The word petroleum comes from the Latin petra, meaning “rock,” and oleum, meaning “oil.”
Petroleum is a liquid mixture of hydrocarbons which is present in suitable rock strata and can be extracted and refined to produce fuels including petrol, paraffin, and diesel oil; oil. A thick, flammable, yellow-to-black mixture of gaseous, liquid, and solid hydrocarbons that occurs naturally beneath the earth's surface, can be separated into fractions including natural gas, gasoline, naphtha, kerosene, fuel and lubricating oils, paraffin wax, and asphalt and is used as raw material for a wide variety of derivative products.
The oil industry classifies "crude" by the location of its origin and by its relative weight or viscosity ("light", "intermediate" or "heavy"). The relative content of sulfur in natural oil deposits also results in referring to oil as "sweet," which means it contains relatively little sulfur, or as "sour," which means it contains substantial amounts of sulfur.
Journal of Petroleum and Environmental Biotechnology covers various aspects of Petroleum & Environmental Biotechnology which quickly brings all the readers up to date with the state of the science in fast-moving areas of research.