E.ON is a European holding company based in Düsseldorf, North Rhine-Westphalia, Germany. It runs one of the world's largest investor-owned electric utility service providers, with around 26 million customers. Its diversified business consists of power generation, natural gas, energy trading, retail and distribution operations. It generates electricity from various sources, such as nuclear and hard coal, and other fuels, which include hydro, lignite, natural gas, and oil.