What is bebop?

Bebop is a type of modern jazz that was popular between 1940 and 1955. Bebop musicians essentially added to the traditional 7-chord harmonies with improvised chords from the 12-note chromatic scale.
The stunning chord progressions were revolutionary for their time. Traditional jazz artists decried the destruction of the jazz form, but others praised the often abrupt melodic progressions in bebop. Because of its nontraditional melodic structure and rhythmic complexity, bebop was more suited to listening than dancing.
Important bebop performers of the time included Dizzy Gillespie, Charlie Parker, and Thelonious Monk. A bebop band was usually small, and the only music instruments were the trumpet, saxophone, drums, piano, and bass. Bebop musicians were such nonconformists; they modified Count Basie's popular rhythm section and came up with their own distinctive rhythms. For more, please refer to the links below.
https://www.britannica.com/art/bebop

https://www.jazzinamerica.org/JazzResources/StyleSheets/10