A "20-gauge" refers to a specific size of shotgun, which is a type of firearm. The term "gauge" indicates the diameter of the shotgun barrel, with a lower number representing a larger bore. A 20-gauge shotgun is smaller than a 12-gauge, making it lighter and easier to handle, especially for beginners or those with less upper body strength. In terms of ammunition, a 20-gauge shell typically contains less lead shot than a 12-gauge shell, resulting in less recoil. This makes the 20-gauge popular for various uses, including hunting small game and clay shooting. It is also commonly used in sport shooting and home defense.