The principle behind Newton’s law of universal gravitation states that every mass attracts every other mass in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This fundamental law describes the attractive force of gravity acting on objects, which explains various phenomena such as the orbits of planets and the behavior of objects falling towards the Earth. It highlights the predictable nature of gravitational interactions and has formed the basis for further advances in physics.