Why does a rifle give backward kick on firing a bullet?

A rifle experiences backward kick, or recoil, when a bullet is fired due to the conservation of momentum. When the bullet is propelled forward out of the barrel, the rifle must move in the opposite direction to conserve the total momentum of the system. This reaction occurs because the force exerted on the bullet is equal and opposite to the force exerted on the rifle, resulting in the backward motion that the shooter feels.