Crude oil, natural gas and coal are fossil fuels, Fossil fuels were formed from the fossilized remains of dead plants and animals that once lived millions of years ago, and are precious because they are non-renewable resources.

Oil and natural gas are the produces of the deep burial and decomposition of dead plants and animals. Heat and preassure, in the absence of oxygen, transform the decomposed material into tiny pockets of gas and crude oil. The oil and gas then migrates through the pores in the rocks to eventually collect in reservoirs.

Coal comes mainly from dead plants which have been buried and compacted beneath sediments. Most coal originated as peat in ancient swamps created many millions of years ago.