A magazine follower is a small part used in modern firearms. As the name implies, it is used in firearms which are magazine-fed; these may, however, be bolt action or semiautomatic or even automatic weapons. In a firearm magazine, whether it is removable or built-in, the rounds being housed must be fed to the action of the weapon. Generally, magazines in modern weapons feed upwards, although this is by no means universally true. In any case, however, the rounds must be impelled towards the top or open part of the magazine where they can be fed into the chamber by the bolt or slide. To do this, a spring is generally used - either a spring that is dedicated to the magazine (in the case of removable magazines), or a spring attached to the weapon's action in the case of built-in versions. The force of the spring must be applied to the last round in the magazine in a manner which allows it to feed properly - which means a surfaced part which rests against the cartridge, between it and the spring. This part is called the magazine follower - it is part of the magazine, and it follows the rounds through the magazine. The shape of the follower will depend heavily on the type of round and the type of gun; some are mere flat plates, while others are complex plastic or resin or metal components which can handle staggered loading positions and are shaped to ensure they remain in the proper orientation even if the magazine is empty.