Dale has already contributed a good answer, but I'd like to supplement it. It's important not to confuse the terrain for the map. At a fundamental level, "gravity" is the word we use to describe certain real phenomena (that apples move towards the center of the Earth, that the Earth revolves about the Sun, and so on). Gravity is real, and we experience it every day. The *explanation* for gravity is a different thing. Newton explained gravity by a law of universal attraction. That turns out not to be completely accurate... that is, Newton's theory of gravity produces incorrect predictions for some things (like the orbit of Mercury). Einstein came up with a better theory of gravity that models it as a curvature of spacetime. So far this is the best theory of gravity that we have, but someday it will probably be superseded by a better theory. The explanation may change, but the facts (orbits of planets, etc.) won't, and any new theory will have to produce the same predictions as general relativity in the situations where GR has been tested.