What is the most common type of fossil fuel?

The most common type of fossil fuel is coal, which is a combustible sedimentary rock that is formed from the remains of dead plants that have been subjected to heat and pressure over millions of years. Coal is primarily composed of carbon, hydrogen, oxygen, and nitrogen, and it is used primarily for electricity generation and steel production. According to the International Energy Agency (IEA), coal accounted for 27% of the world's primary energy consumption in 2020.

Oil and natural gas are also fossil fuels that are commonly used for transportation and heating, but they are less abundant than coal. Oil is a liquid that is formed from the remains of tiny plants and animals that lived in the ocean millions of years ago, while natural gas is a mixture of hydrocarbons that is found deep beneath the earth's surface.