Mass as a Measure of the Amount of Inertia:
All objects resist alters in their state of motion because they have inertia. However some objects have more of a tendency to resist changes than others. The tendency of an object to resists alters in its state of motion differ with mass. Mass is that quantity that is solely dependent upon the inertia of an object. The more inertia that an object has, the greater it's mass. A more massive object has a greater tendency to resist alters in its state of motion.