Social identity is the portion of an individual's self-concept derived from perceived membership in a relevant social group. As originally formulated by social psychologists Henri Tajfel and John Turn
Social scientist William Graham Sumner
Henri Tajfel suggests that soldiers of opposing armies, fighting outside of view, is an illustrative example of behaviour at the extreme intergroup end of the intergroup–interpersonal continuum (shown: U.S. Marines in Fallujah, 2004).
The "black is beautiful" movement and the associated African American embrace of African hairdos (like afros), culture, traditions, and music was provided by Tajfel and colleagues as an example of the cognitive creativity of low-status groups in the face of stable intergroup relations (shown: Lauryn Hill, 2005).
In social psychology and sociology, an in-group is a social group to which a person psychologically identifies as being a member. By contrast, an out-group is a social group with which an individual d
Social identity theory
…it was found that under certain conditions individuals would endorse resource distributions that would maximize the positive distinctiveness of an in-group in contrast to an out-group at the expense of personal self-interest. Social identity matters because it shapes people's self-perceptions and interpersonal…
Multiple layers of in-groups and out-groups in an American football stadium: People in this stadium form an in-group of American football fans and professionals vs. those who are not fans of the sport. Fans in attendance at the stadium vs. people spectating the match via external means, e.g. television/radio coverage. Fans and professionals affiliated with one team vs. those affiliated with the opposing team. Professionals on the field (players, officials, coaches, mascots and cheerleaders) vs. the paying customers in the stands who are denied access to the facility's secure nucleus except by invitation from a high-status individual.