Projectile

A projectile is any object projected through the air by the application of some force. In a general sense, even a football or baseball may be considered a projectile, but in practical action most projectiles are designed as weapons. Arrows, darts[?], spears, and similar weapons are fired using pure mechanical force applied by another solid object; conversely, other weapons use the compression or expansion of gases as their motive force. Blowguns and pneumatic rifles used compressed gases, while most other guns and firearms utilize expanding gases liberated by sudden chemical reactions. Although blowguns use small darts, most types of guns and firearms hurl bullets, pellets, or shot made of a metal, usually lead, that are designed to deform and fragment inside a target, causing significant damage. Items like arrows, hand darts, and spears are generally tipped with sharp metallic or lithic artifacts called projectile points that allow them to more easily penetrate a target, although some types of arrows used for hunting are designed to stun or kill through shock rather than to penetrate.

Projectiles designed to be non-lethal, for example for use against riots, include rubber bullets and flexible baton rounds.

See bow (weapon), atlatl, and gunpowder.