Miles Davis was an American jazz trumpeter, bandleader, and composer who was widely regarded as one of the most influential musicians of the 20th century. He is particularly known for developing a new style of jazz known as "Cool Jazz" or "West Coast Jazz."
Cool Jazz emerged in the mid-to-late 1940s and was characterized by its relaxed tempos, soft dynamics, and an overall more relaxed and restrained approach to playing jazz compared to the more energetic and frenetic bebop style that preceded it. This new style was heavily influenced by classical music, particularly the works of composers such as Stravinsky and Debussy, and sought to create a more contemplative and introspective atmosphere in jazz music.
Davis played a major role in the development of Cool Jazz, both as a performer and a bandleader. He was part of a group of musicians based in New York City who were pushing the boundaries of jazz in new and exciting directions, and his cool and understated approach to playing the trumpet was a major influence on the sound of the genre. He also brought in elements of R&B and blues into his music, further expanding the boundaries of jazz and creating a unique sound that was all his own.
Davis' first major recording as a bandleader was the album "Birth of the Cool" in 1949, which was a collection of recordings made over several sessions in the late 1940s and is widely regarded as a seminal album in the development of Cool Jazz. The album featured a nonet of musicians, including Gerry Mulligan on baritone saxophone and Lee Konitz on alto saxophone, and showcased the relaxed and introspective sound of the genre.
Cool Jazz was a major departure from the more energetic and virtuosic bebop style that preceded it, and was seen by many as a reaction to the increasingly complex and virtuosic playing that had become the norm in jazz. By slowing down the tempos and focusing on more subtle and nuanced playing, Cool Jazz created a new space for jazz musicians to explore and express themselves in a more introspective and contemplative way.
In conclusion, Miles Davis was a major figure in the development of Cool Jazz, a new style of jazz that emerged in the mid-to-late 1940s and was characterized by its relaxed tempos, soft dynamics, and introspective atmosphere. Through his recordings and performances, Davis helped to establish Cool Jazz as a distinct and influential genre within the world of jazz, and his contributions to the genre continue to be celebrated and studied to this day. (Source: "Miles Davis and the Birth of the Cool" by Ted Gioia)