A digital system is a data technology that uses discrete (discontinuous) values. By contrast, non-digital (or Analog signal|analog) systems represent information using a continuous function. Although digital representations are Discrete mathematics|discrete, the information represented can be either discrete, such as numbers and Letter (alphabet)|letters or continuous, such as sounds, images, and other measurements.
The word digital comes from the same source as the words wikt:digit|digit and digitus (the Latin word for finger), as fingers are used for discrete counting. It is most commonly used in computing and electronics, especially where real-world information is converted to Binary numeral system|binary numeric form as in digital audio and digital photography.