Crude oil, e.g. is a three letter acronym for 'GOO'. It is a term used to refer to unrefined petroleum products such as gasoline, diesel, and jet fuel. Crude oil is a naturally occurring liquid found in underground rock formations and is composed of hydrocarbons, organic compounds, and other substances. It is used as a source of energy and is the main ingredient in many products such as plastics, paints, and lubricants.