社会认同是由一个人的团体成员定义的自我的一部分。社会认同理论由社会心理学家亨利·塔菲尔特（Henri Tajfel）和约翰·特纳（John Turner）在20世纪70年代提出，描述了社会认同变得比个人身份更重要的条件。该理论还规定了社会认同可以影响群体间行为的方式。社会认同理论起源于Henri Tajfel的早期作品，该作品探讨了感性过程导致社会刻板印象和偏见的方式。这引发了Tajfel及其同事在20世纪70年代早期进行的一系列研究，这些研究被称为最小组研究。在这些研究中，参与者被任意分配到不同的群体。然而，尽管他们的团体成员没有意义，但研究表明参与者倾向于他们被分配到的团体 – 他们的团体 – 而不是团体成员，即使他们没有从团体成员中获得个人利益而且没有与任何一组成员的历史。研究表明，群体成员资格非常强大，只需将人们分组，就足以让人们从群体成员身份来考虑自己。此外，这种分类导致了群体偏袒和群体外歧视，这表明群体之间没有任何直接竞争可能存在群体间冲突。在这项研究的基础上，Tajfel在1972年首次定义了社会认同的概念。社会认同的概念被创建为一种考虑基于一个人所属的社会群体概念化自我的方式。然后，Tajfel和他的学生约翰特纳在1979年介绍了社会认同理论。该理论旨在阐明引导人们定义他们的群体成员的认知过程和通过有利地比较他们的社会群体使人们保持积极的社会认同的动机过程。到其他团体。社会认同理论规定了个人进行组内/组外分类的三个心理过程。第一个过程，即社会分类，是我们将个人组织成社会群体以理解我们的社会世界的过程。这个过程使我们能够根据我们所属的群体来定义人，包括我们自己。我们倾向于根据他们的社会类别来定义人，而不是他们的个人特征。社会分类通常导致强调同一群体中人们的相似性以及不同群体中人们之间的差异。一个人可以属于各种社会类别，但根据社会环境，不同的类别或多或少都很重要。例如，一个人可以将自己定义为商业主管，动物爱好者和忠诚的阿姨，但这些身份只有在与社会情境相关时才会出现。第二个过程，即社会认同，是识别为小组成员。与群体进行社交认同会导致个人表现出他们认为该群体成员应该表现的方式。例如，如果一个人将自己定义为环境保护主义者，她可能会尝试节约用水，尽可能回收利用，并在气候变化意识的集会中进行游行。通过这个过程，人们在情感上投入到他们的团队成员中。因此，他们的自尊受到他们团体地位的影响。
Social identity is the part of the self that is defined by one’s group memberships. Social identity theory, which was formulated by social psychologist Henri Tajfel and John Turner in the 1970s, describes the conditions under which social identity becomes more important than one’s identity as an individual. The theory also specifies the ways in which social identity can influence intergroup behavior. Social identity theory arose from Henri Tajfel’s early work, which examined the way perceptual processes resulted in social stereotypes and prejudice. This led to a series of studies that Tajfel and his colleagues conducted in the early 1970s that are referred to as minimal-group studies. In these studies, participants were arbitrarily assigned to different groups. Despite the fact that their group membership was meaningless, however, the research showed that participants favored the group they were assigned to — their in-group — over the out-group, even if they received no personal benefits from their group membership and had no history with members of either group. The studies demonstrated that group membership was so powerful that simply classifying people into groups is enough to make people think of themselves in terms of that group membership. Furthermore, this categorization led to in-group favoritism and out-group discrimination, indicating that intergroup conflict could exist in the absence of any direct competition between groups. On the basis of this research, Tajfel first defined the concept of social identity in 1972. The concept of social identity was created as a means to consider the way one conceptualizes the self based on the social groups to which one belongs. Then, Tajfel and his student John Turner introduced social identity theory in 1979. The theory aimed to illuminate both the cognitive processes that lead people to define their group memberships and the motivational processes that enable people to maintain positive social identity by favorably comparing their social group to other groups. Social identity theory specifies three mental processes individuals go through to make in-group/out-group classifications. The first process, social categorization, is the process by which we organize individuals into social groups in order to understand our social world. This process enables us to define people, including ourselves, on the basis of the groups to which we belong. We tend to define people based on their social categories more often than their individual characteristics. Social categorization generally results in an emphasis on the similarities of people in the same group and the differences between people in separate groups. One can belong to a variety of social categories, but different categories will be more or less important depending on social circumstances. For example, a person can define themselves as a business executive, an animal lover, and a devoted aunt, but those identities will only come up if they are relevant to the social situationThe second process, social identification, is the process of identifying as a group member. Socially identifying with a group leads individuals to behave in the way that they believe members of that group should behave. For instance, if an individual defines herself as an environmentalist, she may try to conserve water, recycle whenever possible, and march in rallies for climate change awareness. Through this process, people become emotionally invested in their group memberships. Consequently, their self-esteem is impacted by the status of their groups.