Submachine Guns

A submachine gun, abbreviated SMG, is a magazine-fed, automatic carbine designed to fire handgun cartridges. The term “submachine gun” was coined by John T. Thompson, the inventor of the Thompson submachine gun, to describe its design concept as an automatic firearm with notably less firepower than a machine gun (hence the prefix “sub-“). Submachine gun is lighter than a rifle and has more firepower. The downside is shorter effective distance compared to a rifle.

-Wikipedia