An idiophone is any musical instrument that creates sound primarily by the vibration of the instrument itself, without the use of air flow (as is the case with aerophones), strings (chordophones), membranes (membranophones) or electricity (electrophones). It is the first of the four main divisions in the original Hornbostel-Sachs scheme 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, triangle or marimba) or indirectly, by way of a scraping or shaking motion (like maracas or flexatone). Various types of bells fall into both categories. A common plucked idiophone is the Jew's harp.
Most percussion instruments that are not drums are idiophones. Hornbostel-Sachs divides idiophones into four main sub-categories. The first division is the struck idiophones (also known sometimes as concussion idiophones). This includes most of the non-drum percussion instruments familiar in the West. They include all idiophones made to vibrate by being struck, either directly with a stick or hand (like the wood block, singing bowl, steel tongue drum, triangle or marimba) or indirectly, by way of a scraping or shaking motion (like maracas or flexatone). Various types of bells fall into both categories.
The other three subdivisions are rarer. They are plucked idiophones, such as the Jew's harp, amplified cactus, kouxian, dan moi, music box and mbira (lamellophone or thumb piano); blown idiophones, of which there are a very small number of examples, the Aeolsklavier being one; and friction idiophones, such as the singing bowl, glass harmonica, glass harp, turntable, verrophone, daxophone, styrophone, musical saw, and nail violin (a number of pieces of metal or wood rubbed with a bow).
Other classifications use six main sub-categories.
Idiophones are made of materials that give off unique sounds. The majority of idiophones are made out of glass, metal, ceramics, and wood. Idiophones are considered part of the percussion section in an orchestra.