This volume for the first time brings together and comprehends in a new way all the information currently available in the domestic and world literature about the structure, physiology and functional purpose of human skin as a unique organ, second after the brain in terms of complexity and physiological significance for the body. Moreover, all data are considered from the standpoint of dividing the skin into individual structural and functional elements and main components. Acquaintance with the presented materials allows you to move away from the simplified canonical stylized idea of ​ ​ human skin as a kind of three-component structure with a certain set of functions, and more fully and accurately assess its unique, functional capabilities in natural conditions. All this knowledge is the initial base, without which it is impossible to proceed with the assessment, and even more so to the treatment of a particular skin pathology. The book is intended for dermatologists and dermatocosmetologists, as well as doctors of other specialties and inquisitive students.