Bebop or bop is a style of jazz characterized by fast tempo, instrumental virtuosity, and improvisation based on the combination of harmonic structure and melody. It was developed in the early and mid-1940s. It first surfaced in musicians’ argot some time during the first two years of American involvement in the Second World War. This style of jazz ultimately became synonymous with modern jazz, as either category reached a certain final maturity in the 1960s.
