A Bren, an example of a Machine Gun.
Machine Guns are fully automatic firearms, used for suppression fire and against lightly armored or soft targets. Machine guns typically fire the same rounds used by rifles or heavier. Machine guns have seen use in almost every major conflict since World War One.
Machine guns saw heavy use in World War Two, and so are depicted in the Day of Defeat series. As in real life, they are excellent for suppression fire and against infantry.
Machine Guns in Day of Defeat and Day of Defeat: Source[]