Biodiesels are fuels that are produced using various natural materials that are readily available on earth. In the current situation, the safest substitute for fossil fuels such as diesel used in the automotive industry is considered to be biodiesel. Biodiesel can be derived from various sources, such as animal oil, fruits, seeds, etc., and can meet the industry's needs. This book presents numerous works that consider the use of biodiesel, its blends and the effect on the efficiency and emission of the IC engine. While biofuels show less efficiency than pure diesel, they are highly functional because they also help to save the environment by releasing less toxic gases. The focus of the study is on biodiesel and the various aspects of its effects on energy usage and the climate. Several studies are being taken into account here and then organized into a system investigating four different aspects of biodiesel in such a way as to study the origin and final application of biodiesel. By using DIESEL-RK simulation program, the current study uses cotton seed oil, Mahua oil, Tallow oil as well as yellow grease oil for study purposes.