The timpani or kettledrums are musical instruments in the percussion family. A type of drum categorised as a hemispherical drum, they consist of a membrane called a head stretched over a large bowl traditionally made of copper. Thus, timpani are an example of kettledrums, also known as vessel drums and semispherical drums, whose body is similar to a section of a sphere whose cut conforms the head. Most modern timpani are pedal timpani and can be tuned quickly and accurately to specific pitches by skilled players through the use of a movable foot-pedal. They are played by striking the head with a specialized beater called a timpani stick or timpani mallet. Timpani evolved from military drums to become a staple of the classical orchestra by the last third of the 18th century. Today, they are used in many types of ensembles, including concert bands, marching bands, orchestras, and even in some rock bands.