A cartridge is a container that holds a specific item, often used in devices like printers or firearms. In printers, cartridges typically contain ink or toner, allowing the machine to produce text and images on paper. They are designed for easy replacement, making it convenient for users to maintain their printers. In firearms, a cartridge consists of a bullet, gunpowder, and a casing. When the trigger is pulled, the firing pin strikes the primer, igniting the gunpowder and propelling the bullet out of the barrel. This type of cartridge is essential for the operation of various firearms, including rifles and handguns.