A label is an abstract concept in sociology used to group people together based on perceived or held identity. Labels are a mode of identifying social groups. Labels can create a sense of community within groups, but they can also cause harm when used to separate individuals and groups from mainstream society. Individuals may choose a label, or they may be assigned one by others. The act of labeling may affect an individual's behavior and their reactions to the social world. Symbolic interactionism and labeling theory both examine labels as a social concept, and emphasize the social weight of labels and labeling. Symbolic interactionism focuses on expectations of social roles, while labeling theory focuses on the social and individual consequences of labeling. Both theories link between labels and contexts and maintain that their meanings are socially defined rather than universal. Labels serve many functions in sociology. They group individuals with common characteristics, such as academic performance, gender, race, or adherence to law. Labels are a product of their social context, and may not be applicable outside their context. For example, a society without a formal legal system may not have the label “criminal,” as there can be no stigmatization of crime in a society without laws. Labels are also be used to differentiate between groups for negative reasons. A label may be placed on someone to designate them as different from mainstream society. This can result in in-group favoritism and othering. In-group favoritism occurs when individuals in one group (united by one label) favor members of their group above outsiders. Othering is a specific form of labeling in which the label produces patterns of power and privilege by designating those who do not follow accepted social norms as lesser. In some cases, othering can cause social exclusion, in which case groups labeled as "other" are denied full participation in society. Labels have been used to alienate groups and justify unequal power dynamics, which can harm the individual experiencing exclusion and alienation.