An internal combustion engine (IC engine) refers to a type of heat engine wherein the combustion of fuel occurs with the help of an oxidizer in the combustion chamber, which is a significant part of the working fluid circuit. The expansion of the high-pressure and high-temperature gases generated through combustion puts direct force on certain components of an IC engine. Usually, the force is applied to turbine blades, pistons, a nozzle, or a rotor. The component is moved across a distance by this force, which converts chemical energy into kinetic energy, which is further utilized to propel, power or move whatsoever the engine is coupled with. This book is compiled in such a manner, that it will provide an in-depth knowledge about the theory and working of the internal combustion engine. The various advancements in these engines are glanced at and their applications as well as ramifications are looked at in detail. Those in search of information to further their knowledge will be greatly assisted by this book.