Prepared by filtering down lecture notes taught over many years in the Mechanical Engineering departments of Istanbul Technical University and Işık University, this work presents the fundamental laws and definitions of thermodynamics through a 12-week systematic education plan. Appealing to various engineering disciplines, primarily mechanical engineering, the work serves as a technical resource of international standards with its equivalent content prepared in both Turkish and English. The problems included at the end of each lecture to improve the student's analytical skills are supported by B.G. Kyle’s reference tables and enriched with answer keys. Blending theoretical depth with a pedagogical approach, this book is a reliable reference guide for both academic education and fundamental engineering applications.