The Bren is a light machine gun (LMG) that was used by the British military during World War II. The gun was based on a Czechoslovak gun, the ZB z/26. The name is a shortening of "Brno-Enfield". Brno was the city where the earlier z/26 was made, and Enfield was the company that made the Bren.
It was a simple but well-made LMG. It was well-known for using a curved, top-loading magazine, a carrying handle, and being light enough for one man to carry and use. It was so popular that even the Japanese made their own LMG based on the Bren, the Type-99 light machine gun.
It was so popular among British soldiers that it was used by the British Armed Forces from 1938 to the 1990s.