The purpose of this site is to provide an overview and introduction to the concepts behind the theory of relativity. Likely, if you found your way here, you probably know little about relativity beyond it having something to do with E and mc.
There are actually two distinct theories of relativity. This site provides a little insight into some key concepts of each theory. The information is graphically presented for those unfamiliar with the theories.

Special relativity is the first of the two that Einstein put to paper. It is the physics behind the behavior of time and light.

General relativity is the science of the universe on a grand scale. It deals with large bodies on the order of planets and stars and delves into the nature of gravity. It is within the realm of general relativity that black holes are thought to exist.