You are about to begin the study of one of the most general and fascinating subjects inscience-thermodynamics, the science that deals with energy and its relation to matter. Thermo-dynamics is most general because every technological system involves the utilization of energy and matter. In fact, since engineering thermodynamics plays such a vital role in the design of so many processes, devices, and systems for use in the home as well as in industry, it is no exaggeration to say that it touches our daily life. Engineering thermodynamics is also very important in our search for solutions to problems in connection with energy crises, shortages of fresh water, air pollution, and garbage disposal in the cities. In short, engineering thermodynamics is most relevant in our search for a better quality of life.