1940s
The swing era lasted until the mid-1940s, and produced popular tunes such as Duke Ellington's "Cotton Tail" (1940) and Billy Strayhorn's "Take the 'A' Train" (1941). With the big bands struggling to keep going during World War II, a shift was happening in jazz in favor of smaller groups. Some swing era musicians, like Louis Jordan, later found popularity in a new kind of music, called "rhythm and blues", that would evolve into rock and roll in the 1950s.
Bebop emerged in the early 1940s, with Charlie Parker, Dizzy Gillespie and Thelonious Monk leading the way. It appealed to a more specialized audiences than earlier forms of jazz, with sophisticated harmonies, fast tempos and often virtuoso musicianship. Bebop musicians often used 1930s standards, especially those from Broadway musicals, as part of their repertoire. Among standards written by bebop musicians are Gillespie's "Salt Peanuts" (1941) and "A Night in Tunisia" (1942), Parker's "Anthropology" (1946), "Yardbird Suite" (1946) and "Scrapple from the Apple" (1947), and Monk's "'Round Midnight" (1944), which is currently the most recorded jazz standard composed by a jazz musician.
Read more about this topic: Jazz Standard