bit
loreprogramming
Stands for: binary digit
The smallest unit of information, a single choice between 0 and 1, and the atom on which the entire digital world is built.
The word is a contraction of 'binary digit', coined by John Tukey in a Bell Labs memo dated January 9, 1947. His colleague Claude Shannon gave it its enduring meaning in 'A Mathematical Theory of Communication' (1948), the paper that founded information theory and was the first to put 'bit' in print, crediting Tukey. Shannon's insight was that any message, from text to a photograph to a song, could be measured and transmitted as a number of bits, decoupling information from whatever physical medium carries it. Everything downstream, bytes and files and protocols, follows from that one idea.
A bit is one binary digit, the smallest unit of information there is, and the word is a contraction of binary digit coined by John Tukey and popularized through Claude Shannon's 1948 work founding information theory. Shannon's insight was that information could be measured at all, and the bit is the unit of that measurement.
The operational point is that bits are the unit of transmission while bytes are the unit of storage, and the industry uses both with a one-letter difference between them. A hundred megabit connection delivers roughly twelve and a half megabytes per second before overhead, which is why a download appears eight times slower than the number the sales material quoted. That is not a swindle, it is two conventions colliding, and being able to convert instantly is basic professional literacy.
The other thing worth internalizing is that a bit is a decision. Each one halves the space of possibilities, which is why address lengths, key lengths and hash outputs are all discussed in bits, and why adding one bit to a key doubles the work of a brute-force attack. Reasoning in powers of two rather than in decimal is what makes those relationships obvious rather than something to be looked up.
Also known as: binary digit