Bebop or bop is a form of jazz which uses a fast tempo and complex improvisational techniques. It was introduced in the 1940s.
Many bebop tunes were based on chord progressions (also called chord changes) from popular songs. The chord changes to the song "I Got Rhythm" by George Gershwin were so often used that they get their own name, "rhythm changes." Jazz solos had always been improvised over song chords, but entirely new compositions based on chord changes was an innovation.
The typical bebop combo consisted of bass, drums, and piano, with two horn players up front. The classic 1940s bebop combo was Charlie Parker on alto sax, Dizzy Gillespie on trumpet, Max Roach on drums, Percy Heath on bass, and Bud Powell on piano.
The name bebop (briefly called rebop) is an imitation of a characteristic quick two-note phrase that was played together by the lead instruments to introduce a solo or end a song.
Other notable musicians identified with bebop: