A grenade launcher is a weapon that launches a grenade with more accuracy, higher velocity, and to greater distances than a soldier could throw it by hand.
Grenade launchers can either come in the form of standalone weapons (either single-shot or repeating) or attachments mounted under the barrel of a rifle. Alternatively, rifles have been designed to fire rifle grenades, either from their muzzle or from a spigot-type detachable launcher. Larger grenade launchers may be mounted on vehicles.
Question: Just how does the modern grenade launcher works?