Aleatoricism is the incorporation of chance into the process of creation, especially the creation of art or media. The word derives from the Latin word alea, the rolling of dice. "Aleatory" should not be confused with either improvisation or indeterminacy.
Charles Hartman discusses several methods of automatic generation of poetry in his book The Virtual Muse.
The term aleatory music was first coined by Werner Meyer-Eppler in 1955 to describe a course of sound events that is "determined in general but depends on chance in detail". When his article was published in English, the translator mistakenly rendered his German noun Aleatorik as an adjective, and so inadvertently created a new English word, "aleatoric".Pierre Boulez applied the term in this sense to his own pieces to distinguish them from the indeterminate music of John Cage. While Boulez purposefully composed his pieces to allow the performer certain liberties with regard to the sequencing and repetition of parts, Cage often composed through the application of chance operations without allowing the performer liberties. Another prolific composer of aleatory music was .
Aleatoric techniques are sometimes used in contemporary film music. Examples can be found in John Williams's scores as well as, for example, Mark Snow's music for X-Files: Fight the Future.
In film-making, there are several avant-garde examples; one is Andy Voda's Chance Chants which features Allison Knowles' computer poem "House of Dust",
Fred Camper's SN (1984, first screening 2002) uses coin-flipping for one section to determine which three of 16 possible reels to screen and what order they should go in (3360 permutations).
Film scholar Barry Salt directed the 1971 film Six Reels of Film to Be Shown in Any Order.