Fossil fuels are made out of what was left over from ancient rivers, streams and swamps. It takes literally millions of years for layers of soppy organic matter to turn into fuels such as oil or coal. There is only so much fossil that has been made by the natural processes of our earth. We are using it all up.
The big problem is that we have grown so accustomed to using them in our daily lives that we dont' know how we will function without them. Gasoline, coal, oil and natural gas fuels our homes, factories and businesses. We have to start figuring out what we will use once all of it is used up. That's why people are trying to make fuels out of corn, decomposing organic waste and soybeans.
The scurry for fossil fuels is causing wars, costing money and leaving every nation in the country wondering exactly what it will do.