A theory which states that space and time are actually a four-dimensional continuum known as "spacetime", and that
gravity is a manifestation of the curvature of the geometry of this four-dimensional spacetime. General Relativity explains the gravitational bending of starlight, how
gravity slows down the flow of time, predicts the existence of blackholes, and even predicts the expansion of the universe. The theory was formulated by Albert Einstein in order to incorporate
gravity into his theory of relativity.
The
famous eclipse experiment of 1919 confirmed Einstein's prediction that
light rays would bend in a gravitational field, according to his theory of general relativity.