Shotgun ammunition, commonly known as shotgun shells, is a type of cartridge designed specifically for use in shotguns. These shells typically consist of a plastic or paper casing filled with small pellets, known as shot, or a single projectile called a slug. The size and type of shot can vary, making shotgun ammunition versatile for different purposes, such as hunting, sport shooting, and self-defense. Shotgun shells are categorized by gauge, which indicates the diameter of the barrel. Common gauges include 12 gauge, 20 gauge, and 410 bore. Each gauge has its own specific applications and performance characteristics, allowing shooters to select the appropriate ammunition for their needs.