Gravitational forces are considered to be inherently linked to what we call 'mass'. There is a gravitational force of attraction between every object in the universe. The size of the gravitational force is proportional to the masses of the objects and weakens as the distance between them increases.
The force is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers of mass. This is called an inverse-square law.
