The book "The Great Importance of Refrigeration and Air Conditioning Technology" lies in its applications. In Germany, approximately 15% of the consumed electricity is attributed solely to this sector. The foundation of this book is based on the author's lecture notes at the European Academy of Studies in Refrigeration, Air Conditioning, and Ventilation in Maintal. The theoretical basis of the disciplines of refrigeration and air conditioning technology is Technical Thermodynamics, without which a deeper understanding of refrigeration and air conditioning processes is not possible, and this is introduced here. Following this introductory chapter, the components and processes of refrigeration and air conditioning system technology are described in detail. Fifty extensive example problems allow for the practical application of the presented theory. Thus, this textbook and exercise book serves as the basis for the design of refrigeration and air conditioning systems.