Fuels can be categorized into two main types: renewable and non-renewable. Renewable fuels, such as solar energy, wind energy, and biofuels, are derived from natural processes and can be replenished over time. These fuels are considered more environmentally friendly as they produce fewer greenhouse gas emissions. Non-renewable fuels, including coal, oil, and natural gas, are formed from ancient organic materials and are finite resources. Once depleted, they cannot be replaced within a human timescale. These fuels are commonly used for electricity generation, heating, and powering vehicles, but their extraction and use contribute to environmental pollution and climate change.