Sequential algorithm

A sequential algorithm, also called a serial algorithm, is an algorithm that runs to completion in a single unbroken pass, from start to finish, with no other processing executing at the same time. The term exists to draw a contrast with concurrent algorithms and parallel algorithms: because most standard computer algorithms are written and executed sequentially, sequentialness is usually a background assumption that goes unstated, and the label is only applied when the contrast with concurrency or parallelism actually matters to the discussion. Concurrency and parallelism are themselves distinct concepts in computer science, though they frequently overlap in practice, since many distributed algorithms are both concurrent and parallel at once; because of this overlap, writers often use sequential loosely to contrast with either property without needing to specify which one is meant, and reach for the more precise pairing of sequential versus concurrent or serial versus parallel only when the distinction needs to be made explicit. Separately, the same phrase, sequential algorithm, is also used in a narrower technical sense in coding theory, where it names a specific class of algorithm for decoding a convolutional code.