Most often it is bb guns that are used in Airsoft, but their muzzle velocity is reduced to half and pellets or bbs used are not metallic and are smaller in size. Airsoft and bb guns find their application in military training as well. Japan was the country that designed Airsoft first in 1970, America and some other countries found it very useful to military combats simulations. Airsoft games can vary a lot depending on the budget and composition of the team. Depends upon which park you get to play Airsoft in, you could be taught some military tactics to beat your opponent and furthermore may use uniform and protection gear that resembles military. Airsoft in all levels seem very interesting, be it kids or adults. Before the advent of bb guns people were using air guns that was meant for hunting. BB guns revolutionized the Airsoft as a game or a military simulation. BB guns and air guns have a major difference that Air spring used in bb guns makes it harmless. Manufacturers started creating exact copies of real weaponry in terms of form and function but used air spring that gives the required muzzle velocity to the pellets.
There is lot more that we may get to see in Airsoft and BB guns in coming times. We may see prototype jets being used in Airsoft that fly for real and have got firearms as well to shoot opponents. Technology will advance the level of thrill that used to give a great deal of excitement to kids and adults.