An organ trio, in a jazz context, is a group of three jazz musicians, typically consisting of a Hammond organ player, a drummer, and either a jazz guitarist or a saxophone player. In some cases the saxophonist will join a trio which consists of an organist, guitarist, and drummer, making it a quartet. Organ trios were a popular type of jazz ensemble for club and bar settings in the 1950s and 1960s, performing a blues-based style of jazz that incorporated elements of R&B. The organ trio format was characterized by long improvised solos and an exploration of different musical "moods".