A paratrooper is a military parachutist—someone trained to parachute into a military operation, and usually functioning as part of airborne forces. Military parachutists (troops) and parachutes were first used on a large scale during World War II for troop distribution and transportation. Paratroopers are often used in surprise attacks, to seize strategic objectives such as airfields or bridges.

Parachuting and skydiving is a method of transiting from a high point in an atmosphere to the ground or ocean surface with the aid of gravity, involving the control of speed during the descent using a parachute or parachutes.