In the 1980s, Japan made it illegal to own a firearm, though there was a large interest in them. Because of this interest, manufacturers started to produce spring-powered replicas of real guns. These guns fired several calibers of plastic or rubber BBs, but were eventually standardized into 6mm and 8mm sizes. The early spring powered weapons then morphed into gas and battery powered ones, using a variety of systems. The hobby then migrated to North America in the mid 1990s. This is due in large part to the addition of many new AEG (Automatic Electric Gun) manufacturers in Japan, Hong Kong, Taiwan, as well as many others.

Airsoft has also been adopted for training purposes for both military and police units (more often police units). Systema, a high end professional airsoft manufacturer, produces guns specifically designed for this purpose and are a 1:1 scale in every aspect of their real steel counterparts.

Military Simulation

"MilSim", short for Military Simulation, generally combines airsoft play with some military live-action role-playing elements. This type of play may be considered "hard core" by many players because of the heightened amount of roleplaying required. Several goals or missions may be assigned to each team, along with a basic load-out (i.e., supply) of ammunition, rations and radios.

A key element in Military Simulation games is the use of low-capacity magazines, replicating the actual magazine capacity of the authentic firearm the airsoft gun is replicating. Examples of these include the 30 round STANAG magazines of the M4, M16, Type 89, SCAR-L and several others.

Teams will remain in the field for the duration of play, only returning to a staging area or "safe zone" for medical emergencies and for other special circumstances. Military simulation games often last several days. For example, the large Berget annual event in Sweden lasts for six days with no breaks. In large scale Military Simulation operations, the players often use vehicles such as painted vans and trucks. In some cases, such as Operation Irene (an annual Military Simulation held in the Midwest U.S.), real APCs and tanks are used. Such large scale events can take place in MOUT (Military Operations in Urban Terrain) facilities.

True Military Simulation requires players to adhere to an agreed level of uniform authenticity and to play as part of a team.

Eye and face protection

The minimum safe level of gear required to participate in most games includes a pair of impact-rated goggles or shooting glasses to protect participants' eyes. Traditional prescription glasses and sunglasses, or goggles not designed specifically for use with airsoft or paintball guns may break or shatter upon being struck, causing damage to the eye.

Many airsoft groups and fields require that eye protection fully seals the area around the eyes, and also meets or exceeds ANSI's Z87.1-2003 goggle standard for eye protection, namely, the ability to absorb 3 joules of impact energy without damage. Some players instead opt for paintball goggles, which are held to a higher impact rating standard, ASTM's F1776.

Full-face masks (similar to, and often including paintball masks) are considered the safest form of eye-protection, as alongside the eyes, they also cover the rest of the face, protecting vulnerable parts such as teeth. Some airsoft masks are made with mesh screens, though there is debate that fragments from lower quality or bio-degradable BBs may pass through the mesh and enter the eye, although there have been no recorded incidents of such an occurrence. While masks offer superior protection, they can interfere with the use of scopes and in cheaper masks, condensation inside the goggles can reduce visibility. During very hot days the masks can also cause the player to overheat quicker due to the lack of air getting to the head.

Airsoft guns

The guns used in airsoft are typically replicas of real firearms, except that they have a mechanism for pushing out projectiles 6 mm or 8 mm in diameter.

Airsoft guns are classified according to their operating principle which can be spring, electric, or gas-powered. An airsoft gun is selected according to the level of performance (battery life, range, rate of fire, accuracy, reliability, customization, magazine capacity, size, and weight) or realism the player requires. Early-generation airsoft guns were mostly "springers." Single action airsoft guns fire only a single bb before having to be manually re-cocked for the next shot. Second-generation airsoft guns had gas-powered mechanisms that required either an internal "Flon" (CFC) gas reservoir or an external high-pressure CO2 chamber. AEGs (Automatic Electric Guns) are now the most commonly used. AEGs have high-capacity rechargeable batteries used to operate gearboxes that displace air and propel the BBs. However, gas powered long guns are becoming increasingly popular, as the increased realism of these guns are now more accessible due to their increasing quality.

Most airsoft pistols which are gas-powered use environmentally safe "green gas". Green gas is propane gas with small amounts of perfume and silicon lubricant that produces a realistic blowback recoil effect when fired. Recently Airsoft manufacturers have begun producing propane adapters that screw directly onto camping grade propane tanks, allowing players to power their gas guns on pure propane, as a cheaper alternative to "green gas". Each pistol magazine contains a small storage gas cylinder with enough power to propel the 30+ BB projectiles also housed in the magazine. Thus a player can realistically load, fire, and unload an airsoft pistol in a similar manner as compared to a "real steel" semi-automatic pistol. A few early-production AEPs (Airsoft Electric Pistols) have been released but these suffer from weaker BB velocities because of the difficulty of fitting a small-enough motor in the housing of a pistol, although the range is sometimes greater than a gas pistol. AEP's often have a higher rate of fire than their gas counterparts.

Most early airsoft guns were completely made of ABS plastic except for some internal moving parts. Newer guns, especially those made in Taiwan and China, have metal internal and external parts. Japan has specific rules about producing airsoft replicas with metal parts. A typical airsoft gun is noticeably lighter than its "real steel" counterpart due to the use of aluminium, alloy, and plastic, though some have weights in them for a more realistic feel. Smoke caps are available for certain airsoft guns to add realism.

Gas hand gun magazines are usually 10-20 in a standard capacity magazine, however some are hi cap magazines which have a winder and can hold 50 rounds or more. In the case of AEG rifles magazines come in either real-capacity (equivalent to the capacity of its real steel counterpart), low-capacity (low caps: 30-80 BBs), mid-capacity (mid caps: 80-150 BBs), or high-capacity (high caps: 200-500+ BBs). These magazines are spring loaded; the high-cap magazines often have a ratchet wheel that can be wound up periodically to force BBs up from the holding chamber of the magazine to the feed chute, due to loose BBs in the reservoir they often make a rattling noise when running or walking. Some airsoft guns have an electric-powered box or drum magazines that hold thousands of BBs (up to 5000).