The emotions that human beings experience play a fundamental role in all social phenomena. As a result, sociology needs to incorporate the analysis of affective structures and emotional dynamics into its objects of study. The integration of feelings, affects, moods and emotional states into sociological research, which began four decades ago with the birth of the sociology of emotions, must continue advancing until emotions are fully integrated into the general sociological perspective. This article offers an introductory and critical overview of the work sociologists of emotions have carried out so far. They have helped us, first of all, to understand what an emotion is, the countless number of existing feelings, and the great complexity of emotional processes. Second, they have revealed the social nature of human emotions, and the emotional nature of social phenomena. Third, they have developed a number of theoretical approaches to studying the emotions. And, lastly, they have carried out sociological analyses of many specific emotions (fear, trust, shame, etc.), and emotional analyses in many areas of sociology (gender, work, organizations, social movements, etc.). This article also offers suggestions for the future development of the sociology of emotions, and a selected and updated bibliography.