A pressure suit is a protective suit worn by high-altitude pilots who may fly at altitudes where the air pressure is too low for an unprotected person to survive, even when breathing pure oxygen at positive pressure. Such suits may be either full-pressure or partial-pressure. Partial-pressure suits work by providing mechanical counter-pressure to assist breathing at altitude.

A space suit or spacesuit is a garment worn to keep a human alive in the harsh environment of outer space, vacuum and temperature extremes. Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, and are necessary for extravehicular activity (EVA), work done outside spacecraft. Space suits have been worn for such work in Earth orbit, on the surface of the Moon, and en route back to Earth from the Moon. Modern space suits augment the basic pressure garment with a complex system of equipment and environmental systems designed to keep the wearer comfortable, and to minimize the effort required to bend the limbs, resisting a soft pressure garment's natural tendency to stiffen against the vacuum. A self-contained oxygen supply and environmental control system is frequently employed to allow complete freedom of movement, independent of the spacecraft.