The Crowd: A Study of the Popular Mind is a classic book in the field of social psychology. Since its publication in 1895, it has been translated into about 20 languages. In this book, the author examines the unique psychology of crowds, and in particular makes a penetrating comparative analysis of the different psychological characteristics between individuals and crowds. The problems discussed in this book, written a hundred years ago, are still relevant to a lot of people today. Why is the “irrationality” of crowds often unbelievable and difficult to understand? We may find the answers to our confusions in this book.