An idiophone is any musical instrument that creates sound primarily by the vibration of the instrument itself, without the use of air flow (as with aerophones), strings (chordophones), membranes (membranophones) or electricity (electrophones). It is the first of the four main divisions in the original Hornbostel–Sachs system of musical instrument classification (see List of idiophones by Hornbostel–Sachs number). The early classification of Victor-Charles Mahillon called this group of instruments autophones. The most common are struck idiophones, or concussion idiophones, which are made to vibrate by being struck, either directly with a stick or hand (like the wood block, singing bowl, steel tongue drum, handpan, triangle or marimba) or indirectly, with scraping or shaking motions (like maracas or flexatone). Various types of bells fall into both categories. A common plucked idiophone is the Jew's harp.
According to Sachs, idiophones