Complementary currency
A complementary currency, or alternative currency, is a medium of exchange that is accepted in much the same way as a regular currency, within a group of people or a geographical area. It is made to complement a national currency. Usually complementary currencies are not legal tender, they cannot be used in exactly the same way as money.  Their use is based on all the people of the group agreeing to accept them.  According to Jérôme Blanc of Laboratoire d'Économie de la Firme et des Institutions, complementary currencies aim to protect, stimulate or orientate the economy. They may also be used to advance particular social, environmental, or political goals.