A social norm or norm is a shared standard of acceptable behavior by a group. Social norms can both be informal understandings that govern the behavior of members of a society, as well as be codified into rules and laws. Social normative influences or social norms, are deemed to be powerful drivers of human behavioural changes and well organized and incorporated by major theories which explain human behaviour. Institutions are composed of multiple norms. Norms are shared social beliefs about behavior; thus, they are distinct from "ideas", "attitudes", and "values", which can be held privately, and which do not necessarily concern behavior. Norms are contingent on context, social group, and historical circumstances.
Scholars distinguish between regulative norms (which constrain behavior), constitutive norms (which shape interests), and prescriptive norms (which prescribe what actors ought to do). The effects of norms can be determined by a logic of appropriateness and logic of consequences; the former entails that actors follow norms because it is socially appropriate, and the latter entails that actors follow norms because of cost-benefit calculations. Others see social norms emerging as part of an evolutionarily stable strategy, where they stabilize through third-party punishment.
