A capo is a device used on stringed instruments, such as guitars, to change the pitch of the strings. It is typically a clamp that attaches to the neck of the instrument, allowing musicians to play in different keys without changing finger positions. This makes it easier to play along with other instruments or singers. Capos come in various designs, including spring-loaded and adjustable types, and are popular among guitarists in many music genres. They are especially useful for songwriters who want to experiment with different sounds or for performers who need to match their vocal range.