The article reviews different catalysts used to make biodiesel (methyl esters) better and more efficiently. Heterogeneous catalysts, especially, are great for making biodiesel in a green way because they are very active, stable, and can be used multiple times. These catalysts are important for turning cheap, non-food materials into biodiesel under mild conditions. The study also looks at how biodiesel performs in different applications and how catalysts can improve its production.