A centerfire cartridge is a cartridge with a primer located in the center of the cartridge case head. Unlike rimfire cartridges, the primer is a separate and replaceable component.

Centerfire cartridges have supplanted the rimfire variety in all but the smallest cartridge sizes. With the exception of a few .17 caliber and .22 caliber pistol and rifle cartridges, small-bore shotgun cartridges (intended for pest-control), and a handful of antique, mostly obsolete cartridges, almost all pistol, rifle, and shotgun ammunition used today is centerfire. (source)