Coal, oil and natural gas are all called fossil fuels because they are items that can be used as fuel in the modern world. They have been around for a long time. In fact, time is responsible for making them the type of organic material that they are now. They have been exposed to the earth’s natural heat and pressure from the crust.
Without these things, they wouldn’t be the fossil fuels that they are today. There are different types of fossil fuels that are available but they are starting to become fewer because of people’s consumption. The time may come when there will not be enough fossil fuels to sustain the world.