A magazine (also called a mag or, commonly but incorrectly, especially when removable, a clip) is an ammunition storage and feeding device within or attached to a firearm. Magazines may be integral to the firearm (fixed) or removable (detachable).
The cartridges in the magazine are loaded into the firearm either automatically or manually depending on the type of gun, but almost always by a spring. Some magazines can in turn be loaded by a clip; magazine and clip are not synonymous terms. The belt of linked ammunition used by most machine guns is an ammunition feeding device that is not a magazine, since it does not operate by feeding rounds out of a container.
The most common type of magazine is the detachable "box" type. Other types include the drum magazine, sometimes used with the Thompson submachine gun, the "pan" magazine of the Russian DP-28 machine gun, and the fixed "tube" magazine found on many lever-action and semi-automatic rifles and pump-action shotguns.