A pistol is a type of handgun designed to be fired with one hand. It typically has a short barrel and is used for self-defense, sport shooting, and law enforcement. Pistols can be semi-automatic, where one bullet is fired with each pull of the trigger, or revolvers, which have a rotating cylinder that holds multiple rounds. Pistols come in various calibers, which refer to the diameter of the bullet. Common calibers include .22 LR, .9mm, and .45 ACP. The design and mechanism of pistols can vary widely, with many manufacturers producing models tailored for different purposes and preferences.