a) A set of rules or processes for solving a problem in a finite number of steps. In audio, video, and data coding, the step-by-step procedure (often including repetition) which provides suitable compression and/or encryption for the specific application. When used for compression, this mathematical process results in a significant reduction in the number of bits required for transmission and may be either lossless or lossy.

b) Step-by-step procedure for the solution to a problem. First the problem is stated and then an algorithm is devised for its solution.