There are several overlapping schemes for the classification of percussion instruments. These schemes are based on four types of criteria: * The means by which the sound is produced. The most widely used classification system for musical instruments, Hornbostel–Sachs, takes this approach. * Musical usage, in particular the traditional division into tuned percussion and untuned percussion, and the similar and more modern division into pitched percussion and unpitched percussion. * The means of playing the instrument and skills required to play it, for example the grouping together of mallet percussion instruments, or of hand percussion instruments. This underlies the division of the orchestral percussion section into auxiliary percussion, tuned percussion and timpani, and is the reason p