A carbine ( KAR-been or KAR-byn) is a long gun that has a barrel shortened from its original length. Most modern carbines are rifles that are compact versions of a longer rifle or are rifles chambered for less powerful cartridges.

The smaller size and lighter weight of carbines make them easier to handle. They are typically issued to high-mobility troops such as special operations soldiers and paratroopers, as well as to mounted, artillery, logistics, or other non-infantry personnel whose roles do not require full-sized rifles, although there is a growing tendency for carbines to be issued to front-line soldiers to offset the increasing weight of other issued equipment. An example of this is the U.S. Army's M4 carbine, which is standard issue.