Binary bit
A bit is a single binary character. it is either a zero or a one. This is because data is stored in a "yes/no" format. On a magnetic drive, a point it magnetized as north or south. If it is recorded as north, this means 0, if South, then 1. In all other cases, a pulse or change is a one. A lack of signal or change means a zero. Optical drives have the foil backing melted in points to make these ones--gaps are zeros. Flash memory uses physical switches, which are set to "yes" or "no" (one or zero) by electric impulses. As a computer works and "thinks," it sends pulses through it's various systems for ones, and pauses for zeros. [1]
Regardless of the storage method, there is always a one or a zero. For ease of use, bits are often grouped together by eights, into what is known as a byte.[2]