Some of the main areas of experimental music:
Early Electronic Music: After World War II, the military technology that was used for communications was made available to musicians, who used this technology for early experiments in electronic music. Pierre Henry and Pierre Schaeffer pioneered the genre of musique concrète, while Iannis Xenakis, Edgard Varèse, Steve Reich, Pauline Oliveros, Karlheinz Stockhausen, and many others went on to use electronics in new ways.
Systems/Generative Music: This music is in some ways related to earlier serial music, yet takes the parameterization of musical elements to its extreme. The best known composer in this are is Iannis Xenakis. He took probability theory, game theory, and countless other mathematical and architectural models and applied them to musical elements. With the advent of computers, many composers now compose algorithmic music with the aid of software such as MAX.
Chance/Aleatory Music: This music was pioneered by John Cage. While his earlier pieces explored new rhythmic, structural, and timbral realms with the use of "square root rhythm" and prepared piano, he moved on to chance operations with his seminal Music of Changes for piano (1951). In this piece, the sequence of musical elements was determined compositionally by flipping coins. Cage went on to continue using chance operations for the rest of his life, though after the early 1950s, he used the oracles of the I Ching. Other notable composers who have used chance and indeterminacy operations in their music: Karlheinz Stockhausen, Pierre Boulez, and many others.
Minimalist Music: Considered by many to have been started by Terry Riley with In C (1963), minimalism is characterized by usually diatonic harmony, a pulsing rhythm, and repetitive phrasing. Often these materials are subjected to musical processes, such as phasing. Other notable composers in this genre are Steve Reich, Philip Glass, La Monte Young, and Gavin Bryars.
Conceptual/Transcendental Music: This area of experimental music is, by definition, hard to classify, because the music in the genre is often combined with conceptual art, and transcends genre-based distinctions. Influenced by the minimalists, aleatory composers, and conceptual art movements such as Fluxus, this music is often represented through text-based or graphical scores, and sometimes includes improvisation. Composers in this group include La Monte Young, Pauline Oliveros, and Cornelius Cardew.
Improvisation: Experimental improvisors often fuse noise, traditional musics, and jazz . Notable experimental improvisors include Pauline Oliveros and the Deep Listening Band, Anthony Braxton, Cecil Taylor, Cornelius Cardew and AMM, and Fred Frith.
New experimental music continues to be made every day. Current musicians such as Diamanda Galas, Laurie Anderson, Ikue Mori, John Zorn, Kaffe Matthews, and others push boundaries and genres. Indeed, this new music is so new that there have yet to be classifications invented for much of it.