Air ratchets, also referred to as pneumatic ratchet wrenches, operate via compressed air. Compressed air refers to air held or kept at a pressure greater than that of the atmosphere.
Air ratchets offer a square drive equal to other hand powered wrenches, but they are powered via an air motor. The air motor, which attaches to the socket drive and enables it to turn, converts compressed air to mechanical work via rotary or linear motion.
Mechanical work refers to energy that is transferred via a force that acts at a distance.
Air ratchets are often used in situations where speed is more desirable than torque. They are also frequently applied in small confined spaces, such as outboard motors and engine bays on cars.