Millions of years ago, the earth was covered with swamps filled with multiple microorganisms, trees, and various leafy plants. As these organisms and plants eventually died, they drowned to the bottom of these swamps and oceans, forming layers of a material called peat.
Over millions of years, the peat was covered by sand, clay, and other minerals which converted the peat into sedimentary rock.
There are three types of fossil fuels. These include coal, mineral oil, and natural gas. They supply about eighty percent of the world energy, and can be obtained through mining and extraction within the land or oceans.