Derringer in the context of "Break action"

A pistol is a type of handgun, characterized by a barrel with an integral chamber. The word "pistol" derives from the Middle French pistolet (c. 1550), meaning a small gun or knife, and first appeared in the English language c. 1570 when early handguns were produced in Europe. In colloquial usage, the word "pistol" is often used as a generic term to describe any type of handgun, inclusive of revolvers (which have a single barrel and a separate cylinder housing multiple chambers) and the pocket-sized derringers (which are often multi-barrelled).

The most common type of pistol used in the contemporary era is the semi-automatic pistol. The older single-shot and lever-action pistols are now rarely seen and used primarily for nostalgic hunting and historical reenactment. Fully-automatic machine pistols are uncommon in civilian usage because of their generally poor recoil-controllability (due to the lack of a buttstock) and strict laws and regulations governing their manufacture and sale (where they are regarded as submachine gun equivalents).

In American English, a pocket pistol is any small, pocket-sized semi-automatic pistol (or less commonly referencing either derringers, or revolvers), and is suitable for concealed carry in a pocket or a similar small space.

Pocket pistols are sometimes categorized as smaller than sub-compact pistols, but the distinction is not clear-cut as some small sub-compact pistols may be categorized as pocket pistols, and some large pocket pistols may be classified as sub-compact pistols.

In firearm designs, the term single-shot refers to guns that can hold only a single round of ammunition inside and thus must be reloaded manually after every shot. Compared to multi-shot repeating firearms ("repeaters"), single-shot designs have no moving parts other than the trigger, hammer/firing pin or frizzen, and therefore do not need a sizable receiver behind the barrel to accommodate a moving action, making them far less complex and more robust than revolvers or magazine/belt-fed firearms, but also with much slower rates of fire.

The history of firearms began with muzzleloading single-shot firearms such as the hand cannon and arquebus, then multi-barreled designs such as the derringer appeared, and eventually many centuries passed before breechloading repeating firearms became commonplace. Although largely disappeared from military usage due to insufficient firepower, single-shot firearms are still produced by many manufacturers in both muzzleloading and cartridge-firing varieties, from zip guns and ultra-concealable pocket pistols to the highest-quality hunting and match rifles.

Small arms and light weapons (SALW), in arms control protocols, are two main classes of man-portable weapons.

Small arms, broadly speaking, are individual-service (i.e. for carry and operation by individual infantrymen) kinetic projectile firearms. These include: handguns (revolvers, pistols, derringers, and machine pistols), muskets, rifled muskets, shotguns, rifles (assault rifles, battle rifles, carbines, designated marksman rifles, short-barreled rifles, sniper rifles, etc.), submachine guns, personal defense weapons, squad automatic weapons, and light machine guns.