Tiger I is the common name of a German heavy tank developed in 1942 and used in World War II. The final official German designation was Panzerkampfwagen VI Tiger Ausf. E, often shortened to Tiger. The Tiger I gave the Wehrmacht its first tank which mounted a KwK 36 88mm gun in an armoured fighting vehicle. The KwK 36 is not to be confused with the earlier and similar 8.8 cm Flak 36, a different weapon designed in parallel with the KwK 36 and firing the same ammunition ("KwK" denotes an armored vehicle gun, while "Flak" denotes anti-aircraft artillery). During the course of the war, the Tiger I saw combat on all German battlefronts. It was usually deployed in independent heavy tank battalions, which proved highly effective.

Source: Wikipedia, "Tiger I", available under the CC-BY-SA License.