The book "Mass Psychology and Ego Analysis" by the outstanding Austrian psychoanalyst Sigmund Freud is one of his most important works, in which he examines the phenomena and patterns that arise in mass groups of people. The author examines the influence of the collective unknown on the individual, explains the mechanisms of formation and functioning of mass complexes and ideas. In the book, Freud also proposed the method of analysis as a way of revealing mental conflicts and contradictions in a person. "Mass Psychology and the Analysis of the Self" is considered a classic work of psychoanalysis, which helps to better understand the behavior of a person in a group and the relationship between individuals in a team.