Hydroelectricity is confirmed as the prime renewable technology in terms of installed capacity. Hydroelectric energy has undergone a very rapid development which is still continuing in industrialised countries and developing countries of Asia and Latin America, potentially rich in resources. Also in terms of exploitation of available hydroelectric resources, Western Europe and the United States are the world leaders and use almost all the available resources. China, Brazil, the United States, Canada, Russia and India were confirmed as the top countries for installed capacity. The use of hydroelectric energy is much more limited in Eastern and developing countries, where the energy produced by hydroelectric power plants could be increased remarkably. The installed capacity of Africa is remarkably low as compared to the huge potential of the continent.