The 8.8 cm Flak 18/36/37/41 is a German 88 mm anti-aircraft and anti-tank artillery gun, developed in the 1930s. It was widely used by Germany throughout World War II and is one of the most recognized German weapons of the conflict. The gun was universally known as the Acht-acht ("eight-eight") by the Germans and the "eighty-eight" by the Allies. Due to its lethality, especially as a tank killer, the eighty-eight was greatly feared by Allied soldiers.

Anti-aircraft warfare is the counter to aerial warfare and it includes "all measures designed to nullify or reduce the effectiveness of hostile air action". It includes surface based, subsurface, and air-based weapon systems, associated sensor systems, command and control arrangements, and passive measures. It may be used to protect naval, ground, and air forces in any location. However, for most countries, the main effort has tended to be homeland defence. Missile defence is an extension of air defence, as are initiatives to adapt air defence to the task of intercepting any projectile in flight.