The Sten Gun, or simply Sten, was a submachine gun developed for the British Army as an emergency weapon at the beginning of the Second World War. The Sten, officially classified as a machine carbine, was designed as a cheap and easy-to-manufacture weapon so that it could be produced on a large scale. It was intended to complement the Thompson Submachine Guns, considered to be of better quality, but also much more difficult to acquire in the necessary numbers.

The weapon did not have sight adjustment or fire selector. Its stock was made from a single piece of folded steel. In general, all models manufactured of this weapon had cases of frequent malfunctions caused by its single-exit bifilar magazine and the low-quality ammunition used by the British. As it was an extremely cheap weapon, it was widely distributed to a large number of armies and resistance forces that rose up against the Axis.

Despite its defects, the Sten Gun was one of the most formidable weapons used during the Second World War, having a great influence on the outcome of the conflict. After the war, it continued to be used by the British army until it was replaced by the Sterling Submachine Gun.

Today, it is known that at least 6 million Sten were produced during World War II.