Fossil Fuels are predominately hydrocarbon material formed from plant material over geological time under heat and pressure. Examples include coal and oil and their derived products of petroleum or gasoline. A lot of coal comes from West Virginia, Wyoming and Pennsylvania. A lot of oil comes from the Middle East and Venezuela. The United States has many oil reserves that remain untapped due to interference from environmentalists. Because of the long time period required for fossil fuels to be produced in nature, fossil fuels are a finite resource. (See Hubbert's peak.)
Fossil fuels are used in the production of plastic, and burned as fuel or for heat.
Fossil fuels have been criticized as producing a lot of pollution, including sulfur dioxide (from small amounts of organic sulfur compounds), which sometimes produces acid rain, and carbon dioxide, a greenhouse gas.