Gravity is the natural, invisible force that pulls things in. Without gravity, all of the planets, stars, Earthlings, Earthlings' properties, and etc. can go flying all around the universe. Earthlings can die if there weren't any gravity pulling them in. Gravitational pull from the sun is what keeps the planets in their orbits. It is the force that acts upon everything.
|Sir Isaac Newton found the theory of Universal Law of Gravitation|
after an apple fell on his head.