Question

what is gravitational force ?

Answer 1

the force which is applied by the gravity which is the force of earth is called gravitational force.

Answer 2

Newton explained that every particle of matter in the Brahmin attracts every other particle on its own. This omnipresent attraction force is called gravitational force.

Newton gave the following rules related to gravity-
 
The attraction between two fluid particles is inversely proportional to the square of the mass of the mass of the particle and the distance between them.
Its direction corresponds to the line joining both the particles

m1 ---------> F. F <------------- m2
| <-------------- r ------------------> |

The considered m1 or m2 mass of two particles is located at R distance from one another if the attraction force working between them is F, then by the rule of gravity


$f = \frac{gm1m2}{r {}^{2} }$