A binary digit, or bit, is the smallest unit of information in a computer. It is used for storing information and has a value of true/false, or on/off. An individual bit has a value of either 0 or 1, which is generally used to store data and implement instructions in groups of bytes. A computer is often classified by the number of bits it can process at one time or by the number of bits in a memory address. Many systems use four eight-bit bytes to form a 32-bit word.