A simple but profound change to the understanding of gravity is that gravitational potential arises from changes in the energy stored in objects as mass. This replaces gravity as a distortion of the surrounding fabric of spacetime while mass remains constant. The stored energy is released as kinetic energy when objects move closer to each other. Mass reduces when the magnitude of the background and the speed of light increase. Massless photons do not lose energy in escaping a gravitational field. Instead, the energy stored in atoms increases. The apparent redshift of photons is a blueshift of atoms and massive clocks run faster. The revised understanding avoids the singularities at the centre of black holes. Changes in gravity, which propagate at the speed of light, can now cross the supposed event horizon, allowing black holes to rotate around each other. The increased speed of light, going back in time, means that the standard supernovae candles are more distant than assumed from their wavelength shift. This entirely removes the need for an accelerating expansion and yields the current rate at which time is slowing. The amount is in excellent agreement with the observed Pioneer anomaly. Moreover, it is demonstrated that the apparent, but now unneeded, dark energy is a necessary consequence of the assumption that mass is independent of the surrounding density of matter. It is also shown that the current explanation of the Pioneer frequency drift is untenable. The revised theory, labelled Full Relativity, overcomes the need for other ad hoc hypotheses, including dark matter and cosmic inflation, while yielding the standard predictions of General Relativity. It links inertia to the asymmetry of contributions to the background field from the chiral components due to matter and antimatter. The asymmetry determines the rotation frequency of the trapped angular momentum seen in the Compton wavelength of quantum mechanics. The dependence of inertia on asymmetry then explains the observed galaxy rotation curves and gravitational lensing without the need for dark matter. Various tests which will distinguish between the two forms of Relativity are put forward. Finally, gravity can now be linked with the other three forces in a way that is consistent with the Standard Model of particle physics.