A side arm is a firearm, usually a pistol, which is worn on the body in a holster to permit immediate access and use. A side arm is typically required equipment for law enforcement personnel and military personnel. Usually, uniformed personnel of these services wear their weapons openly, while plainclothes personnel have their side arms concealed under their clothes.
Government security service bodyguards for VIPs and heads of state who need a weapon that can be concealed under clothing may have a fully automatic machine pistol as a side arm. In a military setting, machine pistols are issued as personal defense sidearms to paratroopers, artillery crews, helicopter crews or tank crews.
