A rocket-propelled grenade (often abbreviated RPG) is a shoulder-fired anti-tank system that fires rockets equipped with an explosive warhead. Most RPGs can be carried by an individual soldier. These warheads are affixed to a rocket motor which propels the RPG towards the target and they are stabilized in flight with fins. Some types of RPG are reloadable with new rocket-propelled grenades, while others are single-use. RPGs, with some exceptions, are generally loaded from the muzzle.

Source: https://en.wikipedia.org/wiki/Rocket-propelled_grenade