What is Newton's First Law often referred to as?

Newton's First Law is often referred to as the law of inertia. This fundamental principle states that an object at rest will remain at rest, and an object in motion will continue moving at a constant velocity unless acted upon by a net external force. The term "inertia" refers to the tendency of objects to resist changes in their state of motion. This means that without any external influence—a force like friction, gravity, or applied force—objects will not start moving, stop moving, or change direction on their own.

The concept of inertia is vital in understanding motion in physical science, as it lays the foundation for further principles and laws of motion that Newton later developed. Recognizing this property of matter helps illustrate how forces interact with objects in various scenarios, forming the basis for classical mechanics. Other laws of motion defined by Newton, while important, describe different relationships between forces and motion rather than the inherent property of resistance to change that inertia encapsulates.