Bit

The bit is the most basic unit of information in computing and digital communication. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented as 1 and 0, but other representations such as true/false, yes/no, on/off, and +/− are also widely used. The relation 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. It may be physically implemented with a two-state device. A contiguous group of binary digits is commonly called a bit string, a bit vector, or a single-dimensional (or multi-dimensional) bit array. A group of eight bits is called one byte, but historically, the size of the byte is not strictly defined. Frequently, half, full, double and quadruple words consist of a number of bytes which is a low power of two. A string of four bits is usually a nibble. In information theory, one bit is the information entropy of a random binary variable that is 0 or 1 with equal probability, or the information that is gained when the value of such a variable becomes known. As a unit of information, the bit is also known as a shannon, named after Claude E. Shannon. As a measure of the length of a digital string that is encoded as symbols over a binary alphabet (i.e. Σ = { 0 , 1 } {\displaystyle \Sigma =\{{\texttt {0}},{\texttt {1}}\}} ), the bit has been called a binit, but this usage is now rare. In data compression, the goal is to find a shorter representation for a string, so that it requires fewer bits when stored or transmitted; the string would be...