Information
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[[Image:WikipediaBinary.svg|thumbnail|right|190px|The [[ASCII]] codes for the word "Wikipedia" represented in [[Binary numeral system|binary]], the numeral system most commonly used for encoding computer information.]]
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'''Information''' as a [[Conveyed concept|concept]] has a diversity of meanings, from everyday usage to technical settings.  Generally speaking, the concept of information is closely related to notions of [[constraint]], [[communication]], [[control system|control]], [[data]], [[form]], [[instruction]], [[knowledge]], [[Meaning (linguistics)|meaning]], [[stimulation|mental stimulus]], [[pattern]], [[perception]], and [[knowledge representation|representation]].

Many people speak about the [[Information Age]] as the advent of the Knowledge Age {{Fact|date=February 2007}}{{weasel word|date=June 2007}} or [[knowledge society]], the [[information society]], the [[Information revolution]], and [[Information technology|information technologies]], and even though [[informatics]], [[information science]] and [[computer science]] are often in the spotlight, the word "information" is often used without careful consideration of the various meanings it has acquired.

== Etymology ==
According to the [[Oxford English Dictionary]], the earliest historical meaning of the word ''information'' in [[English language|English]] was the act of ''informing'', or giving form or shape to the mind, as in education, instruction, or training.  A quote from 1387: "Five books come down from heaven for information of mankind." It was also used for an ''item'' of training, ''e.g.'' a particular instruction.  "Melibee had heard the great skills and reasons of Dame Prudence, and her wise information and techniques." (1386)

The English word was apparently derived by adding the common "noun of action" ending "''-ation''" (descended through Francais from Latin "''-tio''") to the earlier verb ''to inform'', in the sense of to give form to the mind, to discipline, instruct, teach: "Men so wise should go and inform their kings." (1330)  ''Inform'' itself comes (via French) from the Latin verb ''informare'', to give form to, to form an idea of. Furthermore, Latin itself already even contained the word ''informatio'' meaning concept or idea, but the extent to which this may have influenced the development of the word ''information'' in English is unclear.

As a final note, the ancient Greek word for ''form'' was [eidos], and this word was famously used in a technical philosophical sense by [Plato] (and later Aristotle) to denote the ideal identity or essence of something (see [Theory of forms]). "Eidos" can also be associated with [thought], [proposition] or even [concept].

== Information as a message ==

'''Information''' is the state of a system of interest. Message is the information materialized.

Information is a quality of a [[message]] from a [[sender]] to one or more receivers. Information is always ''about'' something (size of a parameter, occurrence of an event, etc). Viewed in this manner, information does not have to be accurate. It may be a truth or a lie, or just the sound of a falling tree. Even a disruptive noise used to inhibit the flow of communication and create misunderstanding would in this view be a form of information.  However, generally speaking, if the ''amount'' of information in the received message increases, the message is more accurate.

This model assumes there is a definite [[sender]] and at least one receiver. Many refinements of the model assume the existence of a common language understood by the sender and at least one of the receivers. An important variation identifies information as that which would be communicated by a message if it were sent from a sender to a receiver capable of understanding the message. Notably, it is not required that the sender be capable of understanding the message, or even cognizant that there is a message.  Thus, information is something that can be extracted from an environment, e.g., through observation, reading or measurement.

Information is a term with many meanings depending on context, but is as a rule closely related to such concepts as meaning, knowledge, instruction, communication, representation, and mental stimulus. Simply stated, information is a message received and understood. In terms of data, it can be defined as a collection of facts from which conclusions may be drawn. There are many other aspects of information since it is the knowledge acquired through study or experience or instruction. But overall, information is the result of processing, manipulating and organizing data in a way that adds to the knowledge of the person receiving it.

[[Communication theory]] provides a numerical measure of the uncertainty of an outcome. For example, we can say that "the signal contained thousands of bits of information".  Communication theory tends to use the concept of [[information entropy]], generally attributed to [[C.E. Shannon]] (see below).

Another form of information is [[Fisher information]], a concept of [[R.A. Fisher]]. This is used in application of statistics to [[estimation theory]] and to science in general.  Fisher information is thought of as the amount of information that a message carries about an unobservable parameter.  It can be computed from knowledge of the [[likelihood function]] defining the system.  For example, with a normal likelihood function, the Fisher information is the reciprocal of the variance of the law.  In the absence of knowledge of the likelihood law, the Fisher information may be computed from normally distributed score data as the reciprocal of their second moment.

Even though information and data are often used interchangeably, they are actually very different. Data is a set of unrelated information, and as such is of no use until it is properly evaluated. Upon evaluation, once there is some significant relation between data, and they show some relevance, then they are converted into information. Now this same data can be used for different purposes. Thus, till the data convey some information, they are not useful.

=== Measuring information entropy ===

The view of information as a message came into prominence with the publication in 1948 of an influential paper by [[Claude Shannon]], "[[A Mathematical Theory of Communication]]."  This paper provides the foundations of [[information theory]] and endows the word ''information'' not only with a technical meaning but also a measure. If the sending device is equally likely to send any one of a set of <math>N</math> messages, then the preferred measure of "the information produced when one message is chosen from the set" is the base two [[logarithm]] of <math>N</math> (This measure is called ''[[self-information]]''). In this paper, Shannon continues:

{{quotation|The [[choice]] of a logarithmic base corresponds to the choice of a [[units of information|unit for measuring information]]. If the base 2 is used the resulting units may be called binary digits, or more briefly [[bit]]s, a word suggested by [[John Tukey|J. W. Tukey]]. A device with two stable positions, such as a relay or a flip-flop circuit, can store one bit of information. N such devices can store N bits…<ref name = "Shannon">The Bell System Technical Journal, Vol. 27, p. 379, (July 1948).</ref>}}

A complementary way of measuring information is provided by [[algorithmic information theory]]. In brief, this measures the information content of a list of symbols based on how predictable they are, or more specifically how easy it is to compute the list through a [[computer program|program]]: the information content of a sequence is the number of bits of the shortest program that computes it. The sequence below would have a very low algorithmic information measurement since it is a very predictable pattern, and as the pattern continues the measurement would not change. Shannon information would give the same information measurement for each symbol, since they are [[statistical randomness|statistically random]], and each new symbol would increase the measurement.
:123456789101112131415161718192021

It is important to recognize the limitations of traditional information theory and algorithmic information theory from the perspective of human meaning. For example, when referring to the meaning content of a message Shannon noted “Frequently the messages have ''meaning…'' these semantic aspects of communication are irrelevant to the engineering problem.  The significant aspect is that the actual message is one selected ''from a set of possible messages''” (emphasis in original).

In information theory signals are part of a process, not a substance; they do something, they do not contain any specific meaning. Combining algorithmic information theory and information theory we can conclude that the most random signal contains the most information as it can be interpreted in any way and cannot be compressed.{{Fact|date=August 2007}}

Michael Reddy noted that "'signals' of the [[mathematical theory]] are 'patterns that can be exchanged'.  There is no message contained in the signal, the signals convey the ability to select from a set of possible messages."  In information theory "the system must be designed to operate for each possible selection, not just the one which will actually be chosen since this is unknown at the time of design".

== Information as a pattern ==

Information is any represented [[pattern]]. This view assumes neither accuracy nor directly communicating parties, but instead assumes a separation between an object and its representation.  Consider the following example: [[economic statistics]] represent an [[Economics|economy]], however inaccurately. What are commonly referred to as data in [[computing]], [[statistics]], and other fields, are forms of information in this sense. The [[electromagnetism|electro-magnetic]] patterns in a [[computer network]] and connected [[peripheral device|device]]s are related to something other than the pattern itself, such as [[Character (computing)|text characters]] to be displayed and [[Computer keyboard|keyboard]] input. [[Signal (information theory)|Signal]]s, [[Sign (linguistics)|sign]]s, and [[symbol]]s are also in this category.  On the other hand, according to [[semiotics]], data is symbols with certain syntax and information is data with a certain semantic.  [[Painting]] and [[drawing]] contain information to the extent that they represent something such as an assortment of objects on a table, a [[profile]], or a [[landscape]]. In other words, when a pattern of something is transposed to a pattern of something else, the latter is information. This would be the case whether or not there was anyone to perceive it.

But if information can be defined merely as a pattern, does that mean that neither [[utility]] nor meaning are necessary components of information? Arguably a distinction must be made between raw unprocessed data and information which possesses utility, [[value (economics)|value]] or some quantum of meaning. On this view, information may indeed be characterized as a pattern; but this is a [[necessary]] condition, not a [[sufficient]] one. 

An individual entry in a telephone book, which follows a specific pattern formed by name, address and telephone number, does not become "informative" in some sense unless and until it possesses some degree of utility, value or meaning. For example, someone might look up a girlfriend's number, might order a take away etc. The vast majority of numbers will never be construed as "information" in any meaningful sense. The gap between data and information is only closed by a behavioral bridge whereby some value, utility or meaning is added to transform mere data or pattern into information.

When one constructs a representation of an object, one can selectively extract from the object ([[sampling (case studies)|sampling]]) or use a [[system]] of signs to replace ([[encode|encoding]]), or both. The sampling and encoding result in representation. An example of the former is a "sample" of a product; an example of the latter is "verbal description" of a product. Both contain information of the product, however inaccurate. When one interprets representation, one can predict a broader pattern from a limited number of observations (inference) or understand the relation between patterns of two different things ([[decode|decoding]]). One example of the former is to sip a [[soup]] to know if it is spoiled; an example of the latter is examining footprints to determine the animal and its condition. In both cases, information sources are not constructed or presented by some "sender" of information. 
Regardless, information is dependent upon, but usually unrelated to and separate from, the medium or media used to express it. In other words, the position of a theoretical series of bits, or even the output once interpreted by a [[computer]] or similar device, is unimportant, except when someone or something is present to interpret the information. Therefore, a quantity of information is totally distinct from its medium.

== Information as sensory input ==

Often information is viewed as a type of [[input]] to an [[organism]] or designed device. Inputs are of two kinds. Some inputs are important to the function of the organism (for example, food) or device ([[energy]]) by themselves. In his book ''Sensory Ecology,'' Dusenbery<!-- who? --> called these causal inputs. Other inputs (information) are important only because they are associated with causal inputs and can be used to predict the occurrence of a causal input at a later time (and perhaps another place). Some information is important because of association with other information but eventually there must be a connection to a causal input. In practice, information is usually carried by weak stimuli that must be detected by specialized sensory systems and amplified by energy inputs before they can be functional to the organism or device. For example, light is often a causal input to plants but provides information to animals. The colored light reflected from a flower is too weak to do much photosynthetic work but the visual system of the bee detects it and the bee's nervous system uses the information to guide the bee to the flower, where the bee often finds nectar or pollen, which are causal inputs, serving a nutritional function.

Information is any type of sensory input. When an organism with a [[nervous system]] receives an input, it transforms the input into an electrical signal. This is regarded information by some. The idea of representation is still relevant, but in a slightly different manner. That is, while [[abstract painting]] does not represent anything concretely, when the viewer sees the painting, it is nevertheless transformed into electrical signals that create a representation of the painting. Defined this way, information does not have to be related to truth, communication, or representation of an object. [[Entertainment]] in general is not intended to be informative. [[Music]], the [[performing arts]], [[amusement park]]s, works of [[fiction]] and so on are thus forms of information in this sense, but they are not necessarily forms of information according to some definitions given above. Consider another example: food supplies both nutrition and taste for those who eat it. If information is equated to sensory input, then nutrition is not information but taste is.

== Information as an influence which leads to a transformation ==

Information is any type of pattern that influences the formation or transformation of other patterns. In this sense, there is no need for a conscious mind to perceive, much less appreciate, the pattern. Consider, for example, [[DNA]]. The sequence of [[nucleotide]]s is a pattern that influences the formation and development of an organism without any need for a conscious mind.  [[Systems theory]] at times seems to refer to information in this sense, assuming information does not necessarily involve any conscious mind, and patterns circulating (due to [[feedback]]) in the system can be called information. In other words, it can be said that information in this sense is something potentially perceived as representation, though not created or presented for that purpose.

When [[Marshall McLuhan]] speaks of [[media (communication)|media]] and their effects on human cultures, he refers to the structure of [[cultural artifact|artifacts]] that in turn shape our behaviors and mindsets. Also, [[pheromone]]s are often said to be "information" in this sense.

(See also [[Gregory Bateson]].)

== Information as a property in physics ==

{{main|Physical information}}

In 2003, J. D. Bekenstein claimed there is a growing trend in [[physics]] to define the physical world as being made of information itself (and thus information is defined in this way). Information has a well defined meaning in physics. Examples of this include the phenomenon of [[quantum entanglement]] where particles can interact without reference to their separation or the speed of light. Information itself cannot travel faster than light even if the information is transmitted indirectly. This could lead to the fact that all attempts at physically observing a particle with an "entangled" relationship to another are slowed down, even though the particles are not connected in any other way other than by the information they carry.

Another link is demonstrated by the [[Maxwell's demon]] thought experiment.  In this experiment, a direct relationship between information and another physical property, [[entropy]], is demonstrated.  A consequence is that it is impossible to destroy information without increasing the entropy of a system; in practical terms this often means generating heat. Another, more philosophical, outcome is that information could be thought of as interchangeable with [[Energy#Transformations_of_energy|energy]].  Thus, in the study of [[logic gates]], the theoretical lower bound of thermal energy released by an ''AND gate'' is higher than for the ''NOT gate'' (because information is destroyed in an ''AND gate'' and simply converted in a ''NOT gate''). Physical information is of particular importance in the theory of [[quantum computers]].

== Information as records ==

Records are a specialized form of information. Essentially, records are information produced consciously or as by-products of business activities or transactions and retained because of their value.  Primarily their value is as evidence of the activities of the organization but they may also be retained for their informational value.  Sound [[records management]] ensures that the integrity of records is preserved for as long as they are required.

The international standard on records management, ISO 15489, defines records as "information created, received, and maintained as evidence and information by an organization or person, in pursuance of legal obligations or in the transaction of business". The International Committee on Archives (ICA) Committee on electronic records defined a record as, "a specific piece of recorded information generated, collected or received in the initiation, conduct or completion of an activity and that comprises sufficient content, context and structure to provide proof or evidence of that activity".

Records may be retained because  of their business value, as part of the [[corporate memory]] of the organization or to meet legal, fiscal or accountability requirements imposed on the organization. Willis (2005) expressed the view that sound management of business records and information delivered "…six key requirements for good [[corporate governance]]…transparency; accountability; due process; compliance; meeting statutory and common law requirements; and security of personal and corporate information."

== Information and semiotics ==
Beynon-Davies <ref>Beynon-Davies P. (2002). Information Systems: an introduction to informatics in Organisations. Palgrave, Basingstoke, UK. ISBN: 0-333-96390-3</ref> explains the multi-faceted concept of information in terms of that of signs and sign-systems. Signs themselves can be considered in terms of four inter-dependent levels, layers or branches of [[semiotics]]: pragmatics, semantics, syntactics and empirics. These four layers serve to connect the social world on the one hand with the physical or technical world on the other.

[[Pragmatics]] is concerned with the purpose of communication. Pragmatics links the issue of signs with that of intention. The focus of pragmatics is on the intentions of human agents underlying communicative behaviour. In other words, intentions link language to action.

[[Semantics]] is concerned with the meaning of a message conveyed in a communicative act. Semantics considers the content of communication. Semantics is the study of the meaning of signs - the association between signs and behaviour. Semantics can be considered as the study of the link between symbols and their referents or concepts; particularly the way in which signs relate to human behaviour.

Syntactics is concerned with the formalism used to represent a message. Syntactics as an area studies the form of communication in terms of the logic and grammar of sign systems. Syntactics is devoted to the study of the form rather than the content of signs and sign-systems.

Empirics is the study of the signals used to carry a message; the physical characteristics of the medium of communication. Empirics is devoted to the study of communication channels and their characteristics, e.g., sound, light, electronic transmission etc.

Communication normally exists within the context of some social situation. The social situation sets the context for the intentions conveyed (pragmatics) and the form in which communication takes place. In a communicative situation intentions are expressed through messages which comprise collections of inter-related signs taken from a language which is mutually understood by the agents involved in the communication. Mutual understanding implies that agents involved understand the chosen language in terms of its agreed syntax (syntactics) and semantics. The sender codes the message in the language and sends the message as signals along some communication channel (empirics). The chosen communication channel will have inherent properties which determine outcomes such as the speed with which communication can take place and over what distance.

== References ==
{{reflist}}

== Further reading ==
* Alan Liu (2004). ''The Laws of Cool: Knowledge Work and the Culture of Information'', [[University of Chicago Press]]
* Bekenstein, Jacob D. (2003, August). Information in the [[holographic principle|holographic universe]]. ''Scientific American''. 
* [[Luciano Floridi]], (2005). 'Is Information Meaningful Data?', ''Philosophy and Phenomenological Research'', 70 (2), pp. 351 - 370. Available online at [http://www.wolfson.ox.ac.uk/~floridi/pdf/iimd.pdf Oxford University]
* [[Luciano Floridi]], (2005). 'Semantic Conceptions of Information', ''The Stanford Encyclopedia of Philosophy'' (Winter 2005 Edition), Edward N. Zalta (ed.). Available online at [http://plato.stanford.edu/entries/information-semantic/ Stanford University]

== See also ==
{{col-begin}}
{{col-break}}
* [[Informatics]]
* [[Information architecture]]
* [[Information broker]]
* [[Information communication technology]]
* [[Information entropy]]
* [[Information geometry]]
* [[Information highway]]
* [[Information ladder]]
* [[Information mapping]]
* [[Information overload]]
* [[Information processing]]
* [[Information processor]]
* [[Information revolution]]
* [[Information sensitivity]]
* [[Information science]]
* [[Information system]]
* [[Information technology]]
{{col-break}}
* [[Information theory]]
* [[Infosphere]]
* [[Accuracy]]
* [[Abstraction]]
* [[Algorithmic information theory]]
* [[Classified information]]
* [[Complexity]]
** [[Complex system]]
** [[Complex adaptive system]]
* [[Cybernetics]]
* [[Exformation]]
* [[Fisher information]]
* [[Free Information Infrastructure]]
* [[Freedom of information]]
* [[Infornography]]
{{col-break}}
* [[Library and Information Science]]
* [[Recording medium|Medium]]
* [[Metadata]]
* [[Observation]]
* [[Philosophy of information]]
* [[Physical information]]
* [[Prediction]]
* [[Propaganda model]]
* [[Relevance]]
* [[Receiver operating characteristic]]
* [[Satisficing]]
* [[Shannon–Hartley theorem]]
** [[Claude Shannon]]
** [[Ralph Hartley]]
* [[Systems theory]]
{{col-end}}

{{Technology}}

==External links==
{{wiktionary|Information}}
* [http://plato.stanford.edu/entries/information-semantic/ Semantic Conceptions of Information] Review by [[Luciano Floridi]] for the [[Stanford Encyclopedia of Philosophy]]
* [http://pespmc1.vub.ac.be/ASC/NEGENTROPY.html Principia Cybernetica entry on negentropy]
* [http://www.optics.arizona.edu/Frieden/Fisher_Information.htm Fisher Information, a New Paradigm for Science: Introduction, Uncertainty principles, Wave equations, Ideas of Escher, Kant, Plato and Wheeler.] This essay is continually revised in the light of ongoing research.
* [http://www2.sims.berkeley.edu/research/projects/how-much-info-2003/index.htm How Much Information? 2003] an attempt to estimate how much new information is created each year (study was produced by faculty and students at the [[UC Berkeley School of Information|School of Information Management and Systems]] at the [[University of California at Berkeley]].)

[[Category:Information| ]]
[[Category:Information, knowledge, and uncertainty]]

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