I. Sources and Uses of Oil

Crude oil, also known as petroleum, is a naturally occurring energy-dense liquid hydrocarbon. Oil is known as a fossil fuel because it is formed from fossilized plants and algae that existed millions of years ago. Most oil that is extracted in the United States is refined into petroleum products, including diesel fuel, gasoline, and oil used to heat homes and businesses. Oil can also be used to manufacture plastic products and fertilizers.

Oil can be classified as...