The phrase "gravity field" refers to the region around a massive object, such as Earth or another planet, where its gravitational force is experienced by other objects. This region extends infinitely far out into space, and its strength decreases as the distance from the center of the object increases. The gravity field affects objects in motion, such as the movement of celestial bodies or the trajectory of a spacecraft, and plays an important role in the behavior of fluids, such as water or air.