The rhythm section of a jazz band consists of the percussion, double bass or bass guitar, and usually at least one instrument capable of playing chords, such as a piano, guitar, Hammond organ or vibes. Large early jazz bands such as Paul Whiteman’s employed two pianos, an accordion and banjo. The rhythm section is the foundation for the band; it sets the feel for the piece.
The horn section consists of wind and brass instruments, which play the melody and main accompaniment. Typical horns found in a big jazz band include 4 to 5 trumpets, saxophones (2-3 altos, 2 tenors, and a baritone), 3-4 trombones, and a bass trombone. The saxophones may also double on flute, clarinet,bass clarinet and soprano saxophone, the trumpets on flugelhorn, and the bass trombone on tuba.