The MP 18 is a German submachine gun designed and manufactured by Bergmann Waffenfabrik. Introduced into service in 1918 by the German Army during World War I, the MP 18 was intended for use by the Sturmtruppen, assault groups specialized in trench combat, as a short-range offensive weapon that would provide individual soldiers with increased firepower over a pistol.

A submachine gun (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. As a machine gun must fire rifle cartridges to be classified as such, submachine guns are not considered machine guns.