Why does gravitational potential energy have a negative value?

The negative value stems from the definition of gravitiational potential energy which states that it is equal to the work done by the gravitational field moving a body to its given position from infinity. At an infinite distance away from any other mass, a body would have gravitational potential energy equal to zero. As the body moves closer to the mass, it loses gravitiational potential energy x. Hence, it has negative energy as shown:Energy at current = Energy at start - Energy lost = 0 - x = -x(Where x is the energy lost)