This book is written to cover a specific curriculum on the subject of thermodynamics and thermal physics. The book provides a self-study-based way to the students and gives an organizing set of ideas on various topics of the study. Significant examples and applications are given for better insights into the topics of the study. The text gives necessary mathematical methods and tools to explain concepts and theories. This textbook also contains undergraduate/ graduate-level teaching elements. The book is meant to be a textbook for undergraduate and postgraduate students of physics and engineering at most Indian Universities. The book will also serve as a reference book for integrated graduate courses in physics and Photonics.