Avant-jazz is a genre of music that combines elements of traditional jazz with avant-garde and experimental styles. It is characterized by its use of improvisation, extended techniques, and unconventional instrumentation. The genre was first developed in the 1950s and has since become a popular form of jazz. Avant-jazz musicians often draw from a variety of influences, including classical, rock, and world music. The genre is known for its unique sound and its ability to push the boundaries of traditional jazz.