Performers may choose to play in a certain style or key--though free music is far more often atonal--or at a certain tempo, but would be considered anomalous. Conventional songs are highly uncommon in free improvisation; there is generally more emphasis placed on mood, texture or, more simply, on performative gesture than on melody, harmony or predictable rhythm. These elements are improvised at will, as the music progresses.
Guitarist Derek Bailey has proposed non-idiomatic improvisation as a more accurately descriptive term, claiming the form offers musicians more possibilities "per cubic second" than any genre (Guitar Player, January 1997); while guitarist Elliott Sharp (himself occasionally active in one form or another of free improvisation) has argued--partly tongue in cheek--that no improvisation is ever truly free, excepting the unlikelyhood of amnesiac improvising musicians. (ibid)
Free music is a relatively little known, and somewhat loosely-defined genre, and none of its exponents can be said to be "famous" amongst the general public. However, in experimental circles, a number of free musicians are well known, including the aforementioned Derek Bailey, trombonist Conny Bauer, saxophonists Evan Parker and Peter Brötzmann, and guitarist Keith Rowe.
Perhaps the earliest free recordings are two songs by jazz pianist Lennie Tristano: "Intuition" and "Digression," both recorded in 1949 with a sextet including saxophone players Lee Konitz and Warne Marsh. Jazz critic Harvey Pekar has pointed out that one of Django Reinhardt's recorded improvisations strays drastically from the chord changes of the established piece. While noteworthy, these examples were clearly in the jazz idiom. A transitional period of in jazz the late 50s and early 60s instigated seemingly simultaneously by Cecil Taylor, Sun Ra, Ornette Coleman and Joe Maneri, allowed for radical improvised departures from the harmonic material of the composition. These ideas were extended in 1961's, Free Fall recording by jazz clarinetist Jimmy Giuffre's trio and culminated in New York Eye and Ear Control, a soundtrack for a film by Michael Snow recorded for the ESP-Disk label under the leadership of Albert Ayler. Snow suggested to Ayler that the band simply play without a composition or themes, and free improvisation, as a genre, was born.
In 1966 Elektra issued the first recording of European free improvisation by the UK group AMM, which included at the time Cornelius Cardew, Eddie Prevost, Lou Gare, Keith Rowe and Lawrence Sheaf. Through the remainder of the 60s and through the 70s, free improvisation spread across the U.S., Europe and East Asia, entering quickly into a dialogue with Fluxus, happenings and performance art (Cardew was associated with La Monte Young and other New York happenings artists) initially and making its influence immeadiately felt on rock and roll (Syd Barrett of Pink Floyd was famously an AMM devote; the Grateful Dead were noteworthy extensions of the influence).
John Stevens' Spontaneous Music Ensemble was also formed in the mid-60s and included, at various times, influential players such as Derek Bailey, Evan Parker, Kenny Wheeler, Trevor Watts, Roger Smith, and John Butcher. Musica Electronica Viva were formed in Rome in 1966 by Alvin Curran, Richard Teitelbaum, Frederic Rzewski, Allan Bryant, Carol Plantamura, Ivan Vandor, and Jon Phetteplace. Blurring the lines between free jazz and free improvisation, the the Chicago-based Association for the Advancement of Creative Musicians, a loose collective of improvising musicians and including Muhal Richad Abrams, Henry Threadgill, Anthony Braxton, Jack DeJohnette, Lester Bowie, Roscoe Mitchell, Joseph Jarman, Famadou Don Moye, and Malachi Favors was formed in 1965 and included many of the key players in the nascent international free improvisation scene. (Braxton recorded many times with Bailey and Teitelbaum; Mitchell recorded with Thomas Bruckner and Pauline Oliveros; etc.)
Free improvisation saw its full bloom in the mid-70s as Japanese players like saxophonist Karou Abe and guitarist Masayuki Takayanagi took the music to dazzling heights, the Los Angeles Free Music Society ran ahead with rambunctious glee through the ideals of free music, and in 1976 Derek Bailey founded Company Week a festival which lasted until 1994 and combined an ever-changing roster of improvisors who collaborated live. The spirit of Company survives in expanded form in the High Zero Festival of Improvised Music in Baltimore, Maryland which began in 1999 and which places improvising musicians who have never collaborated before in novel configurations for four days each year.
Free music performers come from a variety of backgrounds, and there is often considerable crossover with other genres. For example, acclaimed soundtrack composer Ennio Morricone was a member of the free improvisation group Nuova Consonanza. Rock musician Thurston Moore has released a number of free improvisation collaborations. And, vice-versa, many free music performers also record and perform other styles of music: Anthony Braxton has written opera, and John Zorn has written acclaimed orchestral pieces. Elements of noise rock, IDM, minimalism and electroacoustic music are not uncommon in free improvisation.
The London based independent radio station Resonance 104.4FM, founded by the London Musicians Collective, frequently broadcasts experimental and free improvised performance works. Chicago's Sound Experiment, WNUR 89.3 FM is another source for free improvised music on the radio.
Free music performers often emphasise extended technique.