Newton’s First Law of Motion also called the Law of Inertia. A stationary object wants to stay at rest forever and a moving object wants to move along a straight line with constant momentum if no external force is applied. In both cases, the object is prevented from changing its state of rest and state of motion. This property of matter is called Inertia.
Newton’s first law of motion speaks of this physical property of matter. Hence Newton’s First Law of Motion also called the Law of Inertia.