The drum is a member of the percussion group of musical instruments. In the Hornbostel-Sachs classification system, it is a membranophone. Drums consist of at least one membrane, called a drumhead or drum skin, that is stretched over a shell and struck, either directly with the player's hands, or with a percussion mallet, to produce sound. There is usually a resonance head on the underside of the drum, typically tuned to a slightly lower pitch than the top drumhead.

 

Other techniques have been used to cause drums to make sound, such as the thumb roll. Drums are the world's oldest and most ubiquitous musical instruments, and the basic design has remained virtually unchanged for thousands of years. A number of different drums together with cymbals form the basic modern drum kit. Drums are usually played by striking with the hand, or with one or two sticks with or without padding. A wide variety of sticks are used, including wooden sticks and sticks with soft beaters of felt on the end. In jazz, some drummers use brushes for a smoother, quieter sound.