What are fossil fuels?

Fossil Fuels are a non-renewable source of energy that is formed from the remains of organisms that lived thousands of years ago.
Under several thousand feet of silt, flammable geologic deposits of organic materials, such as dead plants and animals, are known as fossil fuels. Due to the intense heat and pressure within the earth's crust, these deposits began to decay over time and were eventually transformed into natural gas, coal, and petroleum.