In broad sense the term encompasses twelve-tone technique and is referred to as a twelve-tone serialism. In a narrower sense serialism means that serial organization is extended to musical elements other than pitch (such as duration, dynamics, register, or articulation). 

This term popularized in Europe by Pierre Boulez means a musical result of actions made by chance ("alea" is Latin for "dice") or choice. The composers offered the players, for example, choices of route through the fragments of their work, allowed them to join these elements freely but, at the same time, they were completely responsible for the overall shape of the work. Aleatory music is sometimes treated as a synonym of indeterminate music (indeterminacy) but the latter term was preferred by John Cage and meant not only performance liberties but also the use of chance element in the process of composition. Although aleatoricism is an extremely different musical concept than serialism, the end result of both ideas may sound surprisingly alike.