Jazz music moves off the dance floor.
The development of bebop in the 1940s is crucial to understanding jazz as we know it. A product of jam sessions, big bands, small combos, and countless hours of "woodshedding," the musical language of bebop included rapid tempos, dissonant chords and melodic lines, tritone and other chordal substitutions, extensive chromaticism, off-beat piano accompaniment ("comping"), walking bass lines, poly-rhythmic drumming, and, perhaps most important, a focus on extended, improvised soloing on the front-line instruments. Swing-era heavyweights such as Coleman Hawkins, Lester Young, Roy Eldridge, Art Tatum, Duke Ellington, Jimmy Blanton, and Walter Page had previously explored aspects of this language in the 1930s, but they came together in spectacular fashion in the work of Charlie Parker, John Birks "Dizzy" Gillespie, and Thelonious Monk, to name a handful of bebop's best-known practitioners. – Eric Porter "Dizzy Atmosphere": The Challenge of Bebop." American Music 17, no. 4 (1999)
The word bebop appeared in several jazz songs in the early 20th century, including "Four or Five Times" by McKinney's Cotton Pickers in 1928 and the novelty song "I'se a A-Muggin' " in 1936. There is some debate about how the term first came to describe a specific type of music. Dizzy Gillespie, Charlie Christian and Thelonious Monk have all been credited by different historians as the originator.