A conceptual framework

Social norms are widely accepted, informal, typically unspoken and unwritten rules of acceptable, appropriate, and obligatory behavior. They are often implicit, to the point where people internalize, accept, and follow them without critical thought. 

Social norms are strongly linked to, but different from, behavior: they govern a behavior but are not the behavior itself. As such, they are shared “behavioral rules” or shared expectations held by a set of people as to how people should behave.