This textbook teaches students the principles, materials, and applications they need to understand and analyze heat transfer problems they will encounter in practice. The emphasis on modern practical problems (including thermoelectric cooling), in the numerous examples, sets this work apart from other available works. The approach is to discuss heat transfer problems (in search of innovative and optimal solutions) and the engineering analysis, to motivate fundamental principles and analytical problem solving methods. By introducing heat flux tracking, the students develop intuition about the central role of heat transfer in engineered systems. The energy conversion mechanisms (to and from thermal energy) are integrated into the treatment, thus allowing for realistic design of thermal systems. Note that microscale heat carriers are also covered. Those familiar with the first version of this book from another publisher will notice that this volume is shorter and the generic problem solving engine was replaced by MATLAB software. The rich materials removed from the print version are available on the web site, www.cambridge.org/kaviany. A complete solutions manual for the numerous exercises is available to qualified instructors.