Newton's Faithful First Force Law
His First Law
Newton's First Law states that every object that is in motion, stays in motion, and every object at rest, stays in rest. This is always true unless acted upon by an enbalanced force. Things like skateboards stop, though, because they are acted upon a few forces, like friction. This guy is space, don't stop, though.
Inertia is a property of matter. It is the restistance for any object to change in a state of motion. It is the tendancy of objects to keep moving in a straight line at a constant velocity.