Serialism

Serialism is a rigid system of writing music in which various elements of the piece are ordered according to a pre-determined series, and variations on it. The elements thus controlled may be the pitch of the notes, their length, their dynamics, their accents, or virtually anything else.

Serialism is an extension of Arnold Schoenberg's twelve-tone technique (sometimes called dodecaphony), which involves the use of tone rows: the basis of the system is that the main theme of the composition consists of one (and only one) instance of each of the twelve notes in the chromatic scale. The terms serial and twelve tone are sometimes used as synonyms, though this is not strictly speaking correct.