Semi-automatic pistol in the context of "Recoil"

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.

A handgun is a firearm designed to be usable with only one hand. It is distinguished from a long barreled gun (i.e., carbine, rifle, shotgun, submachine gun, or machine gun) which typically is intended to be held by both hands and braced against the shoulder. Handguns have shorter effective ranges compared to long guns, and are much harder to shoot accurately. While most early handguns are single-shot pistols, the two most common types of handguns used in modern times are revolvers and semi-automatic pistols.

Before commercial mass production, handguns were often considered a badge of office — comparable to a ceremonial sword – as they had limited utility and were more expensive than the long barreled guns of the era. In 1836, Samuel Colt patented the Colt Paterson, the first practical mass-produced revolver, which was capable of firing five shots in rapid succession and quickly became a popular personal weapon, giving rise to the saying, "God created men, but Colt made them equal."

The Colt M1911 (also known as 1911, Colt 1911, Colt .45, or Colt Government in the case of Colt-produced models) is a single-action, recoil-operated, semi-automatic pistol chambered primarily for the .45 ACP cartridge.

A derringer or deringer is a small handgun that is neither a revolver, semi-automatic pistol, nor machine pistol. It is not to be confused with mini-revolvers or pocket pistols, although some later derringers were manufactured with the pepperbox configuration. The modern derringer is often multi barreled, and is generally the smallest usable handgun of any given caliber and barrel length due to the lack of a moving action, which takes up more space behind the barrel. It is frequently associated with discreet use by women because it is easily concealable in a purse or a stocking.

The original Philadelphia Deringer was a muzzleloading caplock single-shot pistol introduced in 1825 by Henry Deringer. In total, approximately 15,000 Deringer pistols were manufactured. All were single-barrel pistols with back-action percussion locks, typically .41 caliber with rifled bores and walnut stocks. Barrel length varied from 1.5 to 6 in (38 to 152 mm), and the hardware was commonly a copper-nickel alloy known as "German silver".

The SIG Pro is a series of semi-automatic pistols manufactured by SIG Sauer in Exeter, New Hampshire. It became the first polymer-frame handgun from SIG Sauer and one of the first pistols to feature a built-in universal accessory rail and interchangeable grips. Offerings in the series are chambered in .40 S&W, .357 SIG, or 9×19mm Parabellum. As of March 2020, only the SP 2022 variant was still listed on the SIG Sauer website. The SIG Pro was marketed as a lightweight and compact alternative to the "legacy" SIG Sauer handguns in an increasingly competitive and budget-oriented law enforcement market.

The 1931 Fabrique Nationale (FN) Baby Browning is a small blowback-operated semi-automatic pistol designed by Belgium-born Dieudonné Saive and based on John Browning's 1908 Vest Pocket pistol. Chambered in .25 ACP (6.35×15 mm), the pistol accepts a six-round magazine and features a manual safety. It uses a striker-fired, single action, blowback mechanism.

The .45 ACP (Automatic Colt Pistol), also known as .45 Auto, .45 Automatic, or 11.43×23mm is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol. After successful military trials, it was adopted as the standard chambering for Colt's M1911 pistol. The round was developed due to a lack of stopping power experienced in the Moro Rebellion in places like Sulu. The issued ammunition, .38 Long Colt, had proved inadequate, motivating the search for a better cartridge. This experience and the Thompson–LaGarde Tests of 1904 led the Army and the Cavalry to decide that a minimum of .45 caliber was required in a new handgun cartridge.

The standard-issue military .45 ACP cartridge uses a 230 gr (15 g; 0.53 oz) round-nose bullet at approximately 830 ft/s (250 m/s) fired from a government-issue M1911A1 pistol. It operates at a relatively low maximum chamber pressure rating of 21,000 psi (140 MPa), compared to 35,000 psi (240 MPa) for both 9mm Parabellum and .40 S&W, which due to a low bolt thrust helps extend the service lives of weapons. Since standard-pressure .45 ACP rounds are subsonic when fired from handguns and submachine guns, it is a useful caliber for suppressed weapons as it lacks the sonic boom inherent to supersonic rounds.