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A bit (abbreviated b) is the most basic information unit used in computing and information theory. A single bit (short for binary digit) is a zero or a one, or a true or a false, or for that matter any two mutually exclusive states.

A byte is a collection of bits, originally variable in size but now almost always eight bits. Eight-bit bytes are also known as octets. A four-bit quantity is known as a nibble. In some architectures, 16 bits make up a word, 32 bits a double word (dword): see word size.

Terms for large quantities of bits can be formed using the standard range of prefixes, e.g., kilobit (kbit), megabit (Mbit) and gigabit (Gbit). Note that much confusion exists regarding these units and their abbreviations, see Binary prefixes. Although it is clearer symbology to use "bit" for the bit and "b" for the byte, "b" is often used for bit and "B" for byte. (In SIThe International System of Units (symbol: SI (for the French phrase Systeme International d'Unites , is the most widely used system of units. It is used for everyday commerce in virtually every country of the world except the United States, and it is uni, B stands for the bel.)

The bit is the smallest unit of storage currently used in computing, although much research is ongoing in quantum computing with qubitA qubit is not to be confused with a cubit, which is an ancient measure of length. A qubit ( quantum + bit; pronounced /kyoobit/ [1 ) is a unit of quantum information. That information is described by state in a 2-level quantum mechanical system, whose tws.

See also

• Integral data type
• BitstreamA bitstream or bit stream is a time series of bits. A bytestream is a series of bytes, typically of 8 bits each, and can be regarded as a special case of a bitstream. Bitstreams are used extensively in telecommunications and computing: for example, the SD
• Information entropy
• Qubit