Petrol is made from unprocessed crude oil, also known as petroleum. The name "petrol" often refers to the unprocessed crude oil and the processed products made up of this type of oil.
Along with oil and coal, petroleum is classified as a fossil fuel. Formed over millions of years, fossil fuels are non-renewable energy sources. When it is first collected, petroleum is a black, green or clear liquid with various levels of thickness. Petrol results from the mixing of crude oil with natural gas, and it may vary from a heavy black consistency to a pale yellow color (with low viscosity). The advantages of petrol as an energy source reside in the fact that it is clean burning and possesses a high energy density.
Both crude oil and natural gas are obtained from the ground, either on land or underwater. The extraction process involves sinking an oil well in the ground. A ship or pipeline then transports the oil to refineries where it is transformed into petrol. The refining process has several stages, including distillation, reforming, cracking and isomerization. Besides being the base substance for producing petrol, crude oil is also an ingredient for lubricating oils, fuels, asphalt, waxes and petrochemicals.