Cool jazz is a style and genre of modern jazz music inspired by bebop and big band that arose in the United States after World War II. It is characterized by relaxed tempos and a lighter tone than that used in the fast and complex bebop style. Cool jazz often employs formal arrangements and incorporates elements of classical music. Broadly, the genre refers to a number of post-war jazz styles employing a more subdued approach than that of contemporaneous jazz idioms. As Paul Tanner, Maurice Gerow, and David Megill suggest, "the tonal sonorities of these conservative players could be compared to pastel colors, while the solos of [Dizzy] Gillespie and his followers could be compared to fiery red colors."
The term cool started being applied to this music around 1953, when Capitol Records released the album Classics in Jazz: Cool and Quiet. Mark C. Gridley, writing in the All Music Guide to Jazz, identifies four overlapping sub-categories of cool jazz: