Cool jazz

"Even before the close of the 1940s, a reaction against the bop ethos could be heard on both the East Coast and West Coast. In time, this movement got a name -- "cool jazz.""

"Birth of the Cool, recorded in 1949 but released under that title in 1957, took jazz in a sharply different direction than bebop. As the title suggests, the original 78s of this session were the birth of “cool jazz,” although Miles ceeded the genre and much of the credit for creating it to Chet Baker and Gerry Mulligan because he spent the four years after its recording addicted to heroin."