A device, usually made from lightweight, strong cloth, that slows the movement of a body through air. Parachutes are used to allow crew to abandon a crippled aircraft safely, to deliver airborne troops to a battlefield, to deliver supplies and equipment to places where an aircraft could not land, to slow a vehicle moving horizontally, such as an aircraft on its landing run or a racing car, and for sport. Parachutes are circular or square, and may provide drag only, or allow air to enter between ribs to form cells that form the parachute into an aerofoil shape, providing lift and allowing its user greater control over the descent; such parachutes are known as ram-air parachutes.