what is fossil fuel? why is it called so?

Dear student, Fossil fuels are the preserved remains or traces of plants , animals or other organisms from the past. They are derived from the remains of living organisms that were buried by sediments. Fossil fuels can be solids, example coal and they can be liquid , example crued oil. Fossil fuels are called so because they were formed many hundreds of millions of years ago before the time of the dinosaurs. HOPE THIS HELPS. REGARDS!