structural:summarization, structural:reformatting, stylistic:style_transfer
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. There are three stages of the EMU, each of which consists of progressively closer economic integration. Only once a state participates in the third stage it is permitted to adopt the euro as its official currency. As such, the third stage is largely synonymous with the eurozone. The euro convergence criteria are the set of requirements that needs to be fulfilled in order for a country to be approved to participate in the third stage. An important element of this is participation for a minimum of two years in the European Exchange Rate Mechanism ("ERM II"), in which candidate currencies demonstrate economic convergence by maintaining limited deviation from their target rate against the euro. The EMU policies cover all European Union member states. All new EU member states must commit to participate in the third stage in their treaties of accession and are obliged to enter the third stage once they comply with all convergence criteria. Twenty EU member states, including most recently Croatia, have entered the third stage and have adopted the euro as their currency. Denmark, whose EU membership predates the introduction of the euro, has a legal opt-out from the EU Treaties and is thus not required to enter the third stage.