Natural gas is a fossil fuel composed of a mixture of hydrocarbon gases. The primary components are methane, ethane and propane. It is the cleanest-burning fossil fuel, producing byproducts of mostly carbon dioxide and water vapor. Natural gas provides approximately 25% of the United States' total energy consumption. The United States annually produces about 24% of the world's natural gas supply. Natural gas is used extensively in industrial and commercial applications, as well as homes.