European Union–Turkey Customs Union in the context of "European Single Market"

The European single market, also known as the European internal market or the European common market, is the single market comprising mainly the 27 member states of the European Union (EU). With certain exceptions, it also comprises Iceland, Liechtenstein, Norway (through the Agreement on the European Economic Area), and Switzerland (through sectoral treaties). The single market seeks to guarantee the free movement of goods, capital, services, and people, known collectively as the four freedoms of the European Union. This is achieved through common rules and standards that all participating states are legally committed to follow.

Any potential EU accession candidates are required to make association agreements with the EU during the negotiation, which must be implemented prior to accession. In addition, through three individual agreements on a Deep and Comprehensive Free Trade Area (DCFTA) with the EU, Georgia, Moldova, and Ukraine have also been granted limited access to the single market in selected sectors. Turkey has access to the free movement of some goods via its membership in the European Union–Turkey Customs Union. The United Kingdom left the European single market on 31 December 2020. An agreement was reached between the UK Government and European Commission to align Northern Ireland on rules for goods with the European single market, to maintain an open border on the island of Ireland.