A fuel is something you burn to make energy. Energy is what makes things go -- for example, cars, stoves, vacuum cleaners and water heaters. All motors have to have some kind of energy, such as electricity, gas or other fuels, to run. Fossil fuels are called a “non-renewable” source of energy, which means that once the world runs out, it can’t make more.

Fossil fuels are called “fossil” because, just like rock fossils, they are made from dead plants and animals. Those plants and animals lived a very long time ago, even before dinosaurs. After they died, they were buried under layers of rock. The heat and pressure of being so far under the earth changed them until they became coal, oil and gas. We burn these three types of fuels to make light and heat, or to create other energy, such as electricity.

Oil is a sticky, black liquid made from tiny, one-celled sea plants and animals called plankton. To get to it, you have to drill a narrow hole deep into the earth and put in a pipe. Then it’s pumped up using suction, just like you suck your drink through a straw. Oil gets turned into gas to make your car go, tar for paving roads, kerosene for burning, and chemicals that make up plastic and other materials.

Anywhere you find oil, you will find natural gas. Just like with oil, you have to drill for natural gas and pump it into pipe lines. Then it has to be cleaned, which means everything but the methane gas is removed. Methane doesn’t have any smell, so a chemical is added to make it stink so you can tell when you’re around it. It’s highly flammable and is used for cooking, heating and making electricity. It’s cleaner than oil or coal and burns hotter as well, so it produces more electricity.

Coal is black, rocklike stuff that was created from dead plants in swamps. There is more of it than any other fossil fuel. Coal can be found near the surface of the earth or further underground. If it is near the surface, workers reach it by removing the layer of soil on top of it in a process called strip mining. If it is far underground, they dig deep tunnels to get to it. Forty percent of the electricity in the world is made from burning coal; its heat turns water into steam, which turns turbines -- big wheels -- that make the electricity.