Group has been defined as two or more people who interact with one another, share similar characteristics, and collectively have a sense of unity. Other theorists disagree however, and are wary of definitions which stress the importance of interdependence or objective similarity. Instead, researchers within the social identity tradition generally define it as "a group is defined in terms of those who identify themselves as members of the group". Regardless, social groups come in a myriad of sizes and varieties. For example, a society can be viewed as a large social group.

Social norms, or mores, are the unwritten rules of behavior that are considered acceptable in a group or society. Norms function to provide order and predictability in society. On the whole, people want approval, they want to belong, and those who do not follow the norms will suffer disapproval or may even be outcast from the group. This is how we keep society functioning, not just with direct rules but also expectations. When