While others before him had made important observations about motion, it was Newton who, in his book *Philosophiæ Naturalis Principia Mathematica* (Mathematical Principles of Natural Philosophy), published in 1687, formulated the three laws of motion that are still fundamental to our understanding of how objects move.
These laws are:
1. Law of Inertia: An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
2. Law of Acceleration: The acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to its mass.
3. Law of Action-Reaction: For every action, there is an equal and opposite reaction.
While Newton's laws aren't perfect (Einstein's theory of relativity provides a more complete picture at very high speeds), they provide a remarkably accurate framework for understanding the motion of objects in our everyday world.
