Backline

Backline refers to the audio equipment behind the band on stage. Includes drums, percussion, guitar amps, bass amps, and keyboards/pianos. Some tours will travel with their own backline. When groups have to travel long distances or overseas, it is easier, and may be cheaper, for them to rent their backline locally.

Also been used to describe the line of curtains that is most upstage (i.e the furthest back line that the audience sees)