Momentum and its cousin angular momentum are other very powerful quantities. Ordinary momentum is a measure of an object's tendency to move at constant speed along a straight path. Momentum depends on speed and mass. A train moving at 20 mph has more momentum than a bicyclist moving at the same speed. A car colliding at 5 mph does not cause as much damage as that same car colliding at 60 mph.
Angular momentum measures an object's tendency to continue to spin.
A torque is simply a force acting along a line that is off the object's spin axis. In these cases, we have conservation of angular momentum. The area swept out by a line connecting an orbiting object and the central point is the same for any two equal periods of times. That line is called a radius vector in the following discussion. The rate of change of the swept-out area does NOT change with time.