Recoil is the backward movement experienced by a firearm or other projectile-launching device when it is fired. This occurs due to Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. When a bullet is propelled forward, the gun pushes back in the opposite direction, resulting in recoil. The amount of recoil can vary based on several factors, including the type of firearm, the weight of the bullet, and the amount of gunpowder used. Heavier firearms, like shotguns, typically have less perceived recoil due to their weight, while lighter firearms, such as handguns, may produce a more noticeable kick.