A percussion instrument is a musical instrument that is sounded by being struck or scraped by a beater (including attached or enclosed beaters or rattles), or struck, scraped or rubbed by hand, or struck against another similar instrument. The percussion family is believed to include the oldest musical instruments.

The percussion section of an orchestra, however, traditionally contains in addition many instruments that are not, strictly speaking, percussion, such as whistles and sirens. On the other hand, keyboard instruments such as the celesta are not normally part of the percussion section, but keyboard percussion instruments (which do not have keyboards) are included.

Percussion instruments are most commonly divided into two classes: Tuned percussion instruments, which produce notes with an identifiable pitch, and untuned percussion instruments, which produce notes without an identifiable pitch.

Hornbostel–Sachs has no high-level section for percussion. Most percussion instruments (as the term is normally understood) are classified as idiophones and membranophones. However the term percussion is instead used at the lower levels of the Hornbostel–Sachs hierarchy, including to identify instruments struck either with a non-sonorous object (hand, stick, striker) or against a non-sonorous object (human body, the ground) as opposed to concussion which refers to instruments in which two or more complementary sonorous parts are struck against each other, and for other purposes. For example:

Dame Evelyn Elizabeth Ann Glennie,DBE (born 19 July 1965) is a Scottish virtuoso percussionist. She was the first full-time solo percussionist in 20th-century western society.

Glennie was born and raised in Aberdeenshire. Her father was Herbert Arthur Glennie, an accordionist in a Scottish country dance band, and the strong, indigenous musical traditions of north-east Scotland were important in the development of the young musician, whose first instruments were the mouth organ and the clarinet. Other major influences were Glenn Gould, Jacqueline du Pré and Trilok Gurtu. She studied at Ellon Academy and the Royal Academy of Music, and was also a member of the National Youth Orchestra of Scotland.

Glennie tours extensively in the northern hemisphere, spending up to four months each year in the United States, and performs with a wide variety of orchestras and contemporary musicians, giving over 100 concerts a year as well as master classes and "music in schools" performances;she frequently commissions percussion works from composers and performs them in her concert repertoire.

Jimmy Lopez (born 21 October 1978) is a classical music composer from Lima, Peru. He has won several international awards and pieces composed by him have been performed by the Chicago Symphony Orchestra, Fort Worth Symphony Orchestra, Baltimore Symphony Orchestra, Aspen Concert Orchestra, National Symphony Orchestra of Peru, and the Lima Philharmonic Orchestra. In 2000, he moved to Helsinki to study at the Sibelius Academy, and since 2004, has been a member of the Society of Finnish Composers.

In 1998, Lopez began studying at the National Conservatory of Music in Lima, where he worked with the Peruvian composer Enrique Iturriaga. He was admitted to the Sibelius Academy in 2000, and studied there with Veli-Matti Puumala and Eero Hämeenniemi. After being awarded a Master of Music degree, he was admitted to University of California, Berkeley where he is currently studying for a PhD in Composition. He has participated in masterclasses with Magnus Lindberg, Jouni Kaipainen, Michael Nyman and Marek Kopelent, among others.