A candidate country that meets the accession criteria as defined by the Copenhagen European Council of 1993 and signs the accession Treaty with the individual EU countries becomes a Member State of the European Union.
Since 1 July 2013, when Croatia joined the EU, the European Union counts 28 Member States which are:
Belgium, Bulgaria, Czech Republic, Denmark, Germany, Estonia, Ireland, Greece, Spain, France, Croatia, Italy, Cyprus, Latvia, Lithuania, Luxembourg, Hungary, Malta, the Netherlands, Austria, Poland, Portugal, Romania, Slovenia, Slovakia, Finland, Sweden and the United Kingdom.
In the summaries of EU legislation, the term ´EU countries` is increasingly used instead of ‘Member States’ (the term which is used in legal acts and documents), in order to make the summaries more understandable.
Source: EUR Lex Glossary