Small arms and light weapons

• "Small arms", broadly speaking, are individual-service (i.e. for carry and operation by individual infantrymen) kinetic projectile firearms. These include: handguns (revolvers, pistols, derringers, and machine pistols), muskets, rifled muskets, shotguns, rifles (assault rifles, battle rifles, carbines, designated marksman rifles, short-barreled rifles, sniper rifles, etc.), submachine guns, personal defense weapons, squad automatic weapons, and light machine guns.
• "Light weapons", broadly speaking, are infantry-portable weapons that are either crew-served kinetic firearms, incendiary devices, or shoot explosive munitions. These include: anti-materiel rifles, anti-tank rifles, general-purpose machine guns, medium machine guns, unmounted heavy machine guns, portable flamethrowers, grenades, rifle grenades, underslung grenade launchers, grenade launchers, automatic grenade launchers, recoilless rifles, rocket-propelled grenades, man-portable anti-tank system, man-portable air-defense systems, and mortars under 100 millimetres (3.9 in) caliber.

Small Arms and Light Weapons also include ammunition, explosives, hand grenades, land mines, and any other man portable weapons not listed above.

In contrast, the term "heavy weapons" generally refers to any other weapon systems that are too cumbersome for foot transportation and hence have to rely on fixed mounting platforms installed upon wheeled frames/vehicles, vessels, aircraft or fortifications for effective operation.

Definition by international legal conventions

According to the United Nations Office on Drugs and Crime, the international framework on firearms is composed of three main instruments: the Firearms Protocol, the United Nations Programme of Action to Prevent, Combat and Eradicate the Illicit Trade in Small Arms and Light Weapons in All Its Aspects (Programme of Action, or PoA) and the International Instrument to Enable States to Identify and Trace, in a Timely and Reliable Manner, Illicit Small Arms and Light Weapons (International Tracing Instrument, or ITI), where only the Firearms Protocol is legally binding.

The ITI, adopted by the United Nations General Assembly on 8 December 2005, defines small arms and light weapons as:

any man-portable lethal weapon that expels or launches, is designed to expel or launch, or may be readily converted to expel or launch a shot, bullet or projectile by the action of an explosive, excluding antique small arms and light weapons or their replicas. Antique small arms and light weapons and their replicas will be defined in accordance with domestic law. In no case will antique small arms and light weapons include those manufactured after 1899:

(a) "Small arms" are, broadly speaking, weapons designed for individual use. They include, inter alia, revolvers and self-loading pistols, rifles and carbines, sub-machine guns, assault rifles and light machine guns;

(b) "Light weapons" are, broadly speaking, weapons designed for use by two or three persons serving as a crew, although some may be carried and used by a single person. They include, inter alia, general purpose or universal machine guns, medium machine guns, heavy machine guns, rifle grenades, under-barrel grenade launchers and mounted grenade launchers, portable anti-aircraft guns, portable anti-tank guns, recoilless rifles, man portable launchers of anti-tank missile and rocket systems, man portable launchers of anti-aircraft missile systems, and mortars of a calibre of less than 100 millimetres.

Such arms control policies and treaties are focused on international arms trafficking (importation and export), and in the standardization of laws, protocols and sharing of law enforcement information and best practices across nations to prevent illicit arms sales. They also focus on terrorism, arms proliferation as a humanitarian concern, disarmament in the face of extreme violence, and cases of ameliorating anarchy, civil war and international conflict. SALW provisions are generally not oriented towards imposing or enforcing domestic national or local legislation of legitimate gun ownership or sale.