Data that has been created, transmitted, or stored as a string of signals coded as "1" (on) or "0" (off). Data in digital form (text, numbers, graphics, voice, video, etc.) can be stored and processed by computers and communicated at high speed over electronic networks with complete accuracy and reliability.

A digital system uses discrete values, usually but not always symbolized numerically to represent information for input, processing, transmission, storage, etc. By contrast, non-digital systems use a continuous range of values to represent information. Although digital representations are discrete, the information represented can be either discrete, such as numbers, letters or icons, or continuous, such as sounds, images, and other measurements of continuous systems.
Source: Wikipedia