Thermodynamics is a comprehensive guide that explores the fundamental laws governing energy, heat, and work, and their vital applications in science and engineering. This book presents a balanced blend of theory, practical examples, and problem-solving techniques, making it an essential resource for students, educators, and professionals alike. Starting from the basic concepts and the laws of thermodynamics, the text gradually progresses to advanced topics, including cycles, energy systems, and real-world engineering applications. Each chapter is supported with clear explanations, illustrative diagrams, solved examples, and exercises designed to strengthen understanding and application skills. Special emphasis is placed on connecting theoretical principles to practical engineering challenges in fields such as power generation, refrigeration, air conditioning, renewable energy, and industrial processes. The book also integrates modern computational approaches, highlighting the evolving role of technology in thermodynamic analysis. Whether used as a textbook for academic courses or as a reference for professionals, this book aims to simplify learning while maintaining rigor and depth. With its structured approach, accessible style, and focus on both fundamentals and applications, Thermodynamics serves as a reliable companion for anyone seeking to master this cornerstone of engineering science.