The European Union (EU) is a political and economic union of 27 member states that are party to the EU's founding treaties, and thereby subject to the privileges and obligations of membership. They have agreed by the treaties to … 展开

Abbreviations have been used as a shorthand way of grouping countries by their date of accession.
• EU15 includes the fifteen countries in the European Union from 1 … 展开

Each state has representation in the institutions of the European Union. Full membership gives the government of a member state a seat in the Council of the European Union and European Council. When decisions are not being taken by consensus, 展开

EU integration is not always symmetrical, with some states proceeding with integration ahead of hold-outs. There are several different forms of closer integration both within and outside the EU's normal framework. One mechanism is enhanced cooperation 展开

Notes
1. ^ De facto (though not de jure) excludes the disputed territory of Turkish Cyprus and the U.N. buffer zone. See: Cyprus dispute. 展开

Enlargement
According to the Copenhagen criteria, membership of the European Union is open to any European … 展开

While the member states are sovereign, the union partially follows a supranational system for those functions agreed by treaty to be shared. ("Competences not conferred upon the Union in the Treaties remain with the member states"). Previously limited to 展开