This is the first monograph in Soviet aesthetic science specifically devoted to the analysis of the internal structure of the art world. The book consists of three parts. The first part, historiographic and methodological, examines the history of the study of this problem in world aesthetic thought, from ancient times to the present day. The second part, historical, shows how various types of art crystallized during the development of art culture and how they interacted to form new, synthetic arts. The third part, theoretical, explores the laws of the internal structure of the entire art world - the relationship of different classes, families, types and varieties of art, as well as genera and genres. The reader should, of course, take into account that the insufficient development of this topic in our science makes some provisions of the study debatable.