In the U.S., credit unions have a clear organizational structure. All credit unions belong to one or the other parent credit union (there are 35 of them in the U.S.). Most modern credit unions represent specialized consumer cooperatives of citizens associated by the principle of social community: place of work, place of residence, profession, or any other shared interest. Credit unions also differ from the traditional consumer cooperatives. The uniqueness of credit unions is that they put together the principles and benefits of financial cooperatives, consumer cooperatives and mutual aid funds, born once by trade unions. Specialization of credit unions to provide financial services to its shareholders requires a particularly strict regulation of membership and acceptable activities. First central bank of credit unions appeared in 1876. Credit unions began to appear rapidly in many European countries. The main activities of credit unions, aimed at the organization of mutual aid and social support of citizens is not intended to profit. Credit unions historically formed as a special form of social support, initially taken upon themselves the social mission of protecting the interests of citizens in the field of financial services. Unlike banks credit unions limit their activities to a closed circle of people.