Drums have been used around the world since prehistoric times and appear in all shapes and sizes. Known as membranophones, drums make a sound when the stretched membrane is struck with an object, such as a rounded stick or the tips of the fingers. When the membrane is struck it vibrates and produces a sound. Some drums have pegs that can be adjusted to loosen or tighten the membrane, which changes the pitch and quality of the sound. There are many types of drums, such as bongos that are played with the hands and the Irish bodhran that is played with a double-ended beater. The drum kit shown here is typically used in popular and rock music.