Hydropower is electricity derived from converting the potential energy of water at different elevations and the kinetic energy of moving water. Hydropower traditionally refers to electricity generated at a dam as water stored behind the dam falls to a lower elevation. But the term can also refer to other technologies that generate electricity from water, such as tide power and wave power.
The first use of moving water to produce electricity was a waterwheel on the Fox River in Wisconsin in 1882, two years after Thomas Edison invented the incandescent light bulb. Shortly thereafter, the first of many U.S. hydroelectric power plants was completed in Niagara Falls, New York.