A pneumatic weapon is a weapon that fires a projectile by means of air pressure, similar in principle to the operation of pneumatic tube delivery systems. The term comes from a Greek word for "wind" or "breath" (πνεῦμα).
In theory, pneumatic weapons have certain advantages over traditional firearms:
On the other hand,
In practice, steam cannons and airguns were developed throughout 17th to 19th century, and the latter even in service with the Austrian army from 1780 to around 1815, but firearms kept the upper hand.
The low projectile speed requirement of a toy weapon greatly reduces the amount of air pressure needed; combined with the importance of safety in the toy industry, this has led to widespread adoption of pneumatic firing mechanisms in toy weapons, where a propellant reaction is not appropriate (although other technologies, such as rubber bands, can be used).
The toy industry has produced a number of pneumatic toy weapons, which fire small, lightweight (often plastic and frequently hollow) projectiles at relatively low speeds. Airsoft and paintball guns are a popular toy that operates this way; when used with adequate safety equipment (eye protection at a minimum) these may be used in games involving shooting at other players.
BB guns and other low powered air guns are often marketed towards the youth market. However, in many countries they are subject to normal firearms laws, or else a minimum age is imposed for possession and/or purchase. Such items can inflict lethal injuries if misused. In some countries minors may only use even low-powered airguns under the direct supervision of an adult. Gun safety rules should be followed when using air guns and BB guns.