Einstein's Equation

Albert Einstein is indelibly associated with a famous equation: E=mc^2, relating the mass of an object to its energy. But that is not what physicists have in mind when they say "Einstein's Equation." The real Einstein's Equation is part of general relativity, which relates the curvature of spacetime to the mass and energy distributed within it. I will explain why the geometry of spacetime has anything to do with gravity, and how this famous equation expresses how spacetime curves.