All the energy we use comes from the earth. The electricity we use every day doesn’t come directly from the earth, but we make electricity using the earth’s resources, like coal or natural gas.
Both coal and natural gas are called “fossil fuels” because they were formed deep under the earth during dinosaur times.
The problem is that fossil fuels can’t be replaced – once we use them up, they’re gone forever. Another problem is that fossil fuels can cause pollution.