Gravity is the force exerted by all objects having mass on all other objects having mass. As first suggested by Newton, the acceleration of a mass m towards a second mass M is given by

(1)

where G is the gravitational constant and r is the separation distance between the two masses. By equating with the gravitational force equation

(2)

it can be seen that gravity is just the force per unit mass exerted on one body by another,

(3)

In order to avoid the complications produced by the fact that not only does M exert a force of m, but m also exerts a forces on M, the m is usually taken to be a "test particle" so that (where means "is much less than".)

Magnitudes of various effects on Earth's gravity field are summarized in the following table.

mass	1
oblateness
mantle convection
local topography

The theory of general relativity describes the phenomenon of gravity very differently.

General Relativity, Gravitation, Gravitational Constant, Gravitational Field, Gravitational Force, Gravitational Mass, Gravitational Potential, Gravitational Potential Energy