digital system uses discrete (that is, discontinuous) values to represent information for input, processing, transmission, storage, etc. By contrast, non-digital (or analog) 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.
The word digital comes from the same source as the word digit and digitus (the Latin word for finger), as fingers are used for discrete counting.
The word digital is most commonly used in computing and electronics, especially where real-world information is converted to binary numeric form as in digital audio and digital photography. Such data-carrying signals carry electronic or optical pulses, the amplitude of each of which represents a logical 1 (pulse present and/or high) or a logical 0 (pulse absent and/or low).