The term 'CERTAIN JAZZ' refers to a style of jazz music known as bebop, or BOP for short. Bebop is a fast-paced, improvisational style of jazz that originated in the 1940s and 1950s. It is characterized by complex harmonic structures, fast tempos, and virtuosic solos. Bebop is often seen as a reaction to the more traditional swing style of jazz, and has had a lasting influence on the development of jazz music.