Sturmgeschütz is a German word for "assault gun", usually abbreviated StuG. The vehicle was a leading weapon of the Sturmartillerie, a branch of the German artillery tasked with close fire support of infantry in infantry, panzer, and panzergrenadier units. StuGs were very successful in their intended support role and destroyed, among others, many bunkers, pillboxes and other defences. Destruction of enemy tanks eventually became its main priority as the German Army in the Soviet Union did not have sufficient gun power in many of its 1941-42 era tanks to take on the increased numbers of Soviet T-34 and KV-1 tanks. It is estimated that by 1944 StuG battalions had destroyed 20,000 enemy tanks, mostly T-34's.

The StuG is not generally considered to be a true tank because it lacks a turret. The gun was mounted directly in the hull, in a casemate-style fashion, with as low a profile as was possible to reduce vehicle height, and had a limited lateral traverse of a few degrees in either direction. Thus, the entire vehicle had to be turned in order to acquire targets. Omitting the turret made production much simpler and less costly, enabling greater numbers to be built. The lower vehicle height was meant to give a "StuG" designated vehicle a significantly shorter vertical profile as compared to contemporary tanks, making the StuG more difficult to hit and easier to protect in hull defilade.

In 1942 and 1943, the StuG was one of the most effective tracked vehicles of World War II in terms of opposition vehicles destroyed, and over 10,000 of them were eventually produced. The Germans were so excited by the initial Stug success that they turned to folly by producing the near useless Elefant "Stug" on obsolescent Porsche tank hulls. These Elefant's proved completely unwieldy and did not even have the regular Stug III and IV advantage of a low profile. By late 1943 improved Allied tanks and tank destroyers (US) with improved guns, rotating turrets, and superior mobility forced the Stug III and IV's into the corner of being primarily an ambush weapon.