What is gravitational potential energy? Why is gravitational potential negative,and what does it mean?

(N/A) Gravitational potential energy is the energy possessed by an object due to its position in a gravitational field. It is defined as the work done by an external agent in bringing a body from infinity to a point in the gravitational field without acceleration.
The gravitational potential $V$ at a point is given by $V = -GM/r$,where $G$ is the gravitational constant,$M$ is the mass of the source,and $r$ is the distance from the source.
The negative sign indicates that the gravitational force is attractive in nature. It means that the gravitational potential energy of a system of two masses is zero at infinity and decreases as the masses are brought closer together. Thus,work must be done by the gravitational field to bring the masses together,or conversely,an external agent must do negative work to move the body from infinity to a point $r$.