This course deals with the basics of Internal Combustion engines, the combustion phenomenon in both spark ignition and compression ignition engines. Various emission control technologies that includes In-cylinder treatment and exhaust treatment is also discussed in this course. The first lecture on basics of I C engines covers the classification and the components used in construction of engines. It also includes working of two stroke and four stroke engines. The second and third lecture, that deals with normal as well as abnormal combustion in S I and C I engines covers the working of four stroke petrol and diesel engines and the phases of combustion that are observed in S I and C I engines. The terms like Ignition lag and delay period and their effect on combustion is also discussed. The theory of detonation and knocking which is the cause of abnormal combustion and the parameters affecting this tendency are also well explained. The parameters used in designing SI and CI engines are also included in this lectures. The technologies like Turbocharging, Catalytic convertor , regenerative particulate filtration and other emission reduction technologies are discussed in fourth lecture. The fifth lecture covers working of common rail injection system that directly affects the combustion phenomenon in CI engines. The effect of high pressure that gives fine atomization and the multiple injection strategy and its advantage is also discussed in this session.