The institutional perspective argues that interorganizational relationships are shapes as much by a company's need for legitimacy as by the need to provide products and services. The need for legitimacy means that the organization will adopt structures and activities that are perceived as valid, proper, and up to date by external stakeholders. In this way, established organizations copy techniques from one another and begin to look very similar. The emergence of common structures and approaches in the same field is called institutional similarity or institutional isomorphism. Three core mechanisms explain increasing organizational homogeneity: mimetic forces, which result from responses to uncertainty; coercive forces, which stem from power differences and political influences; and normative forces, which result from common training and professionalism.