Airsoft guns are sometimes classified as "toy guns," because they are not real and are 1:1 replicas of actual firearms, usually made of plastic or metal that propel plastic pellets known as BBs using compressed air. A BB may be a 5-8 mm round or spherical pellet weighing 110-600 milligrams. Though an airsoft gun may not be real, its design and functional mechanism can be very similar to its actual counterpart.

The history of "airsoft" originated in Japan during the mid-1970s, mainly because it was illegal to own firearms by private individuals. The popular sport spread quickly to China, Hong Kong, Korea, Taiwan and the Philippines chiefly because of firearm restrictions in these countries. The popularity of airsoft guns in the United States and Europe began in the mid-1990s.

There are three main types of airsoft guns - spring-powered, gas-powered, and electric powered (or automatic electric guns). In spring-powered guns, the spring is cocked by pulling back the slide or bolt before firing each shot. Pressurized gases like propane and HFC134a refrigerant are used to propel BBs by gas-powered guns. Automatic electric gun uses electrical power from an onboard battery to operate.

Airsoft gun pellets come in different shapes, sizes and weights. Most airsoft pellets are normally 6mm spherical plastics. There are also starch-based biodegradable, metal coated, graphite coated, and steel pellets. Airsoft pellets typically weigh from 0.12 to 0.43 g. Airsoft pellets may not damage the skin but are extremely dangerous to the eyes. Goggles or other protective gear must be worn all the time while playing this sport.