Anti-aircraft artillery is artillery which is designed to shoot down aircraft. Other names are triple-A (from the initials AAA), air defence artillery, and flak (from German Flak, short for Fliegerabwehrkanone, meaning anti-aircraft gun).
There are two main forms of anti-aircraft artillery: single-shot weapons and autocannon.
Single-shot weapons were popular during World War II but are little used now. They fire one shell at a time at an aircraft. The shell is usually fitted with a prozimity fuze or time-delay fuze to send exploding "flak" into a specified area. A good example is the German 88 mm gun.
