A form of petroleum that's unrefined, in its natural form as it was when taken from the ground. It's the basis for motor oil, gasoline, heating oil, diesel oil, kerosene and other petroleum-based products. This product is extracted from an oil field such as the Middle East, the Gulf of Mexico or the North Sea Oil field. The product itself comes in a large variety of colors and consistencies. It can be as light as straw colored all the way to dense pitch black.
The carbon atom number determines the oil's "weight" or density. Gases such as natural gas generally have one to four carbon atoms, while heavy oils and waxes may have up to 50. Asphalt or Bitumen might have hundreds of carbon atoms.
One class of crude oil is Light sweet crude.
The petrochemical industry takes this raw material and makes many different products including plastics such as pvc pipe, house paint, explosives, pharmaceuticals etc.