Primer

From GunCounter

A Primer contains a chemical compound that is more sensitive than powder and is used to ignite the powder. While there are electrically primed firearms, the majority of ones used and discussed here are impact sensitive and are set off by the impact of the weapon's firing pin.

The two major types of primers are:

Rimfire: the primer is spun into the rim of the cartridge during manufacturing. Example: .22 Long Rifle

Centerfire: As the name suggests, the primer is mounted in the center of the back of the cartridge.: Example: .38 Special . The 2 basic types of Centerfire primers are Boxer and Berdan.