A bullet is a solid projectile fired by firearms such as pistols, machine guns or chainguns. They are usually of metal construction, primarily lead. In contrast to a shell, a bullet does not contain explosives.
The term bullet refers specifically to the metal slug that is propelled from a firearm via the mechanisms present in the cartridge within which it is contained. Although the term "bullet" is often improperly used to refer to the combination of bullet, case, gunpowder, and primer, such an item is properly called a cartridge. A cartridge without a bullet is called a blank.