 The most important aspect of the theory is that “social identity is what allows group behavior to occur at all.” (Haslam, 2012) Turner thought that the “self-system reflects the operation of a context-sensitive categorization process, in which people see themselves as either sharing category membership with others or not.” (Haslam, 2012) Turner's theory gives an insight into understanding “me vs. them” and “us vs. them”.It is a person's response to their personal life and their social life.This leads to the other important contribution of the theory is that it further explains shared social identity which Turner believed to be the basis for mutual social influence.