Coal: What is is made of?? How is it formed??

Coal is a fossil fuel and most of our coal was formed when most of the earth was covered in swamps, 300 million years ago. As plants and animals started to die there remains sank to the bottom of the swampy areas and they started to layer on top of each other this soon made a material called peat and after awhile all the layers started to get packed together more and it made coal!! Coal is mostly made of carbon, along with some sulfur, hydrogen, oxygen and nitrogen.