Concepts of information
A wide-ranging discussion by 39 scientists on the nature and goals of the information, computer, communication, and systems sciences appears in FRITZ MACHLUP and UNA MANSFIELD (eds.), The Study of Information: Interdisciplinary Messages (1983). Fundamental concepts of information representation and processes are dealt with, sometimes speculatively, in MARVIN MINSKY, The Society of Mind (1986, reissued 1988); ALLEN NEWELL and HERBERT A. SIMON, Human Problem Solving (1972); HERBERT A. SIMON, The Sciences of the Artificial, 3rd ed. (1996); and RONALD J. BRACHMAN, HECTOR J. LEVESQUE, and RAYMOND REITER (eds.), Knowledge Representation (1992). The impact of information technology on making human recorded knowledge available was first visualized in VANNEVAR BUSH, “As We May Think,” Atlantic Monthly, 176:101–108 (July 1945).

Information processing
A comprehensive, basic survey is offered in STEVEN L. MANDELL and SACHI SAKTHIVEL, Computers and Information Processing: Concepts and Applications, 7th ed. (1999). CARLO BATINI, STEFANO CERI, and SHAMKANT B. NAVATHE, Conceptual Database Design: An Entity-Relationship Approach (1992), offers technical but highly readable coverage of this central area of information systems engineering. MARTIN P. CLARK, Networks and Telecommunications: Design and Operation, 2nd ed. (1997), is a readable introduction to the fundamentals of computer networks, their design, and their management.

Public information utilities
The broad view of library networking in the United States given in SUSAN K. MARTIN, Library Networks, 1986–87: Libraries in Partnership (1986), remains representative of current trends. Cooperative arrangements in Europe are discussed in KARL WILHELM NEUBAUER and ESTHER K. DYER (eds.), European Library Networks (1990). Access guides to information resources in printed form are exemplified by ELLIS MOUNT and BEATRICE KOVACS, Using Science and Technology Information Sources (1991). Readers interested in the plans of the U.S. information community may consult ASSOCIATION OF RESEARCH LIBRARIES, Linking Researchers and Resources: The Emerging Information Infrastructure and the NREN Proposal (1990); the Canadian vision is described in GARY CLEVELAND, Research Networks and Libraries: Applications and Issues for a Global Information Network (1991).

information processing , the acquisition, recording, organization, retrieval, display, and dissemination of information. In recent years, the term has often been applied to computer-based operations specifically.

In popular usage, the term information refers to facts and opinions provided and received during the course of daily life: one obtains information directly from other living beings, from mass media, from electronic data banks, and from all sorts of observable phenomena in the surrounding environment. A person using such facts and opinions generates more information, some of which is communicated to others during discourse, by instructions, in letters and documents, and through other media. Information organized according to some logical relationships is referred to as a body of knowledge, to be acquired by systematic exposure or study. Application of knowledge (or skills) yields expertise, and additional analytic or experiential insights are said to constitute instances of wisdom. Use of the term information is not restricted exclusively to its communication via natural language. Information is also registered and communicated through art and by facial expressions and gestures or by such other physical responses as shivering. Moreover, every living entity is endowed with information in the form of a genetic code. These information phenomena permeate the physical and mental world, and their variety is such that it has defied so far all attempts at a unified definition of information.

Interest in information phenomena increased dramatically in the 20th century, and today they are the objects of study in a number of disciplines, including philosophy, physics, biology, linguistics, information and computer science, electronic and communications engineering, management science, and the social sciences. On the commercial side, the information service industry has become one of the newer industries worldwide. Almost all other industries—manufacturing and service—are increasingly concerned with information and its handling. The different, though often overlapping, viewpoints and phenomena of these fields lead to different (and sometimes conflicting) concepts and “definitions” of information.

This article touches on such concepts as they relate to information processing. In treating the basic elements of information processing, it distinguishes between information in analog and digital form, and it describes its acquisition, recording, organization, retrieval, display, and techniques of dissemination. A separate article, information system, covers methods for organizational control and dissemination of information.

General considerations
Basic concepts
Interest in how information is communicated and how its carriers convey meaning has occupied, since the time of pre-Socratic philosophers, the field of inquiry called semiotics, the study of signs and sign phenomena. Signs are the irreducible elements of communication and the carriers of meaning. The American philosopher, mathematician, and physicist Charles S. Peirce is credited with having pointed out the three dimensions of signs, which are concerned with, respectively, the body or medium of the sign, the object that the sign designates, and the interpretant or interpretation of the sign. Peirce recognized that the fundamental relations of information are essentially triadic; in contrast, all relations of the physical sciences are reducible to dyadic (binary) relations. Another American philosopher, Charles W. Morris, designated these three sign dimensions syntactic, semantic, and pragmatic, the names by which they are known today.

Information processes are executed by information processors. For a given information processor, whether physical or biological, a token is an object, devoid of meaning, that the processor recognizes as being totally different from other tokens. A group of such unique tokens recognized by a processor constitutes its basic “alphabet”; for example, the dot, dash, and space constitute the basic token alphabet of a Morse-code processor. Objects that carry meaning are represented by patterns of tokens called symbols. The latter combine to form symbolic expressions that constitute inputs to or outputs from information processes and are stored in the processor memory.

Information processors are components of an information system, which is a class of constructs. An abstract model of an information system features four basic elements: processor, memory, receptor, and effector (Figure 1). The processor has several functions: (1) to carry out elementary information processes on symbolic expressions, (2) to store temporarily in the processor’s short-term memory the input and output expressions on which these processes operate and that they generate, (3) to schedule execution of these processes, and (4) to change this sequence of operations in accordance with the contents of the short-term memory. The memory stores symbolic expressions, including those that represent composite information processes, called programs. The two other components, the receptor and the effector, are input and output mechanisms whose functions are, respectively, to receive symbolic expressions or stimuli from the external environment for manipulation by the processor and to emit the processed structures back to the environment.

The power of this abstract model of an information-processing system is provided by the ability of its component processors to carry out a small number of elementary information processes: reading; comparing; creating, modifying, and naming; copying; storing; and writing. The model, which is representative of a broad variety of such systems, has been found useful to explicate man-made information systems implemented on sequential information processors.

Because it has been recognized that in nature information processes are not strictly sequential, increasing attention has been focused since 1980 on the study of the human brain as an information processor of the parallel type. The cognitive sciences, the interdisciplinary field that focuses on the study of the human mind, have contributed to the development of neurocomputers, a new class of parallel, distributed-information processors that mimic the functioning of the human brain, including its capabilities for self-organization and learning. So-called neural networks, which are mathematical models inspired by the neural circuit network of the human brain, are increasingly finding applications in areas such as pattern recognition, control of industrial processes, and finance, as well as in many research disciplines.

Information as a resource and commodity
In the late 20th century, information acquired two major utilitarian connotations. On the one hand, it is considered an economic resource, somewhat on par with other resources such as labour, material, and capital. This view stems from evidence that the possession, manipulation, and use of information can increase the cost-effectiveness of many physical and cognitive processes. The rise in information-processing activities in industrial manufacturing as well as in human problem solving has been remarkable. Analysis of one of the three traditional divisions of the economy, the service sector, shows a sharp increase in information-intensive activities since the beginning of the 20th century. By 1975 these activities accounted for half of the labour force of the United States.

As an individual and societal resource, information has some interesting characteristics that separate it from the traditional notions of economic resources. Unlike other resources, information is expansive, with limits apparently imposed only by time and human cognitive capabilities. Its expansiveness is attributable to the following: (1) it is naturally diffusive, (2) it reproduces rather than being consumed through use, and (3) it can be shared only, not exchanged in transactions. At the same time, information is compressible, both syntactically and semantically. Coupled with its ability to be substituted for other economic resources, its transportability at very high speeds, and its ability to impart advantages to the holder of information, these characteristics are at the base of such societal industries as research, education, publishing, marketing, and even politics. Societal concern with the husbanding of information resources has extended from the traditional domain of libraries and archives to encompass organizational, institutional, and governmental information under the umbrella of information resource management.

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The second perception of information is that it is an economic commodity, which helps to stimulate the worldwide growth of a new segment of national economies—the information service sector. Taking advantage of the properties of information and building on the perception of its individual and societal utility and value, this sector provides a broad range of information products and services. By 1992 the market share of the U.S. information service sector had grown to about $25 billion. This was equivalent to about one-seventh of the country’s computer market, which, in turn, represented roughly 40 percent of the global market in computers in that year. However, the probable convergence of computers and television (which constitutes a market share 100 times larger than computers) and its impact on information services, entertainment, and education are likely to restructure the respective market shares of the information industry.

Elements of information processing
Humans receive information with their senses: sounds through hearing; images and text through sight; shape, temperature, and affection through touch; and odours through smell. To interpret the signals received from the senses, humans have developed and learned complex systems of languages consisting of “alphabets” of symbols and stimuli and the associated rules of usage. This has enabled them to recognize the objects they see, understand the messages they read or hear, and comprehend the signs received through the tactile and olfactory senses.

The carriers of information-conveying signs received by the senses are energy phenomena—audio waves, light waves, and chemical and electrochemical stimuli. In engineering parlance, humans are receptors of analog signals; and, by a somewhat loose convention, the messages conveyed via these carriers are called analog-form information, or simply analog information. Until the development of the digital computer, cognitive information was stored and processed only in analog form, basically through the technologies of printing, photography, and telephony.

Although humans are adept at processing information stored in their memories, analog information stored external to the mind is not processed easily. Modern information technology greatly facilitates the manipulation of externally stored information as a result of its representation as digital signals—i.e., as the presence or absence of energy (electricity, light, or magnetism). Information represented digitally in two-state, or binary, form is often referred to as digital information. Modern information systems are characterized by extensive metamorphoses of analog and digital information. With respect to information storage and communication, the transition from analog to digital information is so pervasive as to bring a historic transformation of the manner in which humans create, access, and use information.

Acquisition and recording of information in analog form
The principal categories of information sources useful in modern information systems are text, video, and voice. One of the first ways in which prehistoric humans communicated was by sound; sounds represented concepts such as pleasure, anger, and fear, as well as objects of the surrounding environment, including food and tools. Sounds assumed their meaning by convention—namely, by the use to which they were consistently put. Combining parts of sound allowed representation of more complex concepts and gradually led to the development of speech and eventually to spoken “natural” languages.

For information to be communicated broadly, it needs to be stored external to human memory; because accumulation of human experience, knowledge, and learning would be severely limited without such storage, the development of writing systems was made necessary.

Civilization can be traced to the time when humans began to associate abstract shapes with concepts and with the sounds of speech that represented them. Early recorded representations were those of visually perceived objects and events, as, for example, the animals and activities depicted in Paleolithic cave drawings. The evolution of writing systems proceeded through the early development of pictographic languages, in which a symbol would represent an entire concept. Such symbols would go through many metamorphoses of shape in which the resemblance between each symbol and the object it stood for gradually disappeared, but its semantic meaning would become more precise. As the conceptual world of humans became larger, the symbols, called ideographs, grew in number. Modern Chinese, a present-day result of this evolutionary direction of a pictographic writing system, has upwards of 50,000 ideographs.

At some point in the evolution of written languages, the method of representation shifted from the pictographic to the phonetic: speech sounds began to be represented by an alphabet of graphic symbols. Combinations of a relatively small set of such symbols could stand for more complex concepts as words, phrases, and sentences. The invention of the written phonetic alphabet is thought to have taken place during the 2nd millennium BC. The pragmatic advantages of alphabetic writing systems over the pictographic became apparent twice in the past millennium: after the invention of the movable-type printing press in the 15th century and again with the development of information processing by electronic means since the mid-1940s.

From the time early humans learned to represent concepts symbolically, they used whatever materials were readily available in nature for recording. The Sumerian cuneiform, a wedge-shaped writing system, was impressed by a stylus into soft clay tablets, which were subsequently hardened by drying in the sun or the oven. The earliest Chinese writing, dating to the 2nd millennium BC, is preserved on animal bone and shell, while early writing in India was done on palm leaves and birch bark. Applications of technology yielded other materials for writing. The Chinese had recorded their pictographs on silk, using brushes made from animal hair, long before they invented paper. The Egyptians first wrote on cotton, but they began using papyrus sheets and rolls made from the fibrous lining of the papyrus plant during the 4th millennium BC. The reed brush and a palette of ink were the implements with which they wrote hieroglyphic script. Writing on parchment, a material that was superior to papyrus and was made from the prepared skins of animals, became commonplace about 200 BC, some 300 years after its first recorded use, and the quill pen replaced the reed brush. By the 4th century AD, parchment came to be the principal writing material in Europe.

Paper was invented in China at the beginning of the 2nd century AD, and for some 600 years its use was confined to East Asia. In AD 751 Arab and Chinese armies clashed at the Battle of Talas, near Samarkand; among the Chinese taken captive were some papermakers from whom the Arabs learned the techniques. From the 7th century on, paper became the dominant writing material of the Islamic world. Papermaking finally reached Spain and Sicily in the 12th century, and it took another three centuries before it was practiced in Germany.

With the invention of printing from movable type, typesetting became the standard method of creating copy. Typesetting was an entirely manual operation until the adoption of a typewriter-like keyboard in the 19th century. In fact, it was the typewriter that mechanized the process of recording original text. Although the typewriter was invented during the early 18th century in England, the first practical version, constructed by the American inventor Christopher Latham Sholes, did not appear until 1867. The mechanical typewriter finally found wide use after World War I. Today its electronic variant, the computer video terminal, is used pervasively to record original text.

Recording of original nontextual (image) information was a manual process until the development of photography during the early decades of the 19th century; drawing and carving were the principal early means of recording graphics. Other techniques were developed alongside printing—for example, etching in stone and metal. The invention of film and the photographic process added a new dimension to information acquisition: for the first time, complex visual images of the real world could be captured accurately. Photography provided a method of storing information in less space and more accurately than was previously possible with narrative information.

During the 20th century, versatile electromagnetic media opened up new possibilities for capturing original analog information. Magnetic audio tape is used to capture speech and music, and magnetic videotape provides a low-cost medium for recording analog voice and video signals directly and simultaneously. Magnetic technology has other uses in the direct recording of analog information, including alphanumerics. Magnetic characters, bar codes, and special marks are printed on checks, labels, and forms for subsequent sensing by magnetic or optical readers and conversion to digital form. Banks, educational institutions, and the retail industry rely heavily on this technology. Nonetheless, paper and film continue to be the dominant media for direct storage of textual and visual information in analog form.