Momentum is the product of an object's mass and velocity. It is a measure of how difficult it is to stop or change the direction of motion of an object. The greater the mass or velocity of an object, the greater its momentum. In other words, momentum is a property of moving objects that describes their tendency to keep moving in a straight line at a constant velocity. Momentum is conserved in a closed system (where no external forces act on the system), which means that the total momentum before an event equals the total momentum after the event. This principle is known as the law of conservation of momentum.
