The M1 Carbine (formally the United States Carbine, Caliber .30, M1) is a lightweight semi-automatic carbine that became a standard firearm in the U.S. military during World War II and the Korean War, and was produced in several variants. It was widely used by U.S. and foreign military and paramilitary forces, and has also been a popular civilian firearm. In selective fire versions capable of fully-automatic fire, the carbine is designated the M2 Carbine. The M3 Carbine was an M2 with an active infrared scope system.