The heat engine where the combustion of a fuel occurs with an oxidizer inside a combustion chamber is known as internal combustion engine. Inside an internal combustion engine, the combustion produces the expansion of the high-temperature and high-pressure gases. This applies direct force to some components of the engine such as turbine blades, pistons, rotor or nozzle. This force moves the components to a distance by transforming chemical energy into mechanical energy. Internal combustion engine can be classified into reciprocating, rotary and continuous combustion. The reciprocating piston engines are the most commonly used engines for land and water vehicles. Rotary engines are used in some aircraft, automobiles and motorcycles. The topics included in this book on internal combustion engine are of utmost significance and bound to provide incredible insights to readers. It outlines the processes and applications of such engines in detail. Those in search of information to further their knowledge will be greatly assisted by this book.