A drum kit, drum set or trap set is a collection of drums and other percussion instruments set up to be played by a single player. Percussion instruments can be divided into three main categories: idiophones which when played give out their own natural sound, membranophones, which depend for their sound on a membrane stretched over a resonator, and chordophones, involving struck strings. The traditional drum kit is a collection including both idiophones and membranophones. More recently it has also included electronic instruments, with both hybrid and entirely electronic kits now in common use.