Olefins are petrochemical derivatives produced by cracking feedstocks from raw materials such as natural gas and crude oil. Lower olefins have short chains with only two, three or four carbon atoms, and the simplest one is ethylene. The higher olefins have chains of up to twenty or more carbon atoms. The main olefin products are ethylene, propylene, butadiene and C4 derivatives. They are used to produce plastics, as chemical intermediates, and, in some cases, as industrial solvents.