A big band is a type of musical ensemble associated with playing jazz music and which became popular during the Swing Era from 1935 until the late 1940s. A big band typically consists of approximately 12 to 19 musicians and contains saxophones, trumpets, trombones, and a rhythm section. The terms jazz band, stage band, jazz orchestra, and dance band are also used to refer to this type of ensemble.

In contrast to smaller jazz combos, in which most of the music is improvised, or created spontaneously, music played by big bands is highly 'arranged', or prepared in advance and notated on sheet music. Improvised solos may be played only when called for by the arranger.