Internal combustion engines are among the most fascinating and ingenious machines which, with their invention and continuous development, have positively influenced the industrial and social history during the last century, especially by virtue of the role played as propulsion technology par excellence used in on-road private and commercial transportation. Nowadays, the growing attention towards the de-carbonization opens up new scenarios, but IC engines will continue to have a primary role in multiple sectors: automotive, marine, off- road machinery, mining, oil & gas and rail, power generation, possibly with an increasing use of non-fossil fuels. The book is organized in monothematic chapters, starting with a presentation of the general and functional characteristics of IC engines, and then dwelling on the details of the fluid exchange processes and the definition of the layout of intake and exhaust systems, obviously including the supercharging mechanisms, and continue with the description of the injection and combustion processes, to conclude with the explanation of the formation, control and reduction of pollutant emissions and radiated noise.