Oil and natural gas together make petroleum. Petroleum, which is Latin for “rock oil,” is a fossil fuel, meaning it was made naturally from decaying prehistoric plant and animal remains. It is a mixture of hundreds of different hydrocarbons molecules containing hydrogen and carbon that exist sometimes as a liquid (crude oil) and sometimes as a vapor (natural gas). Petroleum products include transportation fuels, fuel oils for heating and electricity generation, asphalt and road oil, and feedstock’s for making the chemicals, plastics, and synthetic materials that are in nearly everything we use today.