A long, long time ago -- well, the middle of the 1800s to be exact -- electricity was an intriguing but mostly useless thing. Some factories and residences toyed with early electric lights and motors powered by on-site generators, but most of the world used piped steam and natural gas to heat their homes and drive their machines for decades after electrification began. That would all change, however, with Nikola Tesla's invention of three-phase high-voltage power distribution at the end of the 1800s and the creation of the world's first synchronized national electricity grid in Great Britain in 1938.