A credit union is a cooperative financial institution that is owned and controlled by its members. Credit unions differ from other financial institutions (banks, savings and loan, etc.) in that the members who have accounts in the credit union are the credit union's owners.

Credit union policies governing interest rates and other matters are set by a volunteer Board of Directors elected by and from the membership itself. Only a member of a credit union may deposit money with the credit union, or borrow money from it. As such, credit unions have historically marketed themselves as providing superior member service and being committed to helping members improve their financial health.

Credit unions may be viewed as non-profit organizations, or alternatively as for-profit enterprises charged with making a profit for their members (who receive any profits earned by the cooperative in the form of dividends paid on savings, which are taxed as ordinary income, or reduced interest rates on loans). This debate reflects credit unions' unusual organizational structure, which attempts to solve the principal-agent problem by ensuring the owners and the users of the institution are the same people. In any case credit unions generally cannot accept donations and must be able to prosper in a competitive market economy.