Although most people have heard of jazz, and many recognize it when they hear it, the music is notoriously hard to categorize. There is simply no single description that can account for the vast number of styles and genres that have been placed under the jazz “umbrella.” In fact, some musicians (Duke Ellington, Randy Weston, and others) have avoided using the term altogether, finding the concept too confining. The term itself (and its variant “jass”) did not appear until the 1910s, after jazz was already a well-established idiom, and has been applied to many types of music that most purists would not consider “true” jazz at all, from the novelty piano rags of Zez Confrey in the 1920s to the instrumental pop music of Kenny G in the 1980s and 1990s.
A few general comments can be made about the music, however. We know, first of all, that jazz was a music created primarily by African Americans, and it has deep roots in traditions that go back as far as the African traditions brought by slaves to America during the Middle Passage. Related to this are two dualities that virtually all types of jazz share. These dualities create a vibrant tension in the music that gives jazz much of its power.