It is the force experienced by a unit mass placed at that point.
Let M be the mass of a body around which a gravitational field exists. In order to get the gravitational field intensity at point P in the gravitational field, at test mass m is placed at the point P.
If a test mass m, at a point P in the gravitational field, experience a force F, then
Where r is the distance of P from the centre of the body producing the gravitational field. If r= ∞ ,then I= 0 It means the intensity of gravitational field is zero only at infinite distance from the body.