Gravitation is responsible for attracting two bodies with respective masses towards each other.
Therefore, every particle made up of matter exerts a gravitational force on every other particle in the universe.
Gravitation does not require any medium.
If and are the masses of the two bodies and is the distance between them, then according to the universal law of gravitation, the gravitational force exerted by these two masses towards each other is, where is the universal gravitational constant.