The word "pistol" is often synonymous with the word "handgun". Some handgun experts make a technical distinction that views pistols as a subset of handguns.
Sometimes in American usage, the term "pistol" refers to a handgun having one chamber integral with the barrel, making pistols distinct from the other main type of handgun, the revolver, which has a revolving cylinder containing multiple chambers.
But UK/Commonwealth usage often does not make this distinction. For example, the official designation of the Webley Mk VI was "Pistol, Revolver, Webley No. 1 Mk VI", and the designation "Pistol No. 2 Mk I" was used to refer to both the Enfield Revolver and the later Browning Hi-Power semi-automatic.
Handheld firearms were first made in China where gunpowder was first developed. They were hand cannons (although they were not necessarily fired from the hand, but rather at the end of a handle). By the 14th century, they existed in Europe as well. The first handheld firearms that might better be called "pistols" were made as early as the 15th century, but their creator is unknown.
By the 18th century, the term came to be used often to refer to handheld firearms. Practical revolver designs appeared in the 19th century, but it was not until the mid-twentieth century that the (sometimes-observed) differentiation in usage of the words "pistol" and "revolver" evolved among some speakers and the use of "handgun" became prevalent.
Single-shot pistols are the simplest possible form of pistols and are known to have existed in AD 1365. The earliest handguns were single-shot, muzzle-loading guns with ignition provided by inserting a smoldering match cord into a touch hole. As such, they were essentially nothing more than miniature cannons, small enough to be handheld.
Improvements followed in subsequent centuries, as various types of locks (ignition devices) were invented. In the matchlock, the separate match cord was affixed to a spring-loaded pivot which could be tripped by a trigger. In the wheellock, a mechanism analogous to that used in today's cigarette lighters replaced the smoldering match cord.
In the 17th century, the flintlock, which strikes a flint against steel, appeared. (The flintlock, amazingly, remained state-of-the-art for some two hundred years.) In the 19th century, percussion caps were developed, followed shortly by modern integrated-primer cartridges, and hammers therefore traded their flint for firing pins.
An example of a single-shot pistol is the flare gun. Although not intended to be a weapon, many variants have been made (See Flare gun). One example is the Kampfpistole, or Sturmpistole in its final form. The weapon was designed to function as an anti-tank weapon.
Single-shot pistols continue to be manufactured today and are often used for target shooting. They are also sometimes used for handgun hunting of game, including big game. The most powerful handguns are capable of killing all game, including elephants.(wikipedia.org)