A **bit** (a contraction of **binary digit**) is the basic capacity of information in computing and telecommunications; a bit can have the value of either 1 or 0 (one or zero) only. These attributes may be implemented, in a variety of systems, by means of a two state device.

In computing, a bit can be defined as a variable or computed quantity that can have only two possible values. These two values are often interpreted as binary digits and are usually denoted by the numerical digits 0 and 1. The two values can also be interpreted as logical values (*true*/*false*, *yes*/*no*), algebraic signs (*+*/*−*), activation states (*on*/*off*), or any other two-valued attribute. The correspondence between these values and the physical states of the underlying storage or device is a matter of convention, and different assignments may be used even within the same device or program. The length of a binary number may be referred to as its "bit-length".

In information theory, one bit is typically defined as the uncertainty of a binary random variable that is 0 or 1 with equal probability, or the information that is gained when the value of such a variable becomes known.

In quantum computing, a *quantum bit* or *qubit* is a quantum system that can exist in superposition of two bit values, "true" and "false".

The symbol for bit, as a unit of information, is either simply "bit" (recommended by the ISO/IEC standard 80000-13 (2008)) or lowercase "b" (recommended by the IEEE 1541 Standard (2002)).

Read more about Bit: History, Representation, Information Capacity and Information Compression, Multiple Bits, Bit-based Computing, Other Information Units

### Famous quotes containing the word bit:

“Roast Beef, Medium, is not only a food. It is a philosophy. Seated at Life’s Dining Table, with the menu of Morals before you, your eye wanders a *bit* over the entrées, the hors d’oeuvres, and the things à la though you know that Roast Beef, Medium, is safe and sane, and sure.”

—Edna Ferber (1887–1968)

“Perhaps he was a *bit* different from other people, but what really sympathetic person is not a little mad?”

—Isadora Duncan (1878–1927)

“The Lord made Adam, the Lord made Eve, he made ‘em both a little *bit* naive.”

—E.Y. Harburg (1898–1981)