It is a non-renewable source which means that this type of energy (crude oil) will not last forever and one day in the future it will run out.
All fossil fuels are called nonrenewable but not all non-renewable energy sources are fossil fuels.
Crude oil, coal and natural gas are all considered fossil fuels because they were formed from hidden remains of animals and plants that lived millions of years ago.
Crude oil is a naturally occurring, raw petroleum product composed of hydrocarbon deposits and further organic materials.
A form of fossil fuel, crude oil can be refined to yield usable products such as diesel, gasoline and various types of petrochemicals.