A firearm is a portable gun, being a barreled weapon that launches one or more projectiles often driven by the action of an explosive force. The first primitive firearms were invented in 13th century China when the man portable fire lance was combined with projectiles such as scrap metal, broken porcelain, or darts/arrows. The technology gradually spread through the rest of East Asia, South Asia, Middle East and then into Europe. In older firearms, the propellant was typically black powder, but modern firearms use smokeless powder or other propellants. Most modern firearms have rifled barrels to impart spin to the projectile for improved flight stability. Modern firearms are typically described by their bore diameter or calibre or gauge, the type of action employed together with the usual means of deportment. They may be further distinguished by reference to the type of barrel used and the barrel length, the design's primary intended target, or the commonly accepted name for a particular variation.