norm

1. Informal guideline about what is considered normal (what is correct or incorrect) social behavior in a particular group or social unit. Norms form the basis of collective expectations that members of a community have from each other, and play a key part in social control and social order by exerting a pressure on the individual to conform. In short, "The way we do things around here."

2. Formal rule or standard laid down by legal, religious, or social authority against which appropriateness (what is right or wrong) of an individual's behavior is judged.