EU enlargement is the process through which European states join the European Union under the Union’s accession rules. After the original six EEC members, membership expanded in several waves between 1973 and 2013, bringing in countries from northern and western Europe, the Mediterranean, and central and eastern Europe. Croatia was the most recent country to accede. The United Kingdom, which had joined in 1973, left the EU in 2020; the number of Member States consequently fell from 28 to 27. Albania, Moldova, Montenegro, North Macedonia, Serbia, Türkiye and Ukraine hold candidate status. That status marks a possible route to membership but does not itself confer accession.
Source: European Central Bank (ECB) (source). This glossary entry is an independently worded adaptation of the cited information.