Science  People  Locations  Timeline
Index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Home > Information


 Contents
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.

Although many people speak of the advent of the "information age," the "information society," and information technologies, and even though 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 come to acquire.

The following is a list of the most important meanings, roughly in order of narrowest to broadest.

1 Information as a message

Information is a message, something to be communicated from the sender to the receiver, as opposed to noise, which is something that inhibits the flow of communication or creates misunderstanding. If information is viewed merely as a message, it does not have to be accurate. It may be a lie, or just a sound of a kiss. This model assumes a sender and a receiver, and does not attach any significance to the idea that information is something that can be extracted from an environment, e.g., through observation or measurement. Information in this sense is simply any message the sender chooses to create.

1.1 Measuring information

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 messages, then the preferred measure of "the information produced when one message is chosen from the set" is the base two logarithmIn mathematics, the logarithm functions are the inverses of the exponential functions. Logarithms are numbers that are substituted in computation for other numbers, to which they bear such a relation that the operations to be performed on the latter are r of . In this paper, Shannon continues:

The choice of a logarithmic base corresponds to the choice of a unit for measuring information. If the base 2 is used the resulting units may be called binary digits, or more briefly bitThis article is about the unit of information, see Bit (disambiguation) for other meanings. A bit (abbreviated b is the most basic information unit used in computing and information theory. A single bit (short for b inary dig it is a zero or a one, or a ts, a word suggested by J. W. TukeyJohn Wilder Tukey ( June 16, 1915 July 26, 2000) was a statistician. Born New Bedford, Massachusetts, Tukey obtained a Bachelor of Science degree in 1936 and a Master of Science degree in chemistry in 1937 from Brown University before moving to Princeton. 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 ... [The Bell System Technical Journal, Vol. 27, p. 379, (July 1948).]

Also see: self-informationWithin the context of information theory, self-information is defined as the amount of information that knowledge about (the outcome of) a certain event, adds to someone's overall knowledge. The amount of self-information is expressed in the unit of infor, lexicographic information costLexicographic information cost is a new concept within the field of lexicography. The term refers to the difficulties and inconveniences that the user of a dictionary believes or feels are associated with consulting a particular dictionary or dictionary a



Read more »

Non User