An airburst round is a type of tacticalanti-personnel and anti-aircraft explosive ammunition, typically a shell or grenade, that detonates in midair, causing air burst effect fragment damage to enemy personnel or aircraft (notably comparably unsophisticated unmanned aircraft systems such as modified racing drones). In the latter case, airburst rounds are used in anti-aircraft or "zenith" cannon, known in military slang as FLAK (from the German "fliegerabwehrkanone", air defence cannon) or ack-ack (from the British phonetic alphabet, as an initialism for Anti Air).
This makes it easier to hit enemy soldiers behind a wall, in a defensive fighting position, or in a confined space or room. It is used on many guns, from artillery to the hand-held XM25 Individual Airburst Weapon System (derived from the XM29 OICW). Unlike traditional grenades, such as the 40 mm grenade, smart grenades can be electronically programmed to explode after traveling a certain distance. A fire control computer or some other electronic sighting system is used to quickly program the electronic fuse with any distance, as conditions dictate.
