A 9x19mm Parabellum is a nine millimeter wide bullet. It is usually used in handguns or submachine guns. The nine millimeter is often referred to as a "nine", "9mm", or "9x19". It is one of the most widely used bullets in history originating with the 9x19 Luger, invented in Germany. Many guns fire the 9mm, including the Walter p38, the Sten Mk II, the MP-40, the Uzi, the MP5, and the Glock 18. It is the standard handgun bullet for all NATO countries.