There is no single underground economy; there are many. These underground economies are omnipresent, existing in market oriented as well as in centrally planned nations, be they developed or developing. Those engaged in underground activities circumvent, escape or are excluded from the institutional system of rules, rights, regulations and enforcement penalties that govern formal agents engaged in production and exchange. Different types of underground activities are distinguished according to the particular institutional rules that they violate. Five specific underground economies can be identified: