Conservation of Momentum is a fundamental principle in physics stating that the total momentum of a closed system remains constant if no external forces act on it. Momentum, which is the product of an object's mass and its velocity, can be transferred between objects during interactions, such as collisions. For example, when two billiard balls collide, the momentum before the collision equals the momentum after the collision. This principle applies to various scenarios, from car crashes to rocket launches, helping scientists and engineers predict the outcomes of these events accurately.