Coal is a type of black rock, made almost entirely of carbon. It is formed from old plant matter being squashed by the gradual movement of the earth over a very long time. Coal can be burnt, and is often used as the fuel for power plants. Coal is dug out of the ground, from coal mines. Coal is not the same as charcoal, which is just the black residue after wood is burnt.
Coke is a fuel formed by burning coal or wood. If you are looking for the drink, see cola. It is also a slang word for cocaine.
Firewood is wood that has been collected just to be burnt as fuel. Firewood is usually cut into small pieces so it can fit inside a fireplace.
Fuel is something that can be turned into energy. Firewood, coal and gasoline are all fuels that can be burnt to produce fire and heat. Uranium is fuel in a nuclear reactor. Food is fuel for people.
Gasoline, also called petrol in some countries, is a toxic liquid that is used as a fuel in internal combustion engines. Many kinds of vehicle use gasoline to make them run.
Kerosene is a liquid fuel that can be used for a variety of things. It is often used as the fuel in oil lamps, for heating in houses, and as a fuel for small engines or even some kinds of aircraft.
Paraffin is the name given to a range of fuel oils, also called kerosene in some countries. The form of paraffin most people are familiar with is paraffin wax, which is used to make candles from.
Peat is partly decayed plant matter that collects in places like moors and bogs. Peat is dug up and harvested as a fuel in some parts of the world.