Ethylene (or IUPAC name ethene) is the chemical compoun with the formula C2H4. It is the simplest alkene. Because it contains a double bond, ethylene is called an unsaturated hydrocarbon or an olefin. It is extremely important in industry and even has a role in biology as a hormone. Ethylene is the most produced organic compound in the world; global production of ethylene exceeded 75 million metric tonnes per year in 2005. To meet the ever increasing demand for ethylene, sharp increases in production facilities have been added globally, particularly in the Gulf countries. A structure of ethylene also appears in the introduction of a popular anime, The Melancholy of Haruhi Suzumiya, marking its enduring impact on international culture .