Member state of the European Union

The Progressive Alliance of Socialists and Democrats (S&D) is the political group in the European Parliament of the Party of European Socialists (PES). The Progressive Alliance of Socialists and Democrats was officially founded as a Socialist Group on 29 June 1953, which makes it the second oldest political group in the European Parliament after the European People's Party Group (EPP Group). It adopted its present-day name on 23 June 2009. Centre-left in orientation, the group mostly comprises social democratic parties and is affiliated with the Progressive Alliance and Socialist International.

Until the 1999 European Parliament elections, it was the largest group in the Parliament, but since then it has always been the second-largest group. During the eighth EU Parliament Assembly, the S&D was the only Parliament group with representation from all 27 EU member states. In the current EU Parliament the S&D is currently composed of 136 members from 25 member states.

A Member of the European Parliament (MEP) is a person who has been elected to serve as a popular representative in the European Parliament.

When the European Parliament (then known as the Common Assembly of the European Coal and Steel Community) first met in 1952, its members were directly appointed by the governments of member states from among those already sitting in their own national parliaments. Since 1979, however, MEPs have been elected by direct universal suffrage every five years. Each member state establishes its own method for electing MEPs – and in some states this has changed over time – but the system chosen must be a form of proportional representation. Some member states elect their MEPs to represent a single national constituency; other states apportion seats to sub-national regions for election.

The 1979 European Parliament election was a series of parliamentary elections held across all 9 (at the time) European Community member states. They were the first European elections to be held, allowing citizens to elect 410 MEPs to the European Parliament, and also the first international election in history.

Seats in the Parliament had been allocated to the states according to population, and in some cases were divided into constituencies, but members sat according to political groups.

The president of the European Parliament presides over the debates and activities of the European Parliament. They also represent the Parliament within the European Union (EU) and internationally. The president's signature is required for laws initiated under co-decision and the EU budget.

Presidents serve 2.5-year terms, normally alternating between the two major political parties. There have been 30 presidents since the Parliament was created in 1952, 17 of whom have served since the first parliamentary election in 1979. Three presidents have been women and most have come from the older member states.

The euro (symbol: €; currency code: EUR) is the official currency of 20 of the 27 member states of the European Union. This group of states is officially known as the euro area or, more commonly, the eurozone. The euro is divided into 100 euro cents.

The currency is also used officially by the institutions of the European Union, by four European microstates that are not EU members, and the British Overseas Territory of Akrotiri and Dhekelia, as well as unilaterally by Montenegro and Kosovo. Outside Europe, a number of special territories of EU members also use the euro as their currency.

The primacy of European Union law (sometimes referred to as supremacy or precedence of European law) is a legal principle of rule according to higher law establishing precedence of European Union law over conflicting national laws of EU member states.

The principle was derived from an interpretation of the European Court of Justice, which ruled that European law has priority over any contravening national law, including the constitution of a member state itself. For the European Court of Justice, national courts and public officials must disapply a national norm that they consider not to be compliant with the EU law.

The European Economic Area (EEA) has 32 special territories of EU member states and EFTA member states which, for historical, geographical, or political reasons, enjoy special status within or outside the European Union and the European Free Trade Association.

The special territories of EU member states are categorised under three headings: nine Outermost Regions (OMR) that form part of the European Union, though they benefit from derogations from some EU laws due to their geographical remoteness from mainland Europe; thirteen Overseas Countries and Territories (OCT) that do not form part of the European Union, though they cooperate with the EU via the Overseas Countries and Territories Association; and ten special cases that form part of the European Union (with the exception of the Faroe Islands), though EU laws make ad hoc provisions. The Outermost Regions were recognised at the signing of the Maastricht Treaty in 1992, and confirmed by the Treaty of Lisbon in 2007.

The euro area, commonly called the eurozone (EZ), is a currency union of 20 member states of the European Union (EU) that have adopted the euro (€) as their primary currency and sole legal tender, and have thus fully implemented Economic and Monetary Union policies.

The 20 eurozone members are:Austria, Belgium, Croatia, Cyprus, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Portugal, Slovakia, Slovenia, and Spain.

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.