Gravity is a force that attracts matter to other forms or matter; it is a very weak force. It is the weakest of the fundamental forces, according to scientists. It is even weaker than what is called the weak force.
No one knows why gravity is so weak, but many scientists believe that if it was stronger or weaker than it is, the universe would be very different.
Isaac Newton described gravity as a force that is related to mass and distance. The gravitational pull of massive bodies such as the sun is much greater than the gravitational pull of small bodies, such as humans. But the farther away two objects are from each other, the weaker the gravitational pull. The sun has a considerable gravitational pull on Earth, for example. It is only 93 million miles away. But the sun's gravitational pull on the star Sirius is much less, because Sirius is light-years away. This demonstrates Newton's law of gravitation, which is (G * m1 * m2) / (d2).
Albert Einstein believed that gravity is a distortion in space-time, and not really a force. The great gravity of the sun creates a sort of sinkhole in which the planets spin around and around. Other physicists see gravity as a wave or a particle.