Fossil fuels are hydrocarbon-containing materials such as coal, oil, and natural gas that are formed naturally in the Earths crust from the remains of dead plants and animals. They are extracted and burned as fuel to provide heat for use directly (such as for cooking or heating), to power engines (such as internal combustion engines in motor vehicles), or to generate electricity. Some fossil fuels are refined into derivatives such as kerosene, gasoline, and propane before burning. The origin of fossil fuels is the anaerobic decomposition of buried dead organisms, containing organic molecules created by photosynthesis. Coal, crude oil, and natural gas are all considered fossil fuels because they were formed from the fossilized, buried remains of plants and animals that lived millions of years ago. Because of their origins, fossil fuels have a high carbon content.
Fossil fuels have played a dominant role in global energy systems and have been a fundamental driver of technological, social, economic, and development progress. However, using fossil fuels for energy has exacted an enormous toll on humanity and the environment, from air and water pollution to global warming. They are non-renewable resources that formed when prehistoric plants and animals died and were gradually buried by layers of rock. Over millions of years, different types of fossil fuels formed, depending on what combination of organic matter was present, how long it was buried, and what temperature and pressure conditions existed as time passed. Today, fossil fuel industries drill or mine for these energy sources, burn them to produce electricity, or refine them for use as fuel for heating or transportation.
