Fuel
Fuel explained in an easy to understand way:
Imagine you're trying to start a campfire with damp wood, and it takes forever to catch fire and produce heat. This situation is similar to how certain materials, like dry wood, coal, or oil, are much more efficient energy sources because they have a higher ability to release energy when ignited. Just like how dry wood is easier to burn and provides more warmth, fuels like coal or oil are rich in energy content, making them effective at releasing energy quickly and efficiently when burned.
Practice Version
Fuel: A material that releases energy when burned, like wood, coal or oil. Fuel. Fuel is a substance that provides energy when it undergoes a chemical reaction, such as burning.