coal, oil and natural gas
The first thing I can tell you is that coal is nonrenewable. Also coal is made from the pressure of heat and magma over millions year. People mine coal like any other treasure gold diamond and coal underground. Coal produces electricity energy sent to power plants for electric energy.
oil spills often happen and creates a huge disaster. Which kill lots of animals in the water and all most imposible to clean up. Oil will soon run out because sources are limited from the fossil fuel.
Natural gas is made of dead animals decomposed heated and pressured. Sent to power plants really hot and in to your homes to make stoves work and other things that produces heat. Like this picture in front of you its a flame, natural gas is really hot most of the time.