Etiquette, system of rules and conventions that regulate social and professional behavior. In any social unit there are accepted rules of behavior upheld and enforced by legal codes; there are also norms of behavior mandated by custom and enforced by group pressure. An offender faces no formal trial or sentence for breach of etiquette; the penalty lies in the disapproval of other members of the group. Regardless of its level of material culture, any highly stratified society will possess an etiquette in which every person knows the behavior expected from him toward others and from others toward himself.
Source: Encyclopædia Britannica