Topic summary
Quartets

Extracted from the Wikipedia article Quartet.
Jazz
Quartets are popular in jazz and jazz fusion music. Jazz quartet ensembles are often composed of a horn (eg., saxophone, trumpet, clarinet, cornet, etc.), a chordal instrument (e.g., piano, electric guitar, Hammond organ, vibraphone, etc.), a bass instrument (e.g., double bass, tuba or bass guitar) and a drum set. This configuration is sometimes modified by using a second horn replacing the chordal instrument, such as a trumpet and saxophone with string bass and drum kit, or by using two chordal instruments (e.g., piano and electric guitar).