The drum is a member of the percussion group of music instruments, technically classified as the membranous. 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 drumstick, to produce sound. Drums are the world's oldest and most ubiquitous musical instruments, and the basic design has remained virtually unchanged for thousands of years.A few types of drums such as timpani are always tuned to a certain pitch. Often, several drums are arranged together to create a drum kit.