Thermodynamics is the science of heat and energy transfer, focusing on how energy is converted between different forms and affects matter. Key concepts include temperature, which measures thermal energy and entropy, which indicates disorder in a system. The first law of thermodynamics or energy conservation, ensures energy is efficiently transformed in engines, power plants and circuits. The second law, stating that energy transformations increase entropy, helps optimise efficiency and reduce energy losses, like minimising heat loss and improving batteries. The zeroth and third laws maintain stable temperatures, preventing devices from overheating. By applying these principles, better energy management solutions are created, system performance is improved and sustainable technologies are developed. This approach specifies systems are efficient, reliable and safe, making thermodynamics essential for designing engines, refrigerators and electronic devices. This book traces the progress of this field and highlights some of its key concepts and applications. It presents the complex subject of thermodynamics in the most comprehensible and easy to understand language. Through this book, we attempt to further enlighten the readers about the new concepts in this field.