small firearm designed for one-hand use. According to one theory, pistols owe their name to the city of Pistoia, Italy, where handguns were made as early as the 15th century. The pistol was originally a cavalry weapon. The military advantages of a firearm that could be operated by one hand, leaving the other free for another weapon or for defense, were clear from the earliest days of gunpowder, and the pistol evolved simultaneously with such shoulder weapons as the harquebus and musket.

There are two important classes of pistol: revolvers (revolver) and automatics. Revolvers embody an element that revolves; in early revolvers, sheaves or bundles of tubes serving as barrels were revolved by hand to allow more than one shot without reloading. The modern revolver employs a short, many-chambered cylinder positioned behind a single barrel so that the cartridge in each chamber is brought successively in alignment with the barrel. Pulling the trigger revolves the cylinder, brings a fresh cartridge in line with the hammer, locks the cylinder in place, and releases the hammer to discharge the cartridge.

Automatic pistols have their mechanism actuated by the energy of recoil when a bullet is fired; cartridges are fed into the mechanism through a magazine in the butt of the pistol. Though devotees of the automatic pistol have predicted the decline and disappearance of the revolver, there is little evidence that this is happening. Both weapons are used by the military in many countries, in which context they usually serve as sidearms for officers. Their use by police and security forces varies, with the revolver favoured in the United States and the automatic used elsewhere. Both types are used extensively for sport and target shooting. See also automatic pistol; revolver.