A membranophone is any musical instrument which produces sound primarily by way of a vibrating stretched membrane. It is one of the four main divisions of instruments in the original Hornbostel-Sachs scheme of musical instrument classification.
According to Sachs,
The sound is produced by a membrane ["skin" or "head"] stretched over an opening. Most, but not all, membranophones are generally called drums. They are classified according to material, if it's single or double headed, shape, skin(s), skin fastening, playing positions, and manner of playing.[1]