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:

“*Bit* by *bit* ... she had claimed herself. Freeing yourself was one thing; claiming ownership of that freed self was another.”

—Toni Morrison (b. 1931)

“Assumptions of male superiority are as widespread and deep rooted and every *bit* as crippling to the woman as the assumptions of white supremacy are to the Negro.... this is no more a man’s world than it is a white world.”

—Student Non-Violent Coordinating Committee, African American civil rights organization. SNCC Position Paper (Women in the Movement)

“Henry David Thoreau, who never earned much of a living or sustained a relationship with any woman that wasn’t brotherly—who lived mostly under his parents’ roof ... who advocated one day’s work and six days “off” as the weekly round and was considered a *bit* of a fool in his hometown ... is probably the American writer who tells us best how to live comfortably with our most constant companion, ourselves.”

—Edward Hoagland (b. 1932)