Bit

A bit, short for binary digit, is the basic unit of information in computing and digital communications. It has a binary value of either 0 or 1 and represents a choice between two distinct states. In information theory, a bit measures the amount of information needed to distinguish between two equally likely possibilities, quantifying uncertainty and information content.

A group of eight bits forms a byte, which is the standard unit used to express storage and data size in many computer systems. Data transfer rates are typically expressed in bits per second (bps), while storage is described in bytes and their multiples. To avoid ambiguity, binary prefixes such as kibibit (Kibit) and mebibit (Mibit) are used for bits, whereas decimal prefixes like kilobit (kbit) and megabit (Mbit) are common in networking with decimal values.

Historically, the term bit was coined by John Tukey in 1947 as a contraction of binary digit, and its central role in information theory was popularized by Claude E. Shannon in 1948. The bit underpins modern digital technology, governing how information is encoded, transmitted, and processed.

Bits are manipulated by digital logic and stored in memory as sequences that encode numbers, characters, instructions, and multimedia. They enable error detection and correction, data compression, encryption, and various encoding schemes. In practice, the practical choice between bits and bytes depends on context: hardware and networks often use bits, while software and storage use bytes and higher-order units.