Universal Law of Gravitation

"Every object of the universe attracts other object .the force of attraction between them is directly proportional to product of their masses and is inversely proportional to the square of distance between them.this force is along the line joining the centre of both the objects"

Mathematical form of Newtons Universal Law of Gravitation

F (gravitational force acting) = G*m1*m2/r^2

where G is the constant , m1 and m2 are masses of the two bodies and r is the distance between them. so from this we can assume that

G= F*r^2/m1*m2

Now as the mathematical form of law of gravitation remains same at any place in universe and we derive gravitational constant from that law, so it is also constant all over universe .

Henry Cavendish found the value of G which is 6.67*10^-11.

what is the technical difference between "Gravity" and "Gravitation"?

They are often used interchangably, but gravitation often refers to the theory or concept of gravity in general, and is more often than not used in its adjectival form gravitational. Gravity often refers the gravitational field itself (a vector quantity or its magnitude). For example, being on earth, you are subject to the force of gravity. Your weight is a gravitational effect. Also, gravity tends to be the term of choice in Newton's (field) theory of gravity. Gravitation tends to be the term of choice in general relativity, in which there is no gravity field, per se.