This is a comprehensive book on Internal Combustion Engines for mechanical and automobile engineering undergraduates. It comprises of a breakdown explanation of all the parts that make up an Internal Combustion Engine and details the theory behind their working. Self explanatory sketches, graphs, line schematics of processes and tables along with illustrated examples, exercises and problems at the end of each chapter help in practicing the application of the basic principles presented in the text. The book factors in the various parameters that go into selection of a four-stroke and two-stroke engine, putting the reader eye-to-eye with automobile enthusiasts to understand the working of engines. In addition to the specifics, the book brings the reader up to speed with the latest developments that have taken place in the last few decades in relation with the automobile industry. This book can be used for refresher courses for professionals in automobile industries.