What was D-Day in World War 2?

D-Day is the famous term for the return to Western Europe by Allied armies, who made massive amphibious landings on the beaches of Normandy, France on June 6, 1944.

Allied forces made an amphibious assault on 5 beaches of German occupied northern France: Utah, Omaha, SWord, Juno, and Gold. The German occupation forces, plagued by misinformation and tactical errors, were pushed back through France and the Low Countries during the following 11 months. Combined with the demands of the Eastern Front, the new theater overtaxed the ability of the German armies.

While a common military term (such as H-Hour) to denote the start of an operation, the term rapidly became synonymous with the momentous Normandy landings.