Percussion instruments are played by being struck or shaken. They are perhaps the oldest form of musical instruments. Some percussion instruments play not only rhythm, but also melody and harmony.

The two major categories are membranophones, which add timbre to the sound of being struck, such as drums, and idiophones, which sound of themselves, such as the triangle.

The tambourine is both membranophone and idiophone.

Most percussion instruments have a distinct tone; even drums are tuned. However, a distinction is usually made based on whether the instrument can play a definite pitch or not.

The timpani, xylophone, vibraphone, bell, tubular bells and glockenspiel all play a definite pitch. The snare drum, bass drum, cymbal, triangle, maracas, claves, castanets, tom-tom, timbales, cowbell, washboard and wood block do not in general. However, some percussionists tune drum heads to specific pitches when recording albums or in preparation for specific composer requirements. Gongs can be tuned or untuned – the most familiar type of gong in the west, the chau gong (sometimes called a tam-tam), is untuned. Tuned cymbals exist but are rare.

The general term for a musician who plays percussion instruments is percussionist. Drummer refers to a musician who primarily plays drums including the drumset and hand drums. A timpanist is a musician who primarily plays timpani. Marimbist generally refers to a solo artist who plays the marimba.

See 'drum' section for the list of drums.