Bit

A bit is the smallest unit of data. A single bit can have only one of two possible values. You might think of a bit as a light bulb. Programmers and engineers say it has only two states: on and off. 

Usually, a bit's two possible values are referred to as 1 (one) and 0 (zero). But sometimes you you'll see the possible values of a bit called True (1) and False (0), or On (1) and Off (0).

To store a larger range of data, eight bits are often combined to make one byte.