Infantry is an army specialization whose personnel engage in military combat on foot, distinguished from cavalry, artillery, and armored forces. Also known as foot soldiers, infantrymen or infanteer, infantry traditionally rely on traveling by foot between combats as well, but may also use mounts (mounted infantry), military vehicles (motorized, and mechanized infantry), watercraft (naval infantry), or aircraft (airborne infantry) for between-combat mobility and logistics. Infantry make up a large portion of all armed forces in most nations, and typically bear the largest brunt in warfare, as measured by casualties, discomfort, fatigue, and both physical and psychological stress.