tom DeFalco and Ron Frenz were both removed from The Amazing Spider-Man in 1986 by editor Jim Owsley under acrimonious circumstances. A succession of artists including Alan Kupperberg, John Romita Jr., and Alex Saviuk penciled the series from 1987 to 1988; Owsley wrote the book for the first half of 1987, scripting the five-part "Gang War" story (#284–288) that DeFalco plotted. Former Spectacular Spider-Man writer Peter David scripted No. 289 (June 1987), which revealed Ned Leeds as being the Hobgoblin although this was retconned in 1996 by Roger Stern into Leeds not being the original Hobgoblin after all. David Michelinie took over as writer in the next issue, for a story arc in #290–292 (July–Sept. 1987) that led to the marriage of Peter Parker and Mary Jane Watson in Amazing Spider-Man Annual No. 21. The "Kraven's Last Hunt" storyline by writer J.M. DeMatteis and artists Mike Zeck and Bob McLeod crossed over into The Amazing Spider-Man No. 293 and 294. Issue No. 298 (March 1988) was the first Spider-Man comic to be drawn by future industry star Todd McFarlane, the first regular artist on The Amazing Spider-Man since Frenz's departure. McFarlane revolutionized Spider-Man's look. His depiction – "Ditko-esque" poses, large-eyed, with wiry, contorted limbs, and messy, knotted, convoluted webbing – influenced the way virtually all subsequent artists would draw the character. McFarlane's other significant contribution to the Spider-Man canon was the design for what would become one of Spider-Man's most wildly popular antagonists, the supervillain Venom. Issue No. 299 (April 1988) featured Venom's first appearance (a last-page cameo) before his first full appearance in No. 300 (May 1988). The latter issue featured Spider-Man reverting to his original red-and-blue costume. Other notable issues of the Michelinie-McFarlane era include No. 312 (Feb. 1989), featuring the Green Goblin vs. the Hobgoblin; and #315–317 (May–July 1989), with the return of Venom. In July 2012, Todd McFarlane's original cover art for The Amazing Spider-Man No. 328 sold for a bid of $657,250, making it the most expensive American comic book art ever sold at auction. 1990s With a civilian life as a married man, the Spider-Man of the 1990s was different from the superhero of the previous three decades.

McFarlane left the title in 1990 to write and draw a new series titled simply Spider-Man. His successor, Erik Larsen, penciled the book from early 1990 to mid-1991. After issue No. 350, Larsen was succeeded by Mark Bagley, who had won the 1986 Marvel Tryout Contest and was assigned a number of low-profile penciling jobs followed by a run on New Warriors in 1990. Bagley penciled the flagship Spider-Man title from 1991 to 1996. During that time, Bagley's rendition of Spider-Man was used extensively for licensed material and merchandise. Issues #361–363 (April–June 1992) introduced Carnage, a second symbiote nemesis for Spider-Man. The series' 30th-anniversary issue, No. 365 (Aug. 1992), was a double-sized, hologram-cover issue with the cliffhanger ending of Peter Parker's parents, long thought dead, reappearing alive. It would be close to two years before they were revealed to be impostors, who are killed in No. 388 (April 1994), scripter Michelinie's last issue. His 1987–1994 stint gave him the second-longest run as writer on the title, behind Stan Lee. Issue No. 375 was released with a gold foil cover. There was an error affecting some issues and which are missing the majority of the foil. With No. 389, writer J. M. DeMatteis, whose Spider-Man credits included the 1987 "Kraven's Last Hunt" story arc and a 1991–1993 run on The Spectacular Spider-Man, took over the title. From October 1994 to June 1996, Amazing stopped running stories exclusive to it, and ran installments of multi-part stories that crossed over into all the Spider-Man books. One of the few self-contained stories during this period was in No. 400 (April 1995), which featured the death of Aunt May – later revealed to have been faked (although the death still stands in the MC2 continuity). The "Clone Saga" culminated with the revelation that the Spider-Man who had appeared in the previous 20 years of comics was a clone of the real Spider-Man. This plot twist was massively unpopular with many readers, and was later reversed in the "Revelations" story arc that crossed over the Spider-Man books in late 1996. The Clone Saga tied into a publishing gap after No. 406 (Oct. 1995), when the title was temporarily replaced by The Amazing Scarlet Spider #1–2 (Nov.-Dec. 1995), featuring Ben Reilly. The series picked up again with No. 407 (Jan. 1996), with Tom DeFalco returning as writer. Bagley completed his 5½-year run by September 1996. A succession of artists, including Ron Garney, Steve Skroce, Joe Bennett, Rafael Kayanan and John Byrne penciled the book until the final issue, No. 441 (Nov. 1998), after which Marvel rebooted the title with vol. 2, No. 1 (Jan. 1999). Relaunch and the 2000s Marvel began The Amazing Spider-Man relaunching the 'Amazing' comic book series with (vol. 2) #1 (Jan. 1999). Howard Mackie wrote the first 29 issues. The relaunch included the Sandman being regressed to his criminal ways and the "death" of Mary Jane, which was ultimately reversed.

McFarlane left the title in 1990 to write and draw a new series titled simply Spider-Man. His successor, Erik Larsen, penciled the book from early 1990 to mid-1991. After issue No. 350, Larsen was succeeded by Mark Bagley, who had won the 1986 Marvel Tryout Contest and was assigned a number of low-profile penciling jobs followed by a run on New Warriors in 1990. Bagley penciled the flagship Spider-Man title from 1991 to 1996. During that time, Bagley's rendition of Spider-Man was used extensively for licensed material and merchandise. Issues #361–363 (April–June 1992) introduced Carnage, a second symbiote nemesis for Spider-Man. The series' 30th-anniversary issue, No. 365 (Aug. 1992), was a double-sized, hologram-cover issue with the cliffhanger ending of Peter Parker's parents, long thought dead, reappearing alive. It would be close to two years before they were revealed to be impostors, who are killed in No. 388 (April 1994), scripter Michelinie's last issue. His 1987–1994 stint gave him the second-longest run as writer on the title, behind Stan Lee. Issue No. 375 was released with a gold foil cover. There was an error affecting some issues and which are missing the majority of the foil. With No. 389, writer J. M. DeMatteis, whose Spider-Man credits included the 1987 "Kraven's Last Hunt" story arc and a 1991–1993 run on The Spectacular Spider-Man, took over the title. From October 1994 to June 1996, Amazing stopped running stories exclusive to it, and ran installments of multi-part stories that crossed over into all the Spider-Man books. One of the few self-contained stories during this period was in No. 400 (April 1995), which featured the death of Aunt May – later revealed to have been faked (although the death still stands in the MC2 continuity). The "Clone Saga" culminated with the revelation that the Spider-Man who had appeared in the previous 20 years of comics was a clone of the real Spider-Man. This plot twist was massively unpopular with many readers, and was later reversed in the "Revelations" story arc that crossed over the Spider-Man books in late 1996. The Clone Saga tied into a publishing gap after No. 406 (Oct. 1995), when the title was temporarily replaced by The Amazing Scarlet Spider #1–2 (Nov.-Dec. 1995), featuring Ben Reilly. The series picked up again with No. 407 (Jan. 1996), with Tom DeFalco returning as writer. Bagley completed his 5½-year run by September 1996. A succession of artists, including Ron Garney, Steve Skroce, Joe Bennett, Rafael Kayanan and John Byrne penciled the book until the final issue, No. 441 (Nov. 1998), after which Marvel rebooted the title with vol. 2, No. 1 (Jan. 1999). Relaunch and the 2000s Marvel began The Amazing Spider-Man relaunching the 'Amazing' comic book series with (vol. 2) #1 (Jan. 1999). Howard Mackie wrote the first 29 issues. The relaunch included the Sandman being regressed to his criminal ways and the "death" of Mary Jane, which was ultimately reversed.

McFarlane left the title in 1990 to write and draw a new series titled simply Spider-Man. His successor, Erik Larsen, penciled the book from early 1990 to mid-1991. After issue No. 350, Larsen was succeeded by Mark Bagley, who had won the 1986 Marvel Tryout Contest and was assigned a number of low-profile penciling jobs followed by a run on New Warriors in 1990. Bagley penciled the flagship Spider-Man title from 1991 to 1996. During that time, Bagley's rendition of Spider-Man was used extensively for licensed material and merchandise. Issues #361–363 (April–June 1992) introduced Carnage, a second symbiote nemesis for Spider-Man. The series' 30th-anniversary issue, No. 365 (Aug. 1992), was a double-sized, hologram-cover issue with the cliffhanger ending of Peter Parker's parents, long thought dead, reappearing alive. It would be close to two years before they were revealed to be impostors, who are killed in No. 388 (April 1994), scripter Michelinie's last issue. His 1987–1994 stint gave him the second-longest run as writer on the title, behind Stan Lee. Issue No. 375 was released with a gold foil cover. There was an error affecting some issues and which are missing the majority of the foil. With No. 389, writer J. M. DeMatteis, whose Spider-Man credits included the 1987 "Kraven's Last Hunt" story arc and a 1991–1993 run on The Spectacular Spider-Man, took over the title. From October 1994 to June 1996, Amazing stopped running stories exclusive to it, and ran installments of multi-part stories that crossed over into all the Spider-Man books. One of the few self-contained stories during this period was in No. 400 (April 1995), which featured the death of Aunt May – later revealed to have been faked (although the death still stands in the MC2 continuity). The "Clone Saga" culminated with the revelation that the Spider-Man who had appeared in the previous 20 years of comics was a clone of the real Spider-Man. This plot twist was massively unpopular with many readers, and was later reversed in the "Revelations" story arc that crossed over the Spider-Man books in late 1996. The Clone Saga tied into a publishing gap after No. 406 (Oct. 1995), when the title was temporarily replaced by The Amazing Scarlet Spider #1–2 (Nov.-Dec. 1995), featuring Ben Reilly. The series picked up again with No. 407 (Jan. 1996), with Tom DeFalco returning as writer. Bagley completed his 5½-year run by September 1996. A succession of artists, including Ron Garney, Steve Skroce, Joe Bennett, Rafael Kayanan and John Byrne penciled the book until the final issue, No. 441 (Nov. 1998), after which Marvel rebooted the title with vol. 2, No. 1 (Jan. 1999). Relaunch and the 2000s Marvel began The Amazing Spider-Man relaunching the 'Amazing' comic book series with (vol. 2) #1 (Jan. 1999). Howard Mackie wrote the first 29 issues. The relaunch included the Sandman being regressed to his criminal ways and the "death" of Mary Jane, which was ultimately reversed.

Other elements included the introduction of a new Spider-Woman (who was spun off into her own short-lived series) and references to John Byrne's miniseries Spider-Man: Chapter One, which was launched at the same time as the reboot. Byrne also penciled issues #1–18 (from 1999 to 2000) and wrote #13–14, John Romita Jr. took his place soon after in October 2000. Mackie's run ended with The Amazing Spider-Man Annual 2001, which saw the return of Mary Jane, who then left Parker upon reuniting with him. With issue #30 (June 2001), J. Michael Straczynski took over as writer and oversaw additional storylines – most notably his lengthy "Spider-Totem" arc, which raised the issue of whether Spider-Man's powers were magic-based, rather than as the result of a radioactive spider's bite. Additionally, Straczynski resurrected the plot point of Aunt May discovering her nephew was Spider-Man, and returned Mary Jane, with the couple reuniting in The Amazing Spider-Man (vol. 2) #50. Straczynski gave Spider-Man a new profession, having Parker teach at his former high school. Issue #30 began a dual numbering system, with the original series numbering (#471) returned and placed alongside the volume two number on the cover. Other longtime, rebooted Marvel Comics titles, including Fantastic Four, likewise were given the dual numbering around this time. After (vol. 2) #58 (Nov. 2003), the title reverted completely to its original numbering for issue #500 (Dec. 2003). Mike Deodato, Jr. penciled the series from mid-2004 until 2006. That year Peter Parker revealed his Spider-Man identity on live television in the company-crossover storyline "Civil War", in which the superhero community is split over whether to conform to the federal government's new Superhuman Registration Act. This knowledge was erased from the world with the event of the four-part, crossover story arc, "One More Day", written partially by J. Michael Straczynski and illustrated by Joe Quesada, running through The Amazing Spider-Man #544–545 (Nov.-Dec. 2007), Friendly Neighborhood Spider-Man No. 24 (Nov. 2007) and The Sensational Spider-Man No. 41 (Dec. 2007), the final issues of those two titles. Here, the demon Mephisto makes a Faustian bargain with Parker and Mary Jane, offering to save Parker's dying Aunt May if the couple will allow their marriage to have never existed, rewriting that portion of their pasts. This story arc marked the end of Straczynski's work on the title. Following this, Marvel made The Amazing Spider-Man the company's sole Spider-Man title, increasing its frequency of publication to three issues monthly, and inaugurating the series with a sequence of "back to basics" story arcs under the banner of "Brand New Day". Parker now exists in a changed world where he and Mary Jane had never married, and Parker has no memory of being married to her, with domino effect differences in their immediate world. The most notable of these revisions to Spider-Man continuity are the return of Harry Osborn, whose death in The Spectacular Spider-Man No.

Other elements included the introduction of a new Spider-Woman (who was spun off into her own short-lived series) and references to John Byrne's miniseries Spider-Man: Chapter One, which was launched at the same time as the reboot. Byrne also penciled issues #1–18 (from 1999 to 2000) and wrote #13–14, John Romita Jr. took his place soon after in October 2000. Mackie's run ended with The Amazing Spider-Man Annual 2001, which saw the return of Mary Jane, who then left Parker upon reuniting with him. With issue #30 (June 2001), J. Michael Straczynski took over as writer and oversaw additional storylines – most notably his lengthy "Spider-Totem" arc, which raised the issue of whether Spider-Man's powers were magic-based, rather than as the result of a radioactive spider's bite. Additionally, Straczynski resurrected the plot point of Aunt May discovering her nephew was Spider-Man, and returned Mary Jane, with the couple reuniting in The Amazing Spider-Man (vol. 2) #50. Straczynski gave Spider-Man a new profession, having Parker teach at his former high school. Issue #30 began a dual numbering system, with the original series numbering (#471) returned and placed alongside the volume two number on the cover. Other longtime, rebooted Marvel Comics titles, including Fantastic Four, likewise were given the dual numbering around this time. After (vol. 2) #58 (Nov. 2003), the title reverted completely to its original numbering for issue #500 (Dec. 2003). Mike Deodato, Jr. penciled the series from mid-2004 until 2006. That year Peter Parker revealed his Spider-Man identity on live television in the company-crossover storyline "Civil War", in which the superhero community is split over whether to conform to the federal government's new Superhuman Registration Act. This knowledge was erased from the world with the event of the four-part, crossover story arc, "One More Day", written partially by J. Michael Straczynski and illustrated by Joe Quesada, running through The Amazing Spider-Man #544–545 (Nov.-Dec. 2007), Friendly Neighborhood Spider-Man No. 24 (Nov. 2007) and The Sensational Spider-Man No. 41 (Dec. 2007), the final issues of those two titles. Here, the demon Mephisto makes a Faustian bargain with Parker and Mary Jane, offering to save Parker's dying Aunt May if the couple will allow their marriage to have never existed, rewriting that portion of their pasts. This story arc marked the end of Straczynski's work on the title. Following this, Marvel made The Amazing Spider-Man the company's sole Spider-Man title, increasing its frequency of publication to three issues monthly, and inaugurating the series with a sequence of "back to basics" story arcs under the banner of "Brand New Day". Parker now exists in a changed world where he and Mary Jane had never married, and Parker has no memory of being married to her, with domino effect differences in their immediate world. The most notable of these revisions to Spider-Man continuity are the return of Harry Osborn, whose death in The Spectacular Spider-Man No.

Other elements included the introduction of a new Spider-Woman (who was spun off into her own short-lived series) and references to John Byrne's miniseries Spider-Man: Chapter One, which was launched at the same time as the reboot. Byrne also penciled issues #1–18 (from 1999 to 2000) and wrote #13–14, John Romita Jr. took his place soon after in October 2000. Mackie's run ended with The Amazing Spider-Man Annual 2001, which saw the return of Mary Jane, who then left Parker upon reuniting with him. With issue #30 (June 2001), J. Michael Straczynski took over as writer and oversaw additional storylines – most notably his lengthy "Spider-Totem" arc, which raised the issue of whether Spider-Man's powers were magic-based, rather than as the result of a radioactive spider's bite. Additionally, Straczynski resurrected the plot point of Aunt May discovering her nephew was Spider-Man, and returned Mary Jane, with the couple reuniting in The Amazing Spider-Man (vol. 2) #50. Straczynski gave Spider-Man a new profession, having Parker teach at his former high school. Issue #30 began a dual numbering system, with the original series numbering (#471) returned and placed alongside the volume two number on the cover. Other longtime, rebooted Marvel Comics titles, including Fantastic Four, likewise were given the dual numbering around this time. After (vol. 2) #58 (Nov. 2003), the title reverted completely to its original numbering for issue #500 (Dec. 2003). Mike Deodato, Jr. penciled the series from mid-2004 until 2006. That year Peter Parker revealed his Spider-Man identity on live television in the company-crossover storyline "Civil War", in which the superhero community is split over whether to conform to the federal government's new Superhuman Registration Act. This knowledge was erased from the world with the event of the four-part, crossover story arc, "One More Day", written partially by J. Michael Straczynski and illustrated by Joe Quesada, running through The Amazing Spider-Man #544–545 (Nov.-Dec. 2007), Friendly Neighborhood Spider-Man No. 24 (Nov. 2007) and The Sensational Spider-Man No. 41 (Dec. 2007), the final issues of those two titles. Here, the demon Mephisto makes a Faustian bargain with Parker and Mary Jane, offering to save Parker's dying Aunt May if the couple will allow their marriage to have never existed, rewriting that portion of their pasts. This story arc marked the end of Straczynski's work on the title. Following this, Marvel made The Amazing Spider-Man the company's sole Spider-Man title, increasing its frequency of publication to three issues monthly, and inaugurating the series with a sequence of "back to basics" story arcs under the banner of "Brand New Day". Parker now exists in a changed world where he and Mary Jane had never married, and Parker has no memory of being married to her, with domino effect differences in their immediate world. The most notable of these revisions to Spider-Man continuity are the return of Harry Osborn, whose death in The Spectacular Spider-Man No.

200 (May 1993) is erased; and the reestablishment of Spider-Man's secret identity, with no one except Mary Jane able to recall that Parker is Spider-Man (although he soon reveals his secret identity to the New Avengers and the Fantastic Four). Under the banner of Brand New Day, Marvel tried to only use newly created villains instead of relying on older ones. Characters like Mister Negative and Overdrive both in Free Comic Book Day 2007 Spider-Man (July 2007), Menace in No. 549 (March 2008), Ana and Sasha Kravinoff in No. 565 (September 2008) and No. 567 (October 2008) respectively, and several more were introduced. The alternating regular writers were initially Dan Slott, Bob Gale, Marc Guggenheim, and Zeb Wells, joined by a rotation of artists that included Steve McNiven, Salvador Larroca, Phil Jimenez, Barry Kitson, Chris Bachalo, Mike McKone, Marcos Martín, and John Romita Jr. Joe Kelly, Mark Waid, Fred Van Lente and Roger Stern later joined the writing team and Paolo Rivera, Lee Weeks and Marco Checchetto the artist roster. Waid's work on the series included a meeting between Spider-Man and Stephen Colbert in The Amazing Spider-Man No. 573 (Dec. 2008). Issue No. 583 (March 2009) included a back-up story in which Spider-Man meets President Barack Obama. 2010s and temporary end of publication Mark Waid scripted the opening of "The Gauntlet" storyline in issue No. 612 (Jan. 2010). The Gauntlet story was concluded by Grim Hunt (No. 634-637) which saw the resurrection of long-dead Spider-Man villain, Kraven the Hunter. The series became a twice-monthly title with Dan Slott as sole writer at issue No. 648 (Jan. 2011), launching the Big Time storyline. Eight additional pages were added per issue. Big Time saw major changes in Spider-Man/Peter Parker's life, Peter would start working at Horizon Labs and begin a relationship with Carlie Cooper (his first serious relationship since his marriage to Mary Jane), Mac Gargan returned as Scorpion after spending the past few years as Venom, Phil Urich would take up the mantle of Hobgoblin, and the death of J. Jonah Jameson's wife, Marla Jameson. Issues 654 and 654.1 saw the birth of Agent Venom, Flash Thompson bonded with the Venom symbiote, which would lead to Venom getting his own series Venom (volume 2). Starting in No. 659 and going to No. 655, the series built-up to the Spider-Island event which officially started in No. 666 and ended in No. 673. Ends of the Earth was the next event that ran from No. 682 through No. 687. This publishing format lasted until issue No. 700, which concluded the "Dying Wish" storyline, in which Parker and Doctor Octopus swapped bodies, and the latter taking on the mantle of Spider-Man when Parker apparently died in Doctor Octopus' body. The Amazing Spider-Man ended with this issue, with the story continuing in the new series The Superior Spider-Man.

200 (May 1993) is erased; and the reestablishment of Spider-Man's secret identity, with no one except Mary Jane able to recall that Parker is Spider-Man (although he soon reveals his secret identity to the New Avengers and the Fantastic Four). Under the banner of Brand New Day, Marvel tried to only use newly created villains instead of relying on older ones. Characters like Mister Negative and Overdrive both in Free Comic Book Day 2007 Spider-Man (July 2007), Menace in No. 549 (March 2008), Ana and Sasha Kravinoff in No. 565 (September 2008) and No. 567 (October 2008) respectively, and several more were introduced. The alternating regular writers were initially Dan Slott, Bob Gale, Marc Guggenheim, and Zeb Wells, joined by a rotation of artists that included Steve McNiven, Salvador Larroca, Phil Jimenez, Barry Kitson, Chris Bachalo, Mike McKone, Marcos Martín, and John Romita Jr. Joe Kelly, Mark Waid, Fred Van Lente and Roger Stern later joined the writing team and Paolo Rivera, Lee Weeks and Marco Checchetto the artist roster. Waid's work on the series included a meeting between Spider-Man and Stephen Colbert in The Amazing Spider-Man No. 573 (Dec. 2008). Issue No. 583 (March 2009) included a back-up story in which Spider-Man meets President Barack Obama. 2010s and temporary end of publication Mark Waid scripted the opening of "The Gauntlet" storyline in issue No. 612 (Jan. 2010). The Gauntlet story was concluded by Grim Hunt (No. 634-637) which saw the resurrection of long-dead Spider-Man villain, Kraven the Hunter. The series became a twice-monthly title with Dan Slott as sole writer at issue No. 648 (Jan. 2011), launching the Big Time storyline. Eight additional pages were added per issue. Big Time saw major changes in Spider-Man/Peter Parker's life, Peter would start working at Horizon Labs and begin a relationship with Carlie Cooper (his first serious relationship since his marriage to Mary Jane), Mac Gargan returned as Scorpion after spending the past few years as Venom, Phil Urich would take up the mantle of Hobgoblin, and the death of J. Jonah Jameson's wife, Marla Jameson. Issues 654 and 654.1 saw the birth of Agent Venom, Flash Thompson bonded with the Venom symbiote, which would lead to Venom getting his own series Venom (volume 2). Starting in No. 659 and going to No. 655, the series built-up to the Spider-Island event which officially started in No. 666 and ended in No. 673. Ends of the Earth was the next event that ran from No. 682 through No. 687. This publishing format lasted until issue No. 700, which concluded the "Dying Wish" storyline, in which Parker and Doctor Octopus swapped bodies, and the latter taking on the mantle of Spider-Man when Parker apparently died in Doctor Octopus' body. The Amazing Spider-Man ended with this issue, with the story continuing in the new series The Superior Spider-Man.

200 (May 1993) is erased; and the reestablishment of Spider-Man's secret identity, with no one except Mary Jane able to recall that Parker is Spider-Man (although he soon reveals his secret identity to the New Avengers and the Fantastic Four). Under the banner of Brand New Day, Marvel tried to only use newly created villains instead of relying on older ones. Characters like Mister Negative and Overdrive both in Free Comic Book Day 2007 Spider-Man (July 2007), Menace in No. 549 (March 2008), Ana and Sasha Kravinoff in No. 565 (September 2008) and No. 567 (October 2008) respectively, and several more were introduced. The alternating regular writers were initially Dan Slott, Bob Gale, Marc Guggenheim, and Zeb Wells, joined by a rotation of artists that included Steve McNiven, Salvador Larroca, Phil Jimenez, Barry Kitson, Chris Bachalo, Mike McKone, Marcos Martín, and John Romita Jr. Joe Kelly, Mark Waid, Fred Van Lente and Roger Stern later joined the writing team and Paolo Rivera, Lee Weeks and Marco Checchetto the artist roster. Waid's work on the series included a meeting between Spider-Man and Stephen Colbert in The Amazing Spider-Man No. 573 (Dec. 2008). Issue No. 583 (March 2009) included a back-up story in which Spider-Man meets President Barack Obama. 2010s and temporary end of publication Mark Waid scripted the opening of "The Gauntlet" storyline in issue No. 612 (Jan. 2010). The Gauntlet story was concluded by Grim Hunt (No. 634-637) which saw the resurrection of long-dead Spider-Man villain, Kraven the Hunter. The series became a twice-monthly title with Dan Slott as sole writer at issue No. 648 (Jan. 2011), launching the Big Time storyline. Eight additional pages were added per issue. Big Time saw major changes in Spider-Man/Peter Parker's life, Peter would start working at Horizon Labs and begin a relationship with Carlie Cooper (his first serious relationship since his marriage to Mary Jane), Mac Gargan returned as Scorpion after spending the past few years as Venom, Phil Urich would take up the mantle of Hobgoblin, and the death of J. Jonah Jameson's wife, Marla Jameson. Issues 654 and 654.1 saw the birth of Agent Venom, Flash Thompson bonded with the Venom symbiote, which would lead to Venom getting his own series Venom (volume 2). Starting in No. 659 and going to No. 655, the series built-up to the Spider-Island event which officially started in No. 666 and ended in No. 673. Ends of the Earth was the next event that ran from No. 682 through No. 687. This publishing format lasted until issue No. 700, which concluded the "Dying Wish" storyline, in which Parker and Doctor Octopus swapped bodies, and the latter taking on the mantle of Spider-Man when Parker apparently died in Doctor Octopus' body. The Amazing Spider-Man ended with this issue, with the story continuing in the new series The Superior Spider-Man.

Despite The Superior Spider-Man being considered a different series to The Amazing Spider-Man, the first 33 issue run goes towards the legacy numbering of The Amazing Spider-Man acting as issues 701–733. In December 2013, the series returned for five issues, numbered 700.1 through 700.5, with the first two written by David Morrell and drawn by Klaus Janson. 2014 relaunch In January 2014, Marvel confirmed that The Amazing Spider-Man would be relaunched on April 30, 2014, starting from issue No. 1, with Peter Parker as Spider-Man once again. The first issue of this new version of The Amazing Spider-Man was, according to Diamond Comics Distributors, the "best-selling comic book... in over a decade." Issues #1–6 were a story arc called "Lucky to be Alive", taking place immediately after "Goblin Nation", with issues No. 4 and No. 5 being a crossover with the Original Sin storyline. Issue No. 4 introduced Silk, a new heroine who was bitten by the same spider as Peter Parker. Issues #7–8 featured a team-up between Ms. Marvel and Spider-Man, and had backup stories that tied into "Edge of Spider-Verse". The next major plot arc, titled "Spider-Verse", began in Issue No. 9 and ended in No. 15, features every Spider-Man from across the dimensions being hunted by Morlun, and a team-up to stop him, with Peter Parker of Earth-616 in command of the Spider-Men's Alliance. The Amazing Spider-Man Annual No. 1 of the relaunched series was released in December 2014, featuring stories unrelated to "Spider-Verse". The Amazing Spider-Man: Renew Your Vows In 2015, Marvel started the universe wide Secret Wars event where the core and several other Marvel universes were combined into one big planet called Battleworld. Battleworld was divided into sections with most of them being self-contained universes. Marvel announced that several of these self-contained universes would get their own tie in series and one of them was Amazing Spider-Man: Renew Your Vows, an alternate universe where Peter Parker and Mary Jane are still married and give birth to their child Annie May Parker, written by Dan Slott. Despite the series being considered separate from the main Amazing Spider-Man series, the original 5 issue run is counted towards its legacy numbering acting as No. 752-756. 2015 relaunch Following the 2015 Secret Wars event, a number of Spider-Man-related titles were either relaunched or created as part of the "All-New, All-Different Marvel" event. Among them, The Amazing Spider-Man was relaunched as well and primarily focuses on Peter Parker continuing to run Parker Industries, and becoming a successful businessman who is operating worldwide. It also tied with Civil War II (involving an Inhuman who can predict possible future named Ulysses Cain), Dead No More (where Ben Reilly [the original Scarlet Spider] revealed to be revived and as one of the antagonists instead), and Secret Empire (during Hydra's reign led by a Hydra influenced Captain America/Steve Rogers, and the dismissal of Parker Industries by Peter Parker to stop Otto Octavius).

Despite The Superior Spider-Man being considered a different series to The Amazing Spider-Man, the first 33 issue run goes towards the legacy numbering of The Amazing Spider-Man acting as issues 701–733. In December 2013, the series returned for five issues, numbered 700.1 through 700.5, with the first two written by David Morrell and drawn by Klaus Janson. 2014 relaunch In January 2014, Marvel confirmed that The Amazing Spider-Man would be relaunched on April 30, 2014, starting from issue No. 1, with Peter Parker as Spider-Man once again. The first issue of this new version of The Amazing Spider-Man was, according to Diamond Comics Distributors, the "best-selling comic book... in over a decade." Issues #1–6 were a story arc called "Lucky to be Alive", taking place immediately after "Goblin Nation", with issues No. 4 and No. 5 being a crossover with the Original Sin storyline. Issue No. 4 introduced Silk, a new heroine who was bitten by the same spider as Peter Parker. Issues #7–8 featured a team-up between Ms. Marvel and Spider-Man, and had backup stories that tied into "Edge of Spider-Verse". The next major plot arc, titled "Spider-Verse", began in Issue No. 9 and ended in No. 15, features every Spider-Man from across the dimensions being hunted by Morlun, and a team-up to stop him, with Peter Parker of Earth-616 in command of the Spider-Men's Alliance. The Amazing Spider-Man Annual No. 1 of the relaunched series was released in December 2014, featuring stories unrelated to "Spider-Verse". The Amazing Spider-Man: Renew Your Vows In 2015, Marvel started the universe wide Secret Wars event where the core and several other Marvel universes were combined into one big planet called Battleworld. Battleworld was divided into sections with most of them being self-contained universes. Marvel announced that several of these self-contained universes would get their own tie in series and one of them was Amazing Spider-Man: Renew Your Vows, an alternate universe where Peter Parker and Mary Jane are still married and give birth to their child Annie May Parker, written by Dan Slott. Despite the series being considered separate from the main Amazing Spider-Man series, the original 5 issue run is counted towards its legacy numbering acting as No. 752-756. 2015 relaunch Following the 2015 Secret Wars event, a number of Spider-Man-related titles were either relaunched or created as part of the "All-New, All-Different Marvel" event. Among them, The Amazing Spider-Man was relaunched as well and primarily focuses on Peter Parker continuing to run Parker Industries, and becoming a successful businessman who is operating worldwide. It also tied with Civil War II (involving an Inhuman who can predict possible future named Ulysses Cain), Dead No More (where Ben Reilly [the original Scarlet Spider] revealed to be revived and as one of the antagonists instead), and Secret Empire (during Hydra's reign led by a Hydra influenced Captain America/Steve Rogers, and the dismissal of Parker Industries by Peter Parker to stop Otto Octavius).

Despite The Superior Spider-Man being considered a different series to The Amazing Spider-Man, the first 33 issue run goes towards the legacy numbering of The Amazing Spider-Man acting as issues 701–733. In December 2013, the series returned for five issues, numbered 700.1 through 700.5, with the first two written by David Morrell and drawn by Klaus Janson. 2014 relaunch In January 2014, Marvel confirmed that The Amazing Spider-Man would be relaunched on April 30, 2014, starting from issue No. 1, with Peter Parker as Spider-Man once again. The first issue of this new version of The Amazing Spider-Man was, according to Diamond Comics Distributors, the "best-selling comic book... in over a decade." Issues #1–6 were a story arc called "Lucky to be Alive", taking place immediately after "Goblin Nation", with issues No. 4 and No. 5 being a crossover with the Original Sin storyline. Issue No. 4 introduced Silk, a new heroine who was bitten by the same spider as Peter Parker. Issues #7–8 featured a team-up between Ms. Marvel and Spider-Man, and had backup stories that tied into "Edge of Spider-Verse". The next major plot arc, titled "Spider-Verse", began in Issue No. 9 and ended in No. 15, features every Spider-Man from across the dimensions being hunted by Morlun, and a team-up to stop him, with Peter Parker of Earth-616 in command of the Spider-Men's Alliance. The Amazing Spider-Man Annual No. 1 of the relaunched series was released in December 2014, featuring stories unrelated to "Spider-Verse". The Amazing Spider-Man: Renew Your Vows In 2015, Marvel started the universe wide Secret Wars event where the core and several other Marvel universes were combined into one big planet called Battleworld. Battleworld was divided into sections with most of them being self-contained universes. Marvel announced that several of these self-contained universes would get their own tie in series and one of them was Amazing Spider-Man: Renew Your Vows, an alternate universe where Peter Parker and Mary Jane are still married and give birth to their child Annie May Parker, written by Dan Slott. Despite the series being considered separate from the main Amazing Spider-Man series, the original 5 issue run is counted towards its legacy numbering acting as No. 752-756. 2015 relaunch Following the 2015 Secret Wars event, a number of Spider-Man-related titles were either relaunched or created as part of the "All-New, All-Different Marvel" event. Among them, The Amazing Spider-Man was relaunched as well and primarily focuses on Peter Parker continuing to run Parker Industries, and becoming a successful businessman who is operating worldwide. It also tied with Civil War II (involving an Inhuman who can predict possible future named Ulysses Cain), Dead No More (where Ben Reilly [the original Scarlet Spider] revealed to be revived and as one of the antagonists instead), and Secret Empire (during Hydra's reign led by a Hydra influenced Captain America/Steve Rogers, and the dismissal of Parker Industries by Peter Parker to stop Otto Octavius).

Starting in September 2017, Marvel started the Marvel Legacy event which renumbered several Marvel series to their original numbering, The Amazing Spider-Man was put back to its original numbering for issue 789. Issues 789 through 791 focused on the aftermath of Peter destroying Parker Industries and his fall from grace. Issues 792 and 793 were part of the Venom Inc. story. Threat Level: Red was the story for the next three issues which saw Norman Osborn obtain and bond with the Carnage symbiote. Go Down Swinging saw the results of the combination of Osborn's goblin serum and Carnage symbiote creating the Red Goblin. Issue 801 was Dan Slott's goodbye issue. 2018 relaunch In March 2018, it was announced that writer Nick Spencer would be writing the main bi-monthly The Amazing Spider-Man series beginning with a new No. 1, replacing long-time writer Dan Slott, as part of the Fresh Start relaunch that July. The first five-issue story arc was titled 'Back to Basics.' During the Back to Basics story, Kindred, a mysterious villain with some relation to Peter's past, was introduced. The first major story under Spencer was Hunted which ran through issues 16 through 23, the story also included four ".HU" issues for issues 16, 18, 19, and 20. The end of the story saw the death of long-running Spider-Man villain Kraven the Hunter, being replaced by his clone son, The Last Son of Kraven. 2020s Issue 45 kicked off the Sins Rising story which saw the resurrected Sin-Eater carry out the plans of Kindred to cleanse the world of sin, particularly that of Norman Osborn. The story concluded with issue 49, issue 850 in legacy numbering, seeing Spider-Man and Green Goblin team up to defeat Sin-Eater. Last Remains started in issue 50 and concluded in issue 55, the story saw Kindred's plans come to fruition as he tormented Spider-Man. The story has also saw five ".LR" for issues 50, 51, 52, 53, and 54 which focused on The Order of the Web, a new faction of Spider-People consisting of Julia Carpenter (Madame Web), Miles Morales (Spider-Man), Gwen Stacy (Ghost-Spider), Cindy Moon (Silk), Jessica Drew (Spider-Woman), and Anya Corazon (Spider-Girl) . The story also revealed that Kindred is Harry Osborn. Last Remains also received two fallout issues called Last Remains Post-Mortem. Nick Spencer concluded his run with the Sinister War story which wrapped up in Np. 74 (legacy numbering 875). The story saw several retcons to the Spider-Man mythos including that Kindred was Gabriel and Sarah Stacy all along, the fact that the Stacy twins were actually genetically engineered beings using Norman Osborn and Gwen Stacy's DNA, that the Harry Osborn that returned in Brand New Day was actually a clone, and that Norman had made a deal with Mephisto where he sold Harry's soul to the demon. The story ended with the deaths of the Harry clone, Gabriel, and Sarah and the real Harry's soul being freed from Mephisto's grasp.

Starting in September 2017, Marvel started the Marvel Legacy event which renumbered several Marvel series to their original numbering, The Amazing Spider-Man was put back to its original numbering for issue 789. Issues 789 through 791 focused on the aftermath of Peter destroying Parker Industries and his fall from grace. Issues 792 and 793 were part of the Venom Inc. story. Threat Level: Red was the story for the next three issues which saw Norman Osborn obtain and bond with the Carnage symbiote. Go Down Swinging saw the results of the combination of Osborn's goblin serum and Carnage symbiote creating the Red Goblin. Issue 801 was Dan Slott's goodbye issue. 2018 relaunch In March 2018, it was announced that writer Nick Spencer would be writing the main bi-monthly The Amazing Spider-Man series beginning with a new No. 1, replacing long-time writer Dan Slott, as part of the Fresh Start relaunch that July. The first five-issue story arc was titled 'Back to Basics.' During the Back to Basics story, Kindred, a mysterious villain with some relation to Peter's past, was introduced. The first major story under Spencer was Hunted which ran through issues 16 through 23, the story also included four ".HU" issues for issues 16, 18, 19, and 20. The end of the story saw the death of long-running Spider-Man villain Kraven the Hunter, being replaced by his clone son, The Last Son of Kraven. 2020s Issue 45 kicked off the Sins Rising story which saw the resurrected Sin-Eater carry out the plans of Kindred to cleanse the world of sin, particularly that of Norman Osborn. The story concluded with issue 49, issue 850 in legacy numbering, seeing Spider-Man and Green Goblin team up to defeat Sin-Eater. Last Remains started in issue 50 and concluded in issue 55, the story saw Kindred's plans come to fruition as he tormented Spider-Man. The story has also saw five ".LR" for issues 50, 51, 52, 53, and 54 which focused on The Order of the Web, a new faction of Spider-People consisting of Julia Carpenter (Madame Web), Miles Morales (Spider-Man), Gwen Stacy (Ghost-Spider), Cindy Moon (Silk), Jessica Drew (Spider-Woman), and Anya Corazon (Spider-Girl) . The story also revealed that Kindred is Harry Osborn. Last Remains also received two fallout issues called Last Remains Post-Mortem. Nick Spencer concluded his run with the Sinister War story which wrapped up in Np. 74 (legacy numbering 875). The story saw several retcons to the Spider-Man mythos including that Kindred was Gabriel and Sarah Stacy all along, the fact that the Stacy twins were actually genetically engineered beings using Norman Osborn and Gwen Stacy's DNA, that the Harry Osborn that returned in Brand New Day was actually a clone, and that Norman had made a deal with Mephisto where he sold Harry's soul to the demon. The story ended with the deaths of the Harry clone, Gabriel, and Sarah and the real Harry's soul being freed from Mephisto's grasp.

Starting in September 2017, Marvel started the Marvel Legacy event which renumbered several Marvel series to their original numbering, The Amazing Spider-Man was put back to its original numbering for issue 789. Issues 789 through 791 focused on the aftermath of Peter destroying Parker Industries and his fall from grace. Issues 792 and 793 were part of the Venom Inc. story. Threat Level: Red was the story for the next three issues which saw Norman Osborn obtain and bond with the Carnage symbiote. Go Down Swinging saw the results of the combination of Osborn's goblin serum and Carnage symbiote creating the Red Goblin. Issue 801 was Dan Slott's goodbye issue. 2018 relaunch In March 2018, it was announced that writer Nick Spencer would be writing the main bi-monthly The Amazing Spider-Man series beginning with a new No. 1, replacing long-time writer Dan Slott, as part of the Fresh Start relaunch that July. The first five-issue story arc was titled 'Back to Basics.' During the Back to Basics story, Kindred, a mysterious villain with some relation to Peter's past, was introduced. The first major story under Spencer was Hunted which ran through issues 16 through 23, the story also included four ".HU" issues for issues 16, 18, 19, and 20. The end of the story saw the death of long-running Spider-Man villain Kraven the Hunter, being replaced by his clone son, The Last Son of Kraven. 2020s Issue 45 kicked off the Sins Rising story which saw the resurrected Sin-Eater carry out the plans of Kindred to cleanse the world of sin, particularly that of Norman Osborn. The story concluded with issue 49, issue 850 in legacy numbering, seeing Spider-Man and Green Goblin team up to defeat Sin-Eater. Last Remains started in issue 50 and concluded in issue 55, the story saw Kindred's plans come to fruition as he tormented Spider-Man. The story has also saw five ".LR" for issues 50, 51, 52, 53, and 54 which focused on The Order of the Web, a new faction of Spider-People consisting of Julia Carpenter (Madame Web), Miles Morales (Spider-Man), Gwen Stacy (Ghost-Spider), Cindy Moon (Silk), Jessica Drew (Spider-Woman), and Anya Corazon (Spider-Girl) . The story also revealed that Kindred is Harry Osborn. Last Remains also received two fallout issues called Last Remains Post-Mortem. Nick Spencer concluded his run with the Sinister War story which wrapped up in Np. 74 (legacy numbering 875). The story saw several retcons to the Spider-Man mythos including that Kindred was Gabriel and Sarah Stacy all along, the fact that the Stacy twins were actually genetically engineered beings using Norman Osborn and Gwen Stacy's DNA, that the Harry Osborn that returned in Brand New Day was actually a clone, and that Norman had made a deal with Mephisto where he sold Harry's soul to the demon. The story ended with the deaths of the Harry clone, Gabriel, and Sarah and the real Harry's soul being freed from Mephisto's grasp.

After Spencer left the book, Marvel announced the "Beyond" era of Spider-Man which would start in No. 75. The book would be moving back to the format it had during Brand New Day where the it would have a rotating cast of writers including Kelly Thompson, Saladin Ahmed, Cody Ziglar, Patrick Gleason, and Zeb Wells. The book would also release three times a month. Beyond would focus on Ben Reilly taking up the mantle of Spider-Man once again, but backed by the Beyond corporation. Peter also falls ill and cannot be Spider-Man so he gives Ben his blessing to carry on as the main Spider-Man. Collected editions Black-and-white Essential Spider-Man Vol. 1 [#1–20, Annual #1; Amazing Fantasy #15] () Essential Spider-Man Vol. 2 [#21–43, Annual #2–3] () Essential Spider-Man Vol. 3 [#44–65, Annual #4] () Essential Spider-Man Vol. 4 [#66–89, Annual #5] () Essential Spider-Man Vol. 5 [#90–113] () Essential Spider-Man Vol. 6 [#114–137; Giant-Size Super Heroes #1; Giant-Size Spider-Man #1–2] () Essential Spider-Man Vol. 7 [#138–160, Annual #10; Giant-Size Spider-Man #4–5] () Essential Spider-Man Vol. 8 [#161–185, Annual #11; Giant-Size Spider-Man #6; Nova #12] () Essential Spider-Man Vol. 9 [#186–210, Annual #13–14; Peter Parker: Spectacular Spider-Man Annual #1] () Essential Spider-Man Vol. 10 [#211–230, Annual #15] () Essential Spider-Man Vol. 11 [#231–248, Annual #16–17] () Major story arcs/artist runs Marvel Visionaries: John Romita Sr. [#39–40, 42, 50, 108–109, 365; Daredevil #16–17; Untold Tales of Spider-Man #-1] () Spider-Man: The Death of Captain Stacy [#88–90] () Spider-Man: The Death of Gwen Stacy [#96–98, 121–122; Webspinners: Tales of Spider-Man #1] () Spider-Man: Death of the Stacys [#88–92, 121–122] () A New Goblin [#176–180] () Spider-Man vs. the Black Cat [#194–195, 204–205, 226–227] () Spider-Man: Origin of The Hobgoblin [#238–239, 244–245, 249–251, Spectacular Spider-Man (vol. 1) #85] () Spider-Man: Birth of Venom [#252–259, 298–300, 315–317, Annual #25; Fantastic Four #274; Secret Wars #8; Web of Spider-Man #1] () The Amazing Spider-Man: The Wedding [#290–292, Annual #2, Not Brand Echh #6] () Spider-Man: Kraven's Last Hunt [#293–294; Web of Spider-Man #31–32; The Spectacular Spider-Man #131–132] () Visionaries: Todd McFarlane [#298–305] () Legends, Vol. 2: Todd McFarlane [#306–314; The Spectacular Spider-Man Annual #10] () Legends, Vol. 3: Todd McFarlane [#315–323, 325, 328] () Spider-Man: Venom Returns [#330–333, 344–347;Annual #25] () Spider-Man: Carnage [#344–345, 359–363] () Collections Vol. 1: Coming Home [#30-35/471-476] () Vol. 2: Revelations [#36-39/477-480] () Vol. 3: Until the Stars Turn Cold [#40-45/481-486] () Vol. 4: The Life and Death of Spiders [#46-50/487-491] () Vol. 5: Unintended Consequences [#51-56/492-497] () Vol. 6: Happy Birthday [#57–58,500-502/498-502] () Vol. 7: The Book of Ezekiel [#503–508] () Vol. 8: Sins Past [#509–514] () Vol. 9: Skin Deep [#515–518] () Vol. 10: New Avengers [#519–524] () Spider-Man: The Other [#525–528; Friendly Neighborhood Spider-Man #1–4; Marvel Knights Spider-Man #19–22] () Civil War: The Road to Civil War [#529–531; New Avengers: Illuminati (one-shot); Fantastic Four #536–537] () Vol. 11: Civil War [#532–538] () Vol.

After Spencer left the book, Marvel announced the "Beyond" era of Spider-Man which would start in No. 75. The book would be moving back to the format it had during Brand New Day where the it would have a rotating cast of writers including Kelly Thompson, Saladin Ahmed, Cody Ziglar, Patrick Gleason, and Zeb Wells. The book would also release three times a month. Beyond would focus on Ben Reilly taking up the mantle of Spider-Man once again, but backed by the Beyond corporation. Peter also falls ill and cannot be Spider-Man so he gives Ben his blessing to carry on as the main Spider-Man. Collected editions Black-and-white Essential Spider-Man Vol. 1 [#1–20, Annual #1; Amazing Fantasy #15] () Essential Spider-Man Vol. 2 [#21–43, Annual #2–3] () Essential Spider-Man Vol. 3 [#44–65, Annual #4] () Essential Spider-Man Vol. 4 [#66–89, Annual #5] () Essential Spider-Man Vol. 5 [#90–113] () Essential Spider-Man Vol. 6 [#114–137; Giant-Size Super Heroes #1; Giant-Size Spider-Man #1–2] () Essential Spider-Man Vol. 7 [#138–160, Annual #10; Giant-Size Spider-Man #4–5] () Essential Spider-Man Vol. 8 [#161–185, Annual #11; Giant-Size Spider-Man #6; Nova #12] () Essential Spider-Man Vol. 9 [#186–210, Annual #13–14; Peter Parker: Spectacular Spider-Man Annual #1] () Essential Spider-Man Vol. 10 [#211–230, Annual #15] () Essential Spider-Man Vol. 11 [#231–248, Annual #16–17] () Major story arcs/artist runs Marvel Visionaries: John Romita Sr. [#39–40, 42, 50, 108–109, 365; Daredevil #16–17; Untold Tales of Spider-Man #-1] () Spider-Man: The Death of Captain Stacy [#88–90] () Spider-Man: The Death of Gwen Stacy [#96–98, 121–122; Webspinners: Tales of Spider-Man #1] () Spider-Man: Death of the Stacys [#88–92, 121–122] () A New Goblin [#176–180] () Spider-Man vs. the Black Cat [#194–195, 204–205, 226–227] () Spider-Man: Origin of The Hobgoblin [#238–239, 244–245, 249–251, Spectacular Spider-Man (vol. 1) #85] () Spider-Man: Birth of Venom [#252–259, 298–300, 315–317, Annual #25; Fantastic Four #274; Secret Wars #8; Web of Spider-Man #1] () The Amazing Spider-Man: The Wedding [#290–292, Annual #2, Not Brand Echh #6] () Spider-Man: Kraven's Last Hunt [#293–294; Web of Spider-Man #31–32; The Spectacular Spider-Man #131–132] () Visionaries: Todd McFarlane [#298–305] () Legends, Vol. 2: Todd McFarlane [#306–314; The Spectacular Spider-Man Annual #10] () Legends, Vol. 3: Todd McFarlane [#315–323, 325, 328] () Spider-Man: Venom Returns [#330–333, 344–347;Annual #25] () Spider-Man: Carnage [#344–345, 359–363] () Collections Vol. 1: Coming Home [#30-35/471-476] () Vol. 2: Revelations [#36-39/477-480] () Vol. 3: Until the Stars Turn Cold [#40-45/481-486] () Vol. 4: The Life and Death of Spiders [#46-50/487-491] () Vol. 5: Unintended Consequences [#51-56/492-497] () Vol. 6: Happy Birthday [#57–58,500-502/498-502] () Vol. 7: The Book of Ezekiel [#503–508] () Vol. 8: Sins Past [#509–514] () Vol. 9: Skin Deep [#515–518] () Vol. 10: New Avengers [#519–524] () Spider-Man: The Other [#525–528; Friendly Neighborhood Spider-Man #1–4; Marvel Knights Spider-Man #19–22] () Civil War: The Road to Civil War [#529–531; New Avengers: Illuminati (one-shot); Fantastic Four #536–537] () Vol. 11: Civil War [#532–538] () Vol.

After Spencer left the book, Marvel announced the "Beyond" era of Spider-Man which would start in No. 75. The book would be moving back to the format it had during Brand New Day where the it would have a rotating cast of writers including Kelly Thompson, Saladin Ahmed, Cody Ziglar, Patrick Gleason, and Zeb Wells. The book would also release three times a month. Beyond would focus on Ben Reilly taking up the mantle of Spider-Man once again, but backed by the Beyond corporation. Peter also falls ill and cannot be Spider-Man so he gives Ben his blessing to carry on as the main Spider-Man. Collected editions Black-and-white Essential Spider-Man Vol. 1 [#1–20, Annual #1; Amazing Fantasy #15] () Essential Spider-Man Vol. 2 [#21–43, Annual #2–3] () Essential Spider-Man Vol. 3 [#44–65, Annual #4] () Essential Spider-Man Vol. 4 [#66–89, Annual #5] () Essential Spider-Man Vol. 5 [#90–113] () Essential Spider-Man Vol. 6 [#114–137; Giant-Size Super Heroes #1; Giant-Size Spider-Man #1–2] () Essential Spider-Man Vol. 7 [#138–160, Annual #10; Giant-Size Spider-Man #4–5] () Essential Spider-Man Vol. 8 [#161–185, Annual #11; Giant-Size Spider-Man #6; Nova #12] () Essential Spider-Man Vol. 9 [#186–210, Annual #13–14; Peter Parker: Spectacular Spider-Man Annual #1] () Essential Spider-Man Vol. 10 [#211–230, Annual #15] () Essential Spider-Man Vol. 11 [#231–248, Annual #16–17] () Major story arcs/artist runs Marvel Visionaries: John Romita Sr. [#39–40, 42, 50, 108–109, 365; Daredevil #16–17; Untold Tales of Spider-Man #-1] () Spider-Man: The Death of Captain Stacy [#88–90] () Spider-Man: The Death of Gwen Stacy [#96–98, 121–122; Webspinners: Tales of Spider-Man #1] () Spider-Man: Death of the Stacys [#88–92, 121–122] () A New Goblin [#176–180] () Spider-Man vs. the Black Cat [#194–195, 204–205, 226–227] () Spider-Man: Origin of The Hobgoblin [#238–239, 244–245, 249–251, Spectacular Spider-Man (vol. 1) #85] () Spider-Man: Birth of Venom [#252–259, 298–300, 315–317, Annual #25; Fantastic Four #274; Secret Wars #8; Web of Spider-Man #1] () The Amazing Spider-Man: The Wedding [#290–292, Annual #2, Not Brand Echh #6] () Spider-Man: Kraven's Last Hunt [#293–294; Web of Spider-Man #31–32; The Spectacular Spider-Man #131–132] () Visionaries: Todd McFarlane [#298–305] () Legends, Vol. 2: Todd McFarlane [#306–314; The Spectacular Spider-Man Annual #10] () Legends, Vol. 3: Todd McFarlane [#315–323, 325, 328] () Spider-Man: Venom Returns [#330–333, 344–347;Annual #25] () Spider-Man: Carnage [#344–345, 359–363] () Collections Vol. 1: Coming Home [#30-35/471-476] () Vol. 2: Revelations [#36-39/477-480] () Vol. 3: Until the Stars Turn Cold [#40-45/481-486] () Vol. 4: The Life and Death of Spiders [#46-50/487-491] () Vol. 5: Unintended Consequences [#51-56/492-497] () Vol. 6: Happy Birthday [#57–58,500-502/498-502] () Vol. 7: The Book of Ezekiel [#503–508] () Vol. 8: Sins Past [#509–514] () Vol. 9: Skin Deep [#515–518] () Vol. 10: New Avengers [#519–524] () Spider-Man: The Other [#525–528; Friendly Neighborhood Spider-Man #1–4; Marvel Knights Spider-Man #19–22] () Civil War: The Road to Civil War [#529–531; New Avengers: Illuminati (one-shot); Fantastic Four #536–537] () Vol. 11: Civil War [#532–538] () Vol.

12: Back in Black [#539–543; Friendly Neighborhood Spider-Man #17–23, Annual #1] () Spider-Man: One More Day [#544–545; Friendly Neighborhood Spider-Man #24; The Sensational Spider-Man #41; Marvel Spotlight: Spider-Man – One More Day/Brand New Day] () Brand New Day Vol. 1 [#546–551; The Amazing Spider-Man: Swing Shift (Director's Cut); Venom Super-Special] () Brand New Day Vol. 2 [#552–558] () Brand New Day Vol. 3 [#559–563] () Kraven's First Hunt [#564–567; The Amazing Spider-Man: Extra! #1 (story #2)] () New Ways to Die [#568–573; Marvel Spotlight: Spider-Man – Brand New Day] () Crime and Punisher [#574–577; The Amazing Spider-Man: Extra! #1 (story #1)] () Death and Dating [#578–583, Annual #35/1] () Election Day [#584–588; The Amazing Spider-Man: Extra! #1 (story #3), 3 (story #1); The Amazing Spider-Man Presidents' Day Special] () 24/7 [#589–594; The Amazing Spider-Man: Extra! #2] () American Son [#595–599; material from The Amazing Spider-Man: Extra! #3] () Died in Your Arms Tonight [#600–601, Annual #36; material from Amazing Spider-Man Family #7] () Red-Headed Stranger [#602–605] () Return of the Black Cat [#606–611; material from Web of Spider-Man (vol. 2) #1] () The Gauntlet Book 1: Electro and Sandman [#612–616; Dark Reign: The List – The Amazing Spider-Man; Web of Spider-Man (vol. 2) #2 (Electro story)] () The Gauntlet Book 2: Rhino and Mysterio [#617–621; Web of Spider-Man (vol. 2) #3–4] () The Gauntlet Book 3: Vulture and Morbius [#622–625; Web of Spider-Man (vol. 2) #2, 5 (Vulture story)] () The Gauntlet Book 4: Juggernaut [#229–230, 626–629] () The Gauntlet Book 5: Lizard [#629–633; Web of Spider-Man (vol. 2) #6] () Spider-Man: Grim Hunt [#634–637; The Amazing Spider-Man: Extra! #3; Spider-Man: Grim Hunt – The Kraven Saga; Web of Spider-Man (vol. 2) #7] () One Moment in Time [#638–641] () Origin of the Species [#642–647; Spider-Man Saga; Web of Spider-Man (vol. 2) #12] () Big Time [#648–651] () Matters of Life and Death [#652–657, 654.1] () Spider-Man: The Fantastic Spider-Man [#658–662] () Spider-Man: The Return Of Anti-Venom [#663–665; Free Comic Book Day 2011: Spider-Man] () Spider-Man: Spider-Island [#666–673; Venom (2011) #6–8, Spider-Island: Deadly Foes; Infested prologues from #659–660 and 662–665] () Spider-Man: Flying Blind [#674–677; Daredevil #8] () Spider-Man: Trouble on the Horizon [#678–681, 679.1] () Spider-Man: Ends of the Earth [#682–687; Amazing Spider-Man: Ends of the Earth #1; Avenging Spider-Man #8] () Spider-Man: Lizard – No Turning Back [#688–691; Untold Tales of Spider-Man #9] () Spider-Man: Danger Zone [#692–697; Avenging Spider-Man #11] () Spider-Man: Dying Wish [#698–700] () The Amazing Spider-Man Omnibus Vol. 1 [#1–38, Annual #1–2; Amazing Fantasy #15; Strange Tales Annual #2; Fantastic Four Annual #1] () The Amazing Spider-Man Omnibus Vol. 2 [#39–67, Annual #3–5; Spectacular Spider-Man #1–2] () Marvel Masterworks: The Amazing Spider-Man Vol. 1 [#1–10; Amazing Fantasy #15] () Marvel Masterworks: The Amazing Spider-Man Vol. 2 [#11–19, Annual #1] () Marvel Masterworks: The Amazing Spider-Man Vol. 3 [#20–30, Annual #2] () Marvel Masterworks: The Amazing Spider-Man Vol. 4 [#31–40] () Marvel Masterworks: The Amazing Spider-Man Vol.