The Bofors 40 mm gun is an anti-aircraft

Anti-aircraft warfare

NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...

 autocannon

Autocannon

An autocannon or automatic cannon is a rapid-fire projectile weapon firing a shell as opposed to the bullet fired by a machine gun. Autocannons often have a larger caliber than a machine gun . Usually, autocannons are smaller than a field gun or other artillery, and are mechanically loaded for a...

 designed by the Swedish

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 defence firm

Defense contractor

A defense contractor is a business organization or individual that provides products or services to a military department of a government. Products typically include military aircraft, ships, vehicles, weaponry, and electronic systems...

 of Bofors Defence

Bofors

The name Bofors has been associated with the iron industry for more than 350 years.Located in Karlskoga, Sweden, the company originates from the hammer mill "Boofors" founded 1646. The modern corporate structure was created in 1873 with the foundation of Aktiebolaget Bofors-Gullspång...

 (the company was acquired in September 2000 by United Defense Industries

United Defense

United Defense Industries was a United States defense contractor which is now part of BAE Systems Land and Armaments. This company produces combat vehicles, artillery, naval guns, missile launchers and precision munitions.-History:...

 but is now a part of BAE Systems AB since March 2005). It was one of the most popular medium-weight anti-aircraft systems during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, used by most of the western Allies

Allies of World War II

The Allies of World War II were the countries that opposed the Axis powers during the Second World War . Former Axis states contributing to the Allied victory are not considered Allied states...

 as well as by the Axis powers

Axis Powers

The Axis powers , also known as the Axis alliance, Axis nations, Axis countries, or just the Axis, was an alignment of great powers during the mid-20th century that fought World War II against the Allies. It began in 1936 with treaties of friendship between Germany and Italy and between Germany and...

. The cannon remains in service as of 2011, making it one of the longest-serving artillery pieces of all time.