Ammunition refers to the various types of bullets, shells, cartridges, or other projectiles used in firearms or other weapons. The following are the most common types of ammunition:

1. Bullets: These are the most basic type of ammunition and are used in firearms such as pistols and rifles. They consist of a metal projectile that is fired from the weapon.

2. Shotshells: These contain multiple small projectiles, or "shot," that spread out upon firing. Shotguns use these types of rounds for hunting and self-defense.

3. Cartridges: These are self-contained ammunition units that consist of a bullet, casing, powder, and primer. They are commonly used in pistols and rifles.

4. Grenades: These are explosive devices that can be thrown by hand or launched from a launcher. They are designed to explode upon impact and can be used for a variety of purposes, including military tactics and riot control.

5. Rockets: These are projectiles that are propelled by a rocket motor and are designed to fly for a significant distance before exploding. They are often used in military settings.

6. Missiles: These are self-propelled guided projectiles that can be fired from ground or air-based launchers. They are often used in military settings, particularly for air defense and ground-to-air attacks.

Overall, there are many different types of ammunition available, each designed for specific purposes and applications.