The book presents a lucid and systematic exposition of the fundamental principles of Thermal Physics. The discussion is divided into three parts: (a) Kinetic Theory (b) Thermodynamics and (c) Statistical Mechanics. The treatment of the subject matter is rigorous while still retaining a student-friendly approach. Key features Special attention and coverage of topics like Maxwellian distribution transport phenomena and entropy and their application to various physical systems. Detailed discussion on the important topic of `Random Walk? that provides models for numerous application like Brownian motion. Wide variety of solved examples and unsolved exercises at the end of each chapter. Use of Mnemonics (the technique of improving the memory) demonstrated to help students memorise various expressions. With its comprehensive coverage and selection of choice numerical examples, the book will serve as an indispensable text for undergraduate students of Physics.