The pipe organ is a musical instrument that produces sound by driving pressurized air (called wind) through organ pipes selected via a keyboard. Because each pipe produces a single pitch, the pipes are provided in sets called ranks, each of which has a common timbre and volume throughout the keyboard compass. Most organs have multiple ranks of pipes of differing timbre, pitch, and volume that the player can employ singly or in combination through the use of controls called stops.
The organ is one of the oldest instruments still used in European classical music that has commonly been credited as having derived from Greece. Its earliest predecessors were built in Ancient Greece in the 3rd century BC. The word organ is derived from the Greek όργανον (organon), a generic term for an instrument or a tool, via the Latin organum, an instrument similar to a portative organ used in ancient Roman circus games.