Communication
Communication (from , meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term can also refer just to the message communicated or to the field of inquiry studying such transmissions. There are many disagreements about its precise definition. John Peters argues that the difficulty of defining communication emerges from the fact that communication is both a universal phenomenon (because everyone communicates) and a specific discipline of institutional academic study. One definitional strategy involves limiting what can be included in the category of communication (for example, requiring a "conscious intent" to persuade). By this logic, one possible definition of communication is the act of developing meaning among entities or groups through the use of sufficiently mutually understood signs, symbols, and semiotic conventions.

An important distinction is between verbal communication, which happens through the use of a language, and non-verbal communication, for example, through gestures or facial expressions. Models of communication try to provide a detailed explanation of the different steps and entities involved. An influential model is given by Claude Shannon and Warren Weaver, who argue that communicative motivation prompts the sender to compose a message, which is then encoded and transmitted. Once it has reached its destination, it is decoded and interpreted by the receiver.Fiske, John (1982): Introduction to Communication Studies. London: RoutledgeShannon, Claude E. & Warren Weaver (1949). A Mathematical Model of Communication. Urbana, IL: University of Illinois Press Communication is studied in various fields. Information theory investigates the quantification, storage, and communication of information in general. Communication studies is concerned with human communication, while the science of biocommunication is interested in any form of communication between living organisms.

Communication can be realized visually (through images and written language) and through auditory, tactile/haptic (e.g. Braille or other physical means), olfactory, electromagnetic, or biochemical means (or any combination thereof). Human communication is unique in its extensive use of abstract language.

 Definitions 
Communication is usually understood as the transmission of information. In this regard, a message is conveyed from a sender to a receiver using some form of medium, such as sound, paper, bodily movements, or electricity. In a different sense, the term "communication" can also refer just to the message that is being communicated or to the field of inquiry studying such transmissions. There is a lot of disagreement concerning the precise characterization of communication and various scholars have raised doubts that any single definition can capture the term accurately. These difficulties come from the fact that the term is applied to diverse phenomena in different contexts, often with slightly different meanings. Despite these problems, the question of the right definition is of great theoretical importance since it affects the research process on all levels. This includes issues like which empirical phenomena are observed, how they are categorized, which hypotheses and laws are formulated as well as how systematic theories based on these steps are articulated. The word "communication" has its root in the Latin verb "communicare", which means "to share" or "to make common".

Some theorists give very broad definitions of communication that encompass unconscious and non-human behavior. In this regard, many animals communicate within their own species and even plants like flowers may be said to communicate by attracting bees. Other researchers restrict communication to conscious interactions among human beings. Some definitions focus on the use of symbols and signs while others emphasize the role of understanding, interaction, power, or transmission of ideas. Various characterizations see the communicator's intent to send a message as a central component. On this view, the transmission of information is not sufficient for communication if it happens unintentionally. An important version of this view is given by Paul Grice, who identifies communication with actions that aim to make the recipient aware of the communicator's intention. One question in this regard is whether only the successful transmission of information should be regarded as communication. For example, distortion may interfere and change the actual message from what was originally intended. A closely related problem is whether acts of deliberate deception constitute communication. 

According to an influential and broad definition by I. A. Richards, communication happens when one mind acts upon its environment in order to transmit its own experience to another mind. Another important characterization is due to Claude Shannon and Warren Weaver. On their view, communication involves the interaction of several components, such as a source, a message, an encoder, a channel, a decoder, and a receiver. The paradigmatic form of communication happens between two or several individuals. However, it can also take place on a larger level, for example, between organizations, social classes, or nations. Niklas Luhmann rejects the view that communication is, on its most fundamental level, an interaction between two distinct parties. Instead, he holds that "only communication can communicate" and tries to provide a conceptualization in terms of autopoietic systems without any reference to consciousness or life. John Peters sees communication as "an apparent answer to the painful divisions between self and other, private and public, and inner thought and outer world."

Types
Verbal communication

Verbal communication is the spoken or written conveyance of a message. Human language can be defined as a system of symbols (also known as lexemes) and the grammars (rules) by which the symbols are manipulated. The word "language" also refers to common properties of languages. Language learning normally occurs most intensively during human childhood. Most of the large number of human languages use patterns of sound or gesture for symbols which enable communication with others around them. Languages tend to share certain properties, although there are exceptions. Constructed languages such as Esperanto, programming languages, and various mathematical formalisms are not necessarily restricted to the properties shared by human languages.

Communicators' diverse efforts to produce and interpret meaning in language are functionally constrained by that language's prototypical phonology (sounds that typically appear in a language), morphology (what counts as a word), syntax (word-order), semantics (conventional meaning of words), and pragmatics (which meanings are conventional to which contexts).

The meanings that are attached to words can be literal, or otherwise known as denotative; relating to the topic being discussed, or, the meanings take context and relationships into account, otherwise known as connotative; relating to the feelings, history, and power dynamics of the communicators.

Contrary to popular belief, signed languages of the world (e.g., American Sign Language) are considered to be verbal communication because their sign vocabulary, grammar, and other linguistic structures abide by all the necessary classifications as spoken languages. There are however, nonverbal elements to signed languages, such as the speed, intensity, and size of signs that are made. A signer might sign "yes" in response to a question, or they might sign a sarcastic-large slow yes to convey a different nonverbal meaning. The sign yes is the verbal message while the other movements add nonverbal meaning to the message.

Written form
Over time the forms of and ideas about communication have evolved through the continuing progression of technology. Advances include communications psychology and media psychology, an emerging field of study.

The progression of written communication can be divided into three "information communication revolutions":

 Written communication first emerged through the use of pictographs. The pictograms were made in stone, hence written communication was not yet mobile. Pictograms began to develop standardized and simplified forms.
 The next step occurred when writing began to appear on paper, papyrus, clay, wax, and other media with commonly shared writing systems. Communication became mobile.
 The final stage is characterized by the transfer of information through controlled waves of electromagnetic radiation (i.e., radio, microwave, infrared) and other electronic signals.

Communication is thus a process by which meaning is assigned and conveyed in an attempt to create shared understanding. Gregory Bateson called it "the replication of tautologies in the universe.Bateson, Gregory (1960). Steps to an Ecology of Mind. This process, which requires a vast repertoire of skills in interpersonal processing, listening, observing, speaking, questioning, analyzing, gestures, and evaluating enables collaboration and cooperation.

Non-verbal communication

Nonverbal communication explains the processes that convey a type of information in a form of non-linguistic representations. Examples of nonverbal communication include haptic communication, chronemic communication, gestures, body language, facial expressions, eye contact etc. Nonverbal communication also relates to the intent of a message. Examples of intent are voluntary, intentional movements like shaking a hand or winking, as well as involuntary, such as sweating. Speech also contains nonverbal elements known as paralanguage, e.g. rhythm, intonation, tempo, and stress. It affects communication most at the subconscious level and establishes trust. Likewise, written texts include nonverbal elements such as handwriting style, the spatial arrangement of words and the use of emoticons to convey emotion.

Nonverbal communication demonstrates one of Paul Watzlawick's laws: you cannot not communicate. Once proximity has formed awareness, living creatures begin interpreting any signals received.Wazlawick, Paul (1970's) opus Some of the functions of nonverbal communication in humans are to complement and illustrate, to reinforce and emphasize, to replace and substitute, to control and regulate, and to contradict the denotative message.

Nonverbal cues are heavily relied on to express communication and to interpret others' communication and can replace or substitute verbal messages.

There are several reasons as to why non-verbal communication plays a vital role in communication:
"Non-verbal communication is omnipresent."(Burgoon, J., Guerrero, L., Floyd, K., (2010). Nonverbal Communication, Taylor & Francis. p. 3 ) They are included in every single communication act. To have total communication, all non-verbal channels such as the body, face, voice, appearance, touch, distance, timing, and other environmental forces must be engaged during face-to-face interaction. Written communication can also have non-verbal attributes. E-mails, web chats, and the social media have options to change text font colours, stationery, add emoticons, capitalization, and pictures in order to capture non-verbal cues into a verbal medium.
"Non-verbal behaviours are multifunctional."(Burgoon et al., p. 4) Many different non-verbal channels are engaged at the same time in communication acts and allow the chance for simultaneous messages to be sent and received.
"Non-verbal behaviours may form a universal language system." Smiling, crying, pointing, caressing, and glaring are non-verbal behaviours that are used and understood by people regardless of nationality. Such non-verbal signals allow the most basic form of communication when verbal communication is not effective due to language barriers.

When verbal messages contradict non-verbal messages, observation of non-verbal behaviour is relied on to judge another's attitudes and feelings, rather than assuming the truth of the verbal message alone.

Non verbal communication can take the following forms:
 Paralinguistics are the elements other than language where the voice is involved in communication and includes tones, pitch, vocal cues etc. It also includes sounds from throat and all these are greatly influenced by cultural differences across borders.
 Proxemics deals with the concept of the space element in communication. Proxemics explains four zones of spaces, namely intimate, personal, social and public. This concept differs from culture to culture as the permissible space varies in different countries.
 Artifactics studies the non verbal signals or communication which emerges from personal accessories such as the dress or fashion accessories worn and it varies with culture as people of different countries follow different dress codes.
 Chronemics deals with the time aspects of communication and also includes the importance given to time. Some issues explaining this concept are pauses, silences and response lag during an interaction. This aspect of communication is also influenced by cultural differences as it is well known that there is a great difference in the value given by different cultures to time.
 Kinesics mainly deals with body language such as postures, gestures, head nods, leg movements, etc. In different countries, the same gestures and postures are used to convey different messages. Sometimes even a particular kinesic indicating something good in a country may have a negative meaning in another culture.

Communication models

Models of communication are conceptual representations of the process of communication. Their goal is to provide a simplified overview of its main components. This makes it easier for researchers to formulate hypotheses, apply communication-related concepts to real-world cases, and test predictions. However, it is often argued that many models lack the conceptual complexity needed for a comprehensive understanding of all the essential aspects of communication. They are usually presented visually in the form of diagrams showing various basic components and their interaction.

Models of communication are often categorized based on their intended applications and how they conceptualize communication. Some models are general in the sense that they are intended for all forms of communication. They contrast with specialized models, which aim to describe only certain forms of communication, like models of mass communication. An influential classification distinguishes between linear transmission models, interaction models, and transaction models. Linear transmission models focus on how a sender transmits information to a receiver. They are linear because this flow of information only goes in one direction. This view is rejected by interaction models, which include a feedback loop. Feedback is required to describe many forms of communication, such as a regular conversation, where the listener may respond by expressing their opinion on the issue or by asking for clarification. For interaction models, communication is a two-way-process in which the communicators take turns in sending and receiving messages. Transaction models further refine this picture by allowing sending and responding to happen at the same time. This modification is needed, for example, to describe how the listener in a face-to-face conversation gives non-verbal feedback through their body posture and their facial expressions while the other person is talking. Transaction models also hold that meaning is produced during communication and does not exist independent of it.

thumb|upright=1.5|alt=Diagram of Lasswell's model|Lasswell's model is based on five questions corresponding to five basic components.
All the early models, developed in the middle of the 20th century, are linear transmission models. Lasswell's model, for example, is based on five fundamental questions: "Who?", "Says What?", "In What Channel?", "To Whom?", and "With What Effect?". The goal of these questions is to identify the basic components involved in the communicative process: the sender, the message, the channel, the receiver, and the effect. Lasswell's model was initially only conceived as a model of mass communication, but it has been applied to various other fields as well. Some theorists have expanded it by including additional questions, like "Under What Circumstances?" and "For What Purpose?".

thumb|upright=1.5|alt=Diagram of the Shannon–Weaver model|The Shannon–Weaver model focuses on how a message is first translated into a signal and then back into a message.
The Shannon–Weaver model is another influential linear transmission model. It is based on the idea that a source creates a message, which is then translated into a signal by a transmitter. Noise may interfere and distort the signal. Once the signal reaches the receiver, it is translated back into a message and made available to the destination. For a landline telephone call, the person calling is the source and their telephone is the transmitter. It translates the message into an electrical signal that travels through the wire, which acts as the channel. The person taking the call is the destination and their telephone is the receiver. The Shannon–Weaver model includes an in-depth discussion of how noise can distort the signal and how successful communication can be achieved despite noise. This can happen, for example, by making the message partially redundant so that decoding is possible nonetheless. Other influential linear transmission models include Gerbner's model and Berlo's model.

thumb|upright=1.5|alt=Diagram of the feedback loop in Schramm's model of communication|Central to Schramm's model are the processes of encoding and decoding as well as feedback.
The earliest interaction model is due to Wilbur Schramm. For him, communication starts when a source has an idea and expresses it in the form of a message. This process is called encoding and happens using a code, i.e. a sign system that is able to express the idea, for example, through visual or auditory signs. The message is sent to a destination, who has to decode and interpret it in order to understand it. In response, they formulate their own idea, encode it into a message and send it back as a form of feedback. Another important innovation of Schramm's model is that previous experience is necessary to be able to encode and decode messages. For communication to be successful, the fields of experience of source and destination have to overlap.

thumb|upright=1.5|alt=Diagram of Barnlund's model of interpersonal communication|Barnlund's model of interpersonal communication. The orange arrows show how the communicators decode cues and the yellow arrows symbolize their behavioral responses.
The first transactional model was proposed by Dean Barnlund. He understands communication as "the production of meaning, rather than the production of messages". Its goal is to decrease uncertainty and arrive at a shared understanding. This happens in response to external and internal cues. Decoding is the process of ascribing meaning to them and encoding consists in producing new behavioral cues as a response.

As an academic discipline

The academic discipline that deals with processes of human communication is communication studies. The discipline encompasses a range of topics, from face-to-face conversation to mass media outlets such as television broadcasting. Communication studies also examines how messages are interpreted through the political, cultural, economic, semiotic, hermeneutic, and social dimensions of their contexts. Statistics, as a quantitative approach to communication science, has also been incorporated into research on communication science in order to help substantiate claims.

Organizational communication

Business communication is used for a wide variety of activities including, but not limited to: strategic communications planning, media relations, internal communications, public relations (which can include social media, broadcast and written communications, and more), brand management, reputation management, speech-writing, customer-client relations, and internal/employee communications.

Companies with limited resources may choose to engage in only a few of these activities, while larger organizations may employ a full spectrum of communications. Since it is relatively difficult to develop such a broad range of skills, communications professionals often specialize in one or two of these areas but usually have at least a working knowledge of most of them. By far, the most important qualifications communications professionals must possess are excellent writing ability, good 'people' skills, and the capacity to think critically and strategically.

Business communication could also refer to the style of communication within a given corporate entity (i.e. email conversation styles, or internal communication styles).

The Classical Approach:

The classical approach comes from the management theory by Frederick Taylor who was the founder of the scientific management theory as well.EVALUATE THE INFLUENCE OF CLASSICAL AND HUMAN RELATIONS APPROACHES IN MANAGEMENT TODAY The main idea of the classical approach of organizational communication is that the theory compares organizations to a machine. The theory observed and analyze that workers perform the task they are given to in order to contribute to the overall well-being of the organization. Each member has their purpose in the group, just like a part of a machine works does its tasks while cooperate with other parts to have a well-managed, functioning machine. Additionally, just like a machine that collapse when one part fails to function. An organization will fall apart when members are not doing their designated task appropriately.

The Human Relation Approach:

The human relation approach is based from several different theorists such as: Elton Mayo, McGregors's Douglas, Abraham Maslow, Mary Parker Follett's and Argyris. The main idea of the human relation approach of organizational communication is that the theory compares organizations to a family. As this theory compares organization to a family, it focuses on workers satisfaction and the relationship within the organizations more compared to the work performance element. The human relation approach emphasizes the importance of employee attitudes, and encourage organizations management team to focus on interpersonal relationships, group dynamics, and leadership styles in achieving organizational effectiveness.

Political communication
Communication is one of the most relevant tools in political strategies, including persuasion and propaganda. In mass media research and online media research, the effort of the strategist is that of getting a precise decoding, avoiding "message reactance", that is, message refusal. The reaction to a message is referred also in terms of approach to a message, as follows:
 In "radical reading" the audience rejects the meanings, values, and viewpoints built into the text by its makers. Effect: message refusal.
 In "dominant reading", the audience accepts the meanings, values, and viewpoints built into the text by its makers. Effect: message acceptance.
 In "subordinate reading" the audience accepts, by and large, the meanings, values, and worldview built into the text by its makers. Effect: obey to the message.Danesi, Marcel (2009), Dictionary of Media and Communications. M.E.Sharpe, Armonk, New York.
Holistic approaches are used by communication campaign leaders and communication strategists in order to examine all the options, "actors" and channels that can generate change in the semiotic landscape, that is, change in perceptions, change in credibility, change in the "memetic background", change in the image of movements, of candidates, players and managers as perceived by key influencers that can have a role in generating the desired "end-state".

The modern political communication field is highly influenced by the framework and practices of "information operations" doctrines that derive their nature from strategic and military studies. According to this view, what is really relevant is the concept of acting on the Information Environment. The information environment is the aggregate of individuals, organizations, and systems that collect, process, disseminate, or act on information. This environment consists of three interrelated dimensions, which continuously interact with individuals, organizations, and systems. These dimensions are known as physical, informational, and cognitive.

Interpersonal communication

Interpersonal communication is communication which takes place between two or more individuals. Both verbal communication and nonverbal communication (including body language) affect how one person understands another. 

Verbal interpersonal communication involves the exchange of content messages and relational messages. Content messages express the speaker's feelings towards the topic of discussion. Relational messages demonstrate the speaker's feelings towards their relationship with the other participants. Relational messages come across in how one says something.

Interpersonal communication also encompasses:
 Audiovisual perception of communication problems.Barkhuysen, P., Krahmer, E., Swerts, M., (2004) Audiovisual Perception of Communication Problems, ISCA Archive http://www.isca-speech.org/archive  The concept follows the idea that our words change what form they take based on the stress level or urgency of the situation. It also explores the concept that stuttering during speech shows the audience that there is a problem or that the situation is more stressful.
 Attachment theory.Bretherton, I., (1992) The Origins of Attachment Theory: John Bowlby and Mary Ainsworth, Developmental Psychology, 28, 759-775 This theory follows the relationships that builds between a mother and child, and the impact it has on their relationships with others. It resulted from the combined work of John Bowlby and Mary Ainsworth (Ainsworth & Bowlby, 1991).
 Emotional intelligence and triggers.Mazza, J., Emotional Triggers, MABC, CPC Emotional Intelligence focuses on the ability to monitor ones own emotions as well as those of others. Emotional Triggers focus on events or people that tend to set off intense, emotional reactions within individuals.
 Attribution theory, the study of how individuals explain what causes different events and behaviors.Bertram, M., (2004) How the Mind Explains Behavior: Folk Explanations, Meaning, and Social Interaction, MIT Press,  
 The Power of Words (Verbal communications). Verbal communication focuses heavily on the power of words, and how those words are said. It takes into consideration tone, volume, and choice of words.
 Nonverbal communication, including the setting in which words are conveyed and the physical tone of the words.
 Ethics in personal relations.Lipthrott, D., What IS Relationship? What is Ethical Partnership? This considers a space of mutual responsibility between two individuals, including giving and receiving in a relationship. This theory is explored by Dawn J. Lipthrott in the article "What IS Relationship? What is Ethical Partnership?"
 Deception in communication.Hearn, J., (2006) Interpersonal Deception Theory: Ten Lessons for Negotiators This concept is based on the premise that everyone lies and considers how lying impacts relationships. James Hearn explores this theory in his article, "Interpersonal Deception Theory: Ten Lessons for Negotiators."
 Conflict in couples.Lenhart, A., Duggan, M., (2014) Couples, the Internet, and Social Media This focuses on the impact that social media has on relationships, as well as how to communicate through conflict. This theory is explored by Amanda Lenhart and Maeve Duggan in their paper, "Couples, the Internet, and Social Media."

 Family communication 
Family communication is the study of the communication perspective in a broadly defined family, with intimacy and trusting relationship.Turner, L.H., & West, R.L. (2013). Perspectives on family communication. Boston: McGraw-Hill. The main goal of family communication is to understand the interactions of family and the pattern of behaviors of family members in different circumstances. Open and honest communication creates an atmosphere that allows family members to express their differences as well as love and admiration for one another. It also helps to understand the feelings of one another.

Family communication study looks at topics such as family rules, family roles or family dialectics and how those factors could affect the communication between family members. Researchers develop theories to understand communication behaviors. Family communication study also digs deep into certain time periods of family life such as marriage, parenthood or divorce and how communication stands in those situations. It is important for family members to understand communication as a trusted way which leads to a well constructed family.

 Rhetoric 
According to scholar Anne Beaufort, communication is also interested in rhetoric as a method of investigating "oral and written communications, particularly with regard to the desired effect on an audience, and lately, with visual communications as well."Beaufort, Anne. "Rhetorical Studies, Communications, and Composition Studies: Disparate or Overlapping Discourse Communities." The Realms of Rhetoric.

Barriers to effectiveness
Barriers to effective communication can distort the message or intention of the message being conveyed. This may result in failure of the communication process or cause an effect that is undesirable. These include filtering, selective perception, information overload, emotions, language, silence, communication apprehension, gender differences and political correctness.Robbins, S., Judge, T., Millett, B., & Boyle, M. (2011). Organisational Behaviour. 6th ed. Pearson, French's Forest, NSW pp. 315–317.

Noise
In any communication model, noise is interference with the decoding of messages sent over the channel by an encoder. To face communication noise, redundancy and acknowledgement must often be used. Acknowledgements are messages from the addressee informing the originator that his/her communication has been received and is understood.North Atlantic Treaty Organization, NATO Standardization Agency AAP-6 – Glossary of terms and definitions, p. 43. Message repetition and feedback about message received are necessary in the presence of noise to reduce the probability of misunderstanding.

The act of disambiguation regards the attempt of reducing noise and wrong interpretations, when the semantic value or meaning of a sign can be subject to noise, or in presence of multiple meanings, which makes the sense-making difficult. Disambiguation attempts to decrease the likelihood of misunderstanding. This is also a fundamental skill in communication processes activated by counselors, psychotherapists, interpreters, and in coaching sessions based on colloquium. In Information Technology, the disambiguation process and the automatic disambiguation of meanings of words and sentences has also been an interest and concern since the earliest days of computer treatment of language.Nancy Ide, Jean Véronis. "Word Sense Disambiguation: The State of the Art", Computational Linguistics, 24(1), 1998, pp. 1–40.

Cultural aspects
Cultural differences exist within countries (tribal/regional differences, dialects and so on), between religious groups and in organisations or at an organisational level – where companies, teams and units may have different expectations, norms and idiolects. Families and family groups may also experience the effect of cultural barriers to communication within and between different family members or groups. For example: words, colours and symbols have different meanings in different cultures. In most parts of the world, nodding your head means agreement, shaking your head means "no", but this is not true everywhere.Nageshwar Rao, Rajendra P. Das, Communication skills, Himalaya Publishing House, 9789350516669, p. 48

Communication to a great extent is influenced by culture and cultural variables. Understanding cultural aspects of communication refers to having knowledge of different cultures in order to communicate effectively with cross culture people. Cultural aspects of communication are of great relevance in today's world which is now a global village, thanks to globalisation. Cultural aspects of communication are the cultural differences which influence communication across borders. So in order to have an effective communication across the world it is desirable to have a knowledge of cultural variables effecting communication.

According to Michael Walsh and Ghil'ad Zuckermann, Western conversational interaction is typically "dyadic", between two particular people, where eye contact is important and the speaker controls the interaction; and "contained" in a relatively short, defined time frame. However, traditional Aboriginal conversational interaction is "communal", broadcast to many people, eye contact is not important, the listener controls the interaction; and "continuous", spread over a longer, indefinite time frame.

Nonhuman

Every information exchange between living organisms — i.e. transmission of signals that involve a living sender and receiver can be considered a form of communication; and even primitive creatures such as corals are competent to communicate. Nonhuman communication also include cell signaling, cellular communication, and chemical transmissions between primitive organisms like bacteria and within the plant and fungal kingdoms.

Animals
The broad field of animal communication encompasses most of the issues in ethology. Animal communication can be defined as any behavior of one animal that affects the current or future behavior of another animal. The study of animal communication, called zoo semiotics (distinguishable from anthroposemiotics, the study of human communication) has played an important part in the development of ethology, sociobiology, and the study of animal cognition. Animal communication, and indeed the understanding of the animal world in general, is a rapidly growing field, and even in the 21st century so far, a great share of prior understanding related to diverse fields such as personal symbolic name use, animal emotions, animal culture and learning, and even sexual conduct, long thought to be well understood, has been revolutionized.

Plants and fungi
Communication is observed within the plant organism, i.e. within plant cells and between plant cells, between plants of the same or related species, and between plants and non-plant organisms, especially in the root zone. Plant roots communicate with rhizome bacteria, fungi, and insects within the soil. Recent research has shown that most of the microorganism plant communication processes are neuron-like. Plants also communicate via volatiles when exposed to herbivory attack behavior, thus warning neighboring plants. In parallel they produce other volatiles to attract parasites which attack these herbivores.

Fungi communicate to coordinate and organize their growth and development such as the formation of mycelia and fruiting bodies. Fungi communicate with their own and related species as well as with non fungal organisms in a great variety of symbiotic interactions, especially with bacteria, unicellular eukaryote, plants and insects through biochemicals of biotic origin. The biochemicals trigger the fungal organism to react in a specific manner, while if the same chemical molecules are not part of biotic messages, they do not trigger the fungal organism to react. This implies that fungal organisms can differentiate between molecules taking part in biotic messages and similar molecules being irrelevant in the situation. So far five different primary signalling molecules are known to coordinate different behavioral patterns such as filamentation, mating, growth, and pathogenicity. Behavioral coordination and production of signaling substances is achieved through interpretation processes that enables the organism to differ between self or non-self, a biotic indicator, biotic message from similar, related, or non-related species, and even filter out "noise", i.e. similar molecules without biotic content.

Pheromones are molecules released by one organism into the external environment to influence other individuals of the same species. Thus pheromone release is a form of communication. Pheromones promote sexual interaction (mating) in several fungal species. These include the aquatic fungus Allomyces macrogynus, the Mucorales fungus Mucor mucedo, Neurospora crassa and the yeasts Saccharomyces cerevisiae, Schizosaccharomyces pombe and Rhodosporidium toruloides.O’Day, D.H. (1981). Modes of cellular communicatin and sexual interactions in eukaryotic microbes.  In: Sexual Interactions in Eukaryotic Microbes.  (O’Day, D.H. & Horgen, P.A., eds), pp. 3-17. New York: Academic Press

Bacteria quorum sensing
Communication is not a tool used only by humans, plants and animals, but it is also used by microorganisms like bacteria. The process is called quorum sensing. Through quorum sensing, bacteria can sense the density of cells, and regulate gene expression accordingly. This can be seen in both gram positive and gram negative bacteria.
This was first observed by Fuqua et al. in marine microorganisms like V. harveyi and V. fischeri.Anand, Sandhya. Quorum Sensing- Communication Plan For Microbes . Article dated 2010-12-28, retrieved on 2012-04-03.

Natural bacterial transformation involves the transfer of naked DNA from one bacterium to another through the surrounding medium, and can be regarded as a relatively simple form of sexual interaction. In several bacterial species transformation is promoted by the production of an extracellular factor, termed a competence factor, that when released into the surrounding medium induces a state of competence in neighboring cells. The state of competence is the ability to take up the DNA released by another cell. Bacterial competence factors are similar to pheromones in multicellular organisms. Competence factors have been studied in Bacillus subtilis and Streptococcus pneumoniae.

See also

References

Further reading

 

External links
 
 

 
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