The location inside a firearm, at the rear of the barrel, where a cartridge is positioned for firing.

In addition to aligning the cartridge with the barrel, the purpose of the chamber is to contain the pressure (tens of thousands of PSI) of a discharging cartridge. The case of the cartridge also plays a role in containing the pressure, but by itself the case cannot contain all of the pressure and would rupture if not enclosed in the chamber.

The cylinder of a revolver contains multiple chambers, one for each round that can be loaded in the firearm.