A weapon, sometimes also called arm or armament, is a tool or object used to inflict damage on objects or living things. Some tools, such as the scythe, are not a weapon as only function but are originally or also used in an entirely different context. On the other hand, some weapons are also never used to inflict damage but serve as an ornament (e.g. ceremonial swords) or are carried around as a precaution (firearms of police]]. In the latter case, the weapon function may still at any time be used when the owner for instance regards himself in danger.

There are many types of weapons. A weapon can be short-distance (dagger, katana) or long-range (gun), high-tech (flamethrower, lightsaber) or just made of steel, wood or stone (falx, bow).