Bop is a three-letter up-tempo jazz genre that originated in the 1940s. It is characterized by fast tempos, improvisation, and complex harmonic structures. BOP was developed by jazz musicians such as Charlie Parker, Dizzy Gillespie, and Thelonious Monk, who sought to create a more modern sound than traditional jazz. BOP has been influential in the development of other jazz genres, such as hard BOP and free jazz.