Biodiesel is a type of renewable fuel made from vegetable oils, animal fats, or recycled restaurant greases. It is a cleaner-burning alternative to traditional diesel fuel, produced through a chemical process called transesterification. Biodiesel has gained popularity as a sustainable and environmentally-friendly fuel source that can help reduce greenhouse gas emissions and dependence on fossil fuels. Researchers in this area focus on developing more efficient production methods, investigating the environmental impacts of biodiesel production and use, and improving its performance and compatibility with existing diesel engines.