A drum is a musical instrument in the percussion group. It consists of a stretched membrane, the head or drumhead, attached to a shell called the barrel or body. Drumheads can be made from a variety of materials, including animal skin, synthetic materials, and metal. The shell can be made from a variety of materials, such as wood, metal, or ceramic. Drums are struck with the hands, beaters, mallets, or brushes to produce sound. Drums are classified into four broad categories: pitched percussion, such as the timpani; non-pitched percussion, such as the snare drum; electronic drums, including drum machines and electronic drum sets; and world percussion instruments such as hand drums. Drums occupy a prominent role in a wide variety of genres, including classical music, jazz, popular music, folk music, world music, and marching bands. Drums provide different types of beats, from fundamental rhythms to intricate solos. In many cultures, drums hold symbolic, cultural, and ritualistic significance beyond serving as musical instruments.