Isaac Newton formulated the three laws of motion and the law of universal gravitation in Principia Mathematica.
Newton published his major work, Philosophiæ Naturalis Principia Mathematica, in 1687. In it, he presented a mathematical framework connecting the motion of objects on Earth with the motion of celestial bodies. His laws of motion describe how forces affect movement, while universal gravitation explains attraction between masses.
Newton’s ideas built on earlier work by scientists including Galileo Galilei and Johannes Kepler. Kepler had identified mathematical patterns in planetary orbits, and Newton showed how those patterns could follow from a general gravitational law. The achievement helped establish classical mechanics as a foundation of physics.
Newton is often credited with “discovering gravity,” but people had observed falling objects long before him. His distinctive contribution was expressing gravity as a universal, quantitative law and linking it to planetary motion.