A sidearm is a small personal weapon that is typically worn on the body in a holster in such a way to permit immediate access and use. Although this term can apply to swords and other melee weapons, the modern use of it usually pertains to pistols and similar firearms.

A sidearm is typically required equipment for law enforcement personnel and military officers. Usually, uniformed personnel of these services wear their weapon openly, while plainclothes personnel typically keep them under their outer clothes. However in some military situations, military officers prefer not have such a weapon visible as it can identify them as a priority target for snipers.