There is a lack of consensus in the literature, spanning multiple fields, on what exactly a norm is and furthermore on the characteristics differentiating types of norms. This paper provides definitions and a simple typology of norms with a focus on useful, objective distinctions. It is hoped that such a typology will add to the scientific rigor of communication, modeling, and clarity of thought on norms within economics and possibly other disciplines. The viability of “more complete” typologies, which often suffer from a lack of clear criteria for differentiating types of norms, is questioned. Two main properties of a norm are emphasized: (1) whether or not the behavior is simply what is done or whether it is what one should do, and (2) the source of sanctions for violating a norm, whether oneself, others, both or neither.