E = Energy

m = Mass

c² = Celeritas squared, the speed of light squared.

In E=mc², Mass and Energy are in a way interchangeable, however, one needs to be multiplied or divided by c² to be converted to the other.

Theoretically, just a little bit of mass can be converted into a large amount of energy, since mass IS concentrated energy. This is revolutionary because it opens up people's minds to unlocking an enormous amount of energy.