Avant-Garde Jazz differs from free jazz in that it has more structure in the ensembles (more of a "game plan") although the individual improvisations are generally just as free of conventional rules. Obviously there is a lot of overlap between free jazz and avant-garde jazz; most players in one idiom often play in the other "style" too. In the best avant-garde performances it is difficult to tell when compositions end and improvisations begin; the goal is to have the solos be an outgrowth of the arrangement. As with free jazz, the avant-garde came of age in the 1960s and has continued almost unnoticed as a menacing force in the jazz underground, scorned by the mainstream that it influences. Among its founders in the mid-to-late '50s were pianist Cecil Taylor, altoist Ornette Coleman and keyboardist-bandleader Sun Ra. John Coltrane became the avant-garde's most popular (and influential) figure, and from the mid-'60s on, the avant-garde innovators made a major impact on jazz, helping to push the music beyond bebop.