EU enlargement: the Copenhagen criteria and the three steps to accession

Background

Enlargement happens when new countries join the European Union, and it has taken place several times in the Union's history.
Any European country can join the EU if it fulfils the membership criteria, also known as the Copenhagen criteria.
The criteria require stable institutions that can guarantee democracy, the rule of law, human rights and the protection of minorities.
They require a functioning market economy and the ability to cope with the competitive pressure of the EU market.
They also require the ability to take on the obligations of EU membership, including the capacity to implement all EU law.
The accession process has three main steps: Candidacy, Membership negotiations and Accession.
A country wishing to join submits a membership application to the Council of the EU, which asks the European Commission to check whether the applicant can fulfil the criteria; all EU Member States must agree before candidate status is granted.
During membership negotiations the candidate prepares to implement EU laws and standards, known as the acquis, and the accession treaty must be approved by the European Commission, the European Council and the European Parliament before being signed and ratified by all EU Member States and the candidate country.