This book covers the fundamental topics of heat and mass transfer in a clear and concise manner, making it suitable for engineering courses across various disciplines. Designed for introductory courses, it also provides sufficient depth for advanced studies. The text divides the subjects into their fundamental forms: conduction, convection, and thermal radiation for heat transfer, and mass diffusion and convection for mass transfer. Reflecting typical engineering curricula, the book dedicates the first eleven chapters to heat transfer, while the final chapter focuses on mass transfer to maintain thematic continuity. Chapter 1 introduces heat and mass transfer phenomena, followed by Chapter 2, which addresses one-dimensional heat conduction in steady state. Chapter 3 extends this to two- and three-dimensional geometric situations, including numerical solution methods. Transient heat conduction for simple systems and complex geometries is discussed in Chapter 4 using analytical and numerical techniques. Chapters 5 and 6 explore forced convection of heat on external and internal surfaces, respectively, while Chapter 7 focuses on natural (free) convection. Phase change heat transfer, including condensation and vaporization, is the subject of Chapter 8. Chapter 9 delves into the thermal design of heat exchangers. Thermal radiation is covered in Chapters 10 and 11, with the former addressing fundamentals and the latter focusing on engineering applications and form factor theory. Finally, Chapter 12 discusses mass diffusion and convection. This work reflects the authors' extensive experience teaching heat and mass transfer. The first author has over 30 years of teaching experience in the field. The book includes numerous solved and proposed problems, many derived from real test questions.