Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons and is found in geological formations. It is a complex mixture of hydrocarbons, formed over millions of years from the remains of plants and animals. In other words, it’s literally a fossil fuel, existing in underground reservoirs and pools, in the gaps between sedimentary rocks, and near the surface in tar sands. The name petroleum covers both naturally occurring unprocessed crude oil and petroleum products that consist of refined crude oil. Crude oil makes much of the modern world possible.
Petroleum products are fuels that are made using crude oil and other hydrocarbons that are contained in natural gas.