The term "9mm" typically refers to a type of ammunition used in firearms. It denotes the diameter of the bullet, which is 9 millimeters. This caliber is popular for handguns and is known for its manageable recoil and effectiveness in self-defense situations. Common examples of firearms that use 9mm ammunition include the Glock 19 and Beretta 92. In addition to its use in firearms, "9mm" can also refer to the 9mm Parabellum, a specific cartridge developed in the early 20th century. It has become one of the most widely used handgun cartridges globally, favored by military, law enforcement, and civilian shooters alike for its balance of power and control.