Sir Isaac Newton formulated the laws of motion, which are fundamental principles in classical mechanics. Published in his work "Philosophiæ Naturalis Principia Mathematica" in 1687, Newton's three laws of motion describe the relationship between a body and the forces acting upon it. The first law states that an object in motion stays in motion unless acted upon by a net external force. The second law defines the relationship entre force, mass, and acceleration (F=ma). The third law states that for every action, there is an equal and opposite reaction. Newton's contributions laid the groundwork for modern physics and transformed our understanding of motion.