We use social categories like black, white, Australian, Christian, Muslim, student, and busdriver because they are useful. Similarly, we find out things about ourselves by knowing what categories we belong to. We define appropriate behaviour by reference to the norms of groups we belong to, but you can only do this if you can tell who belongs to your group. The second important idea is identification . We identify with groups that we perceive ourselves to belong to.
Identification carries two meanings.
Part of who we are is made up of our group memberships. That is sometimes we think of ourselves as group members and at other times we think of ourselves as unique individuals. This varies situationally, so that we can be more or less a group member, depending upon the circumstances. What is crucial for our purposes is that thinking of yourselves as a group member and thinking of yourself as a unique individual are both parts of your self-concept. The first is referred to as social identity , the latter is referred to as personal identity .