The idiophone category is the first of the families to complete the Hornbostel-Sachs Classification system of musical instruments. The early classification of VIctor-Charles Mahillon called this group “autophones”. Idiophones are any musical instrument that creates sound primarily by the vibration of the instrument its self. Unlike aerophones (wind instruments) this principle is achieved with out the requirement of an uninterrupted column of air flow. The most common are struck idiophones, or concussion idiophones. Which are made to vibrate when directly struck. Either directly like a wood, block, singing bowl or steel tongue drum, triangle or marimba. Or indirectly played by scraping or shaking motions like maracas or flexatone.