Fuel is a substance that provides energy through combustion or chemical reactions. It is essential for powering vehicles, generating electricity, and heating homes. Common types of fuel include gasoline, diesel, and natural gas, which are derived from fossil fuels formed over millions of years from ancient organic matter. In addition to fossil fuels, there are alternative fuels such as biofuels and hydrogen that are gaining popularity due to their potential to reduce environmental impact. The transition to cleaner energy sources is crucial for addressing climate change and promoting sustainability in our energy systems.