A complementary currency is a currency or medium of exchange which is not a national currency, but which is thought of as supplementing or complementing national currencies. :3 :2 Complementary currencies are usually not legal tender and their use is based on agreement between the parties exchanging the currency. According to Jérôme Blanc of Laboratoire d'Économie de la Firme et des Institutions, complementary currencies aim to protect, stimulate or orientate the economy.:7 They may also be used to advance particular social, environmental, or political goals.:4 - wikipedia
When speaking about complementary currencies, a number of overlapping and often interchangeable terms are in use: local or community currencies are complementary currencies used within a locality or other form of community (such as business-based or online communities); regional currencies are similar to local currencies but used within a larger geographical region; and sectoral currencies are complementary currencies used within a single economic sector, such as education or health care. Many private currencies are complementary currencies issued by private businesses or organizations. Other terms include alternative currency, auxiliary currency, and microcurrency.
Some complementary currency activists are Belgian ex-banker Bernard Lietaer, British economist Hazel Henderson, Dutch STRO-director Henk van Arkel that developed Cyclos, Qoin initiators Edgar Kampers and Rob van Hilten, Margrit Kennedy from Monneta, Local Exchange and TRading (Local exchange trading system) inventor Michael Linton, Time Banking inventor Edgar S. Cahn, Complementary Currency Resource Center coordinator Stephen DeMeulenaere and many others - wikipedia
Lietaer has argued that the world's national currencies are inadequate for the world's business needs, citing how 87 countries have experienced major currency crashes over a 20-year period, and arguing for complementary currencies as a way to protect against these problems. Lietaer has also spoken at an International Reciprocal Trade Association (IRTA) conference about barter.