A gun is a type of weapon designed to fire projectiles, typically bullets, at high speeds. It operates using a mechanism that ignites gunpowder or other propellants, creating a rapid expansion of gases that propel the projectile out of the barrel. Guns come in various forms, including handguns, rifles, and shotguns, each serving different purposes such as self-defense, hunting, or sport shooting. Guns are often categorized by their caliber, which refers to the diameter of the bullet, and their action type, such as semi-automatic or revolvers. The use and ownership of guns are regulated by laws that vary by country and region, reflecting differing views on safety and rights.