9mm (9x19)

The **9x19mm Parabellum** — "9mm" to everyone who has ever bought a box — is the dominant defensive and competition pistol cartridge on earth. It's carried by most Western militaries, most U.S. police departments, and the vast majority of American concealed-carry holders. The appeal is boring in the best way: modest recoil, high magazine capacity, wide ammunition selection, and decades of defensive load development. Modern bonded hollow-points have closed most of the historical gap to heavier calibers in terminal performance while keeping the ergonomic advantages that made 9mm popular in the first place. It's also the most forgiving caliber to learn on. Every major handgun platform comes in 9mm first, which means the training ecosystem — classes, drills, courses of fire — is built around it.