The term trio in jazz usually refers to a group comprising a pianist, a double bass player and a drummer. The pianist is usually considered the leader of these trios, and trios are usually named after their pianist. Famous examples include the Bill Evans Trio with Scott LaFaro on bass and Paul Motian on drums. Art Tatum's trio substituted guitar for drums, and Nat King Cole's trio and Oscar Peterson's first famous trio followed suit. Later Oscar Peterson reverted to the traditional format of piano, bass, and drums. Another fairly common variant comprises electric organ (typically a Hammond B-3), drums, and electric guitar. No bass player is needed because the organist works his bass pedals.
