Euro cheques, electronic transfers, banking, etc.) at midnight on 1 January 1999, when the national currencies of participating countries (the eurozone) ceased to exist independently. Their exchange rates were locked at fixed rates against each other. The euro thus became the successor to the European Currency Unit (ECU). The notes and coins for the old currencies, however, continued to be used as legal tender until new euro notes and coins were introduced on 1 January 2002. The changeover period during which the former currencies' notes and coins were exchanged for those of the euro lasted about two months, until 28 February
De facto currency De facto currency A de facto currency is a unit of money that is not legal tender in a country but is treated as such by most of the populace. The United States dollar and the European Union euro are the most common de facto currencies. Andorra used the euro unofficially prior to June 2013, at which point the euro became its official currency. The euro remains the de facto currency in Kosovo and Montenegro. Countries using the United States dollar as their de facto currency include Aruba and Cambodia, where most hotels, restaurants, and transportation are priced in dollars;