The cooling methods that exist are described, especially the emphasis is on the vapor compression refrigeration system - which constitutes the main refrigeration system. Furthermore, the components of a refrigeration system are defined and the different types of refrigerants are analyzed. Later, the use of refrigeration in food preservation and the different applications of cold are explained. Finally, the sources of thermal loads and their influence on the selection of refrigeration equipment are analyzed. It should be added that this publication stands out for its detailed theoretical exposition for the development of solutions in the real world based on the care of our planet and of future generations.