This is a wind instrument that consists of two or more single- or double-reed pipes. The reeds are vibrated by wind caused by arm pressure on a skin or cloth bag. The pipes are held in wooden sockets tied into the bag, which is inflated either by the mouth or by bellows strapped to the body. Melodies are played on the finger holes of the melody pipe, or chanter, while the remaining pipes, or drones, sound single notes. Bagpipes existed by c. 100 ce. The early bag was an animal bladder or a nearly whole sheepskin or goatskin. Bagpipes have always been folk instruments. An important related instrument is the Irish union (or uilleann) pipes.