Bit (Computing)

A bit, short for binary digit, is the smallest unit of information in computing, with only two possible values, 0 or 1. Bits are combined into larger units: eight bits make a byte, and data sizes are counted in kilobytes, megabytes and beyond, while network speeds are usually measured in bits per second, as described under bandwidth. Bits also measure cryptographic strength: a 256-bit private key, as used in Bitcoin, has $2^{256}$ possible values, far too many to guess, and the SHA-256 function produces a 256-bit output. Bits are the building blocks of binary code. The computing bit should not be confused with bits, a name sometimes used for one millionth of a bitcoin. Also see Bitstream.