All modern handguns have three basic groups of parts.
- Action: The action, also known as the trigger group, contains the parts that fire the cartridges. Several types of actions are used in modern handguns.
- Frame: The frame is a metal housing that also serves as the handle (grip) of the handgun. All other parts are contained within it or connected to it.
- Barrel: The barrel is the metal tube that the bullet travels through. The handgun barrel is much shorter than a rifle or shotgun barrel because the gun is designed to be shot while being held with one or two hands, rather than being placed against the shooter's shoulder.
Repeating handguns (revolvers and semi-automatic pistols) hold more than one round of ammunition. A revolver uses a cylinder to store the ammunition, and a semi-automatic pistol uses a removable magazine that fits in the grip.