The euro is the official currency of 20 of the 27 member states of the European Union. This group of states is officially known as the euro area or, more commonly, the eurozone. The euro is divided into 100 euro cents.
There are eight euro coin denominations, ranging from one cent to two euros. The coins first came into use in 2002. They have a common reverse, portraying a map of Europe, but each country in the eurozone has its own design on the obverse, which means that each coin has a variety of different designs in circulation at once. Four European microstates that are not members of the European Union use the euro as their currency and also have the right to mint coins with their own designs on the obverse side.
The euro area, commonly called the eurozone (EZ), is a currency union of 20 member states of the European Union (EU) that have adopted the euro (€) as their primary currency and sole legal tender, and have thus fully implemented EMU policies.
The European Exchange Rate Mechanism (ERM II) is a system introduced by the European Economic Community on 1 January 1999 alongside the introduction of a single currency, the euro as part of the European Monetary System (EMS), to reduce exchange rate variability and achieve monetary stability in Europe.
The European System of Central Banks (ESCB) is an institution that comprises the European Central Bank (ECB) and the national central banks (NCBs) of all 27 member states of the European Union (EU). Its objective is to ensure price stability throughout the EU, and improve monetary and financial cooperation between eurozone and non-eurozone member states of the EU.
The European Union has a number of relationships with foreign states. According to the European Union's official site, and a statement by Commissioner Günter Verheugen, the aim is to have a ring of countries, sharing EU's democratic ideals and joining them in further integration without necessarily becoming full member states.
A currency union is an intergovernmental agreement that involves two or more states sharing the same currency. These states may not necessarily have any further integration.
Romania's national currency is the leu. After Romania joined the European Union (EU) in 2007, the country became required to replace the leu with the euro once it meets all four euro convergence criteria, as stated in article 140 of the Treaty on the Functioning of the European Union. As of 2023, the only currency on the market is the leu and the euro is not yet used in shops. The Romanian leu is not part of the European Exchange Rate Mechanism, although Romanian authorities are working to prepare the changeover to the euro. To achieve the currency changeover, Romania must undergo at least two years of stability within the limits of the convergence criteria.
The 2 euro coin (€2) is the highest-value euro coin and has been used since the introduction of the euro in 2002. The coin is used in 22 countries with a collective population of about 341 million. The coin is made of two alloys: the inner part of nickel brass, the outer part of copper-nickel. All coins have a common reverse side and country-specific national sides. The coin has been used since 2002, with the present common side design dating from 2007.
Sweden does not currently use the euro as its currency and has no plans to replace the existing Swedish krona in the near future. Sweden's Treaty of Accession of 1994 made it subject to the Treaty of Maastricht, which obliges states to join the eurozone once they meet the necessary conditions. Sweden maintains that joining the European Exchange Rate Mechanism II, participation in which for at least two years is a requirement for euro adoption, is voluntary, and has chosen to remain outside pending public approval by a referendum, thereby intentionally avoiding the fulfilment of the adoption requirements.
The euro came into existence on 1 January 1999, although it had been a goal of the European Union (EU) and its predecessors since the 1960s. After tough negotiations, the Maastricht Treaty entered into force in 1993 with the goal of creating an economic and monetary union (EMU) by 1999 for all EU states except the UK and Denmark.
The United Kingdom did not seek to adopt the euro as its official currency for the duration of its membership of the European Union (EU), and secured an opt-out at the euro's creation via the Maastricht Treaty in 1992, wherein the Bank of England would only be a member of the European System of Central Banks.
Denmark uses the krone as its currency and does not use the euro, having negotiated the right to opt out from participation under the Maastricht Treaty of 1992. In 2000, the government held a referendum on introducing the euro, which was defeated with 53.2% voting no and 46.8% voting yes. The Danish krone is part of the ERM II mechanism, so its exchange rate is tied to within 2.25% of the euro.
Montenegro is a country in South-Eastern Europe, which is neither a member of the European Union (EU) nor the Eurozone; it does not have a formal monetary agreement with the EU either. However, it is one of the two territories that has unilaterally adopted the euro in 2002 as its de facto domestic currency. This means that even though the euro is not a legal tender there, it is treated as such by the government and the population.
The enlargement of the eurozone is an ongoing process within the European Union (EU). All member states of the European Union, except Denmark which negotiated an opt-out from the provisions, are obliged to adopt the euro as their sole currency once they meet the criteria, which include: complying with the debt and deficit criteria outlined by the Stability and Growth Pact, keeping inflation and long-term governmental interest rates below certain reference values, stabilising their currency's exchange rate versus the euro by participating in the European Exchange Rate Mechanism, and ensuring that their national laws comply with the ECB statute, ESCB statute and articles 130+131 of the Treaty on the Functioning of the European Union. The obligation for EU member states to adopt the euro was first outlined by article 109.1j of the Maastricht Treaty of 1992, which became binding on all new member states by the terms of their treaties of accession.
Kosovo adopted the euro as its de facto legal tender in 2002 despite the territory not being a member of the Eurozone or the European Union. This succeeded its use of German marks from 1999.
The international status and usage of the euro has grown since its launch in 1999. When the euro formally replaced 12 currencies on 1 January 2002, it inherited their use in territories such as Montenegro and replaced minor currencies tied to pre-euro currencies, such as in Monaco. Four small states have been given a formal right to use the euro, and to mint their own coins, but all other usage outside the eurozone has been unofficial. With or without an agreement, these countries, unlike those in the eurozone, do not participate in the European Central Bank or the Eurogroup.
The economic and monetary union (EMU) of the European Union is a group of policies aimed at converging the economies of member states of the European Union at three stages.
Bulgaria 
Czech Republic 
Denmark 
Hungary 
Poland 
Romania 
Sweden 
Campione d'Italia (part of Italy) [lower-alpha 1] 
Büsingen am Hochrhein (part of Germany) [lower-alpha 2] 
Northern Cyprus (de jure part of Cyprus) [lower-alpha 3] 
