This book is designed for B.Sc., B.E. and A.M.I.E. students of all discipline. It lays priority to the basic concepts of the topic with developing a profound conceptual base of heat and thermodynamics. This book is a bridge between thermal physics and non-equilibrium physics. It contains both the basic theory and principles as well as topics like fundamental concepts of kinetic theory and transport phenomena, heat and thermodynamics, ideal gases, real gases, laws of thermodynamics and heat engines, entropy, black body radiation and laws of emission and absorption of radiation, thermodynamic relations and various phenomena of day-to-day life.