Gravity is a natural phenomenon in the universe due to which every body having a mass attracts every other body having a mass. It is discovered by the Great scientist Isac Newton.
Gravity = gravitational Force of attraction = G M m / d² ,
where G = universal gravitational constant.
M and m are masses of two objects
d = distance between centers of mass of the objects
The force of attraction is called force of gravitation or gravity. On Earth the force of attraction exerted by the Earth on our body gives rise to our weight. It is the force with which we drop back to the Surface of Earth, when we jump a few feet high.
For an object on surface of Earth, gravitational Force = weight
= G Me m / Re² = m g, where g = G Me/Re²
Me = mass of Earth, and Re = radius of Earth
The acceleration with which we fall back on Earth's surface is called the acceleration due to gravity and is denoted by "g".