Norms are cultural products (including values, customs, and traditions) which represent individuals' basic knowledge of what others do and think that they should do.Sociologists describe norms as informal understandings that govern individuals' behavior in society. On the other hand, social psychology has adopted a more general definition, recognizing smaller group units, such as a team or an office, may also endorse norms separate or in addition to cultural or societal expectations. In other words, norms are regarded to exist as collective representations of acceptable group conduct as well as individual perceptions of particular group conduct.

Furthermore, in the field of social psychology, the roles of norms are emphasized which can guide behavior in a certain situation or environment as "mental representations of appropriate behavior". For example, it has been shown that normative messages can promote pro-social behavior, including decreasing alcohol use and increasing voter turnout. According to the psychological definition of social norms' behavioral component, norms have two dimensions: how much a behaviour is exhibited, and how much the group approves of that behavior. Both of these dimensions can be used in normative messages to alter norms and subsequently alter behaviors; for example, a message can target the former dimension by describing high levels of voter turnout in order to encourage more turnout. At the same time, norms also can be changed contingent on the observed behavior of others (how much behavior is exhibited). In fact, in Sherif (1936), one confederate was able to affect the development of a group norm related to the autokinetic effect.