Short for binary digit, a bit is the smallest unit of data in a computer and is used for storing information. A bit is a binary unit, which means it can have a value of a 1 or a 0. A byte is a capacity unit that contains eight bits. To distinguish between the two, a “b” represents “bit” and a “B” represents “byte.” While a bit is generally used to measure the rate of data transfer (e.g., when discussing bandwidth; mbps, kbps, gbps, etc.), bytes are often used to describe data capacity (e.g., the size of hard drives). (Also, see byte, kilobit, megabit, gigabit and gigabyte.)