Ammunition is an object propelled by a projectile weapon such a gun or a bow. Whereas the weapon itself can be used over and over again, the supply of ammunition constantly needs to be replenished or the weapon becomes useless, except perhaps as a deterrent or show of force. In a more loose sense of the term, it can be used to refer to anything being thrown, shot, or otherwise projected towards a target. It is colloquially referred to as "ammo", and most commonly spoken of in the context of a war, the ammunition usually being bullets, grenades, rockets and other modern projectiles.