Oil refining refers to the processes involved in converting crude oil into useful petroleum products. Crude oil is often called "black gold" because of its thick, black consistency and high value. Crude oil is a form of petroleum, a complicated mixture of different hydrocarbons. A hydrocarbon is a chemical compound composed solely of hydrogen (H) and carbon (C). Hydrocarbon molecules in petroleum can contain from one to 50 carbon atoms. Crude oil itself is practically useless. The different fractions of the crude oil, however, are considered to be some of the most useful compounds on Earth. Oil refining turns crude oil into fuels and materials which can be used to make thousands of products. Almost half of the world's energy sources originate from crude oil. Petroleum products make up the majority of the items used by people every day, including bathing suits, toothpaste, soda bottles, clothing, and...