A laptop battle is a competitive event for an electronic musician to match their skills against others. Competition rules limit equipment to a laptop computer and an external pointing device (mouse). Some competitions allow external hardware, usually a single MIDI controller (this set-up is very similar to those used for live PA). There are typically three or four rounds, following a single elimination bracket or similar structure. Each round consists of a number of head-to-head matches between two randomly selected participants. Rules vary, but typically the competitors are allowed two to three minutes on stage to play their individual compositions. Stage presence is often a key element for judging, in addition to technical finesse and an ability to engage the audience.