Gravity is important because it is the force the holds everything in the universe together. Although it is the weakest of the four known natural forces, it is the most dominant of those forces. No matter the size of an object, it has a gravitational force that extends through all space.
Since the beginning of the universe, gravity has been present. Shortly after the Big Bang, gravity pulled atoms together to form the first stars and planets. It pulled the stars together to form galaxies and kept planets in orbit around their stars.
On Earth, gravity keeps people, buildings, air and water from floating into space. It causes the ocean tides and objects to fall to the ground.
Despite all the knowledge about what gravity does, no one fully understands how it works or why it exists. It is believed that gravity is the result of mass bending space instead of acting as a force, such as magnetism. Others believe objects exchange particles called gravitons that help create the gravitational attraction between the objects.
Both theories have plausible elements explaining how gravity works. Gravitons may bend space, or bending space may create gravitons. In his theory of relativity, Albert Einstein explained that gravity is more than a force, as the mass of an object causes the space around it to bend and curve.