What is Gravity?

Gravity is the tendency of bodies to move toward each other. In Newtons law of gravitational force he defined the magnitude of the gravitional force between two forces as "F = G M₁ M₂ / R²", and the direction towards the other object. Where G = is 6.67*10^-11 N*m²/kg².

http://www.earth.northwestern.edu/people/seth/202/lectures/intro/Image6.gif

We also know that F = ma so we can solve Newtons law of gravitation for the objects acceleration: a=G*M₂ / R². Substituting the mass of the Earth for M₂ and sea-level for R we get a=G (5.9742*10²⁴)/(6378.1*10³)² = 9.796 m/s².