Social norms are the behavioral expectations and cues within a society or group. This sociological term has been defined as "the rules that a group uses for appropriate and inappropriate values, beliefs, attitudes and behaviors. These rules may be explicit or implicit. Failure to follow the rules can result in severe punishments, including exclusion from the group." They have also been described as the "customary rules of behavior that coordinate our interactions with others."
The social norms indicate the established and approved ways of doing things, of dress, of speech and of appearance. These vary and evolve not only through time but also vary from one age group to another and between social classes and social groups. What is deemed to be acceptable dress, speech or behavior in one social group may not be accepted in another.
Deference to the social norms maintains one's acceptance and popularity within a particular group; ignoring the social norms risks one becoming unacceptable, unpopular or even an outcast from a group. Social norms tend to be tacitly established and maintained through body language and non-verbal communication between people in their normal social discourse.
We soon come to know when and where it is appropriate to say certain things, to use certain words, to discuss certain topics or wear certain clothes, and when not to. Such knowledge about cultural norms is important for impression management, which is an individual's regulation of their nonverbal behaviour. We also come to know through experience what types of people we can and cannot discuss certain topics with or wear certain types of dress around. Mostly this knowledge is derived experientially.