Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia join the European Union, celebrated at the residence of the Irish President in Dublin.

The European Union (EU) is a political and economic union of 27 member states that are located primarily in Europe. The union has a total area of 4,233,255.3 km2 (1,634,469.0 sq mi) and an estimated total population of about 447 million. An internal single market has been established through a standardised system of laws that apply in all member states in those matters, and only those matters, where the states have agreed to act as one. EU policies aim to ensure the free movement of people, goods, services and capital within the internal market; enact legislation in justice and home affairs; and maintain common policies on trade, agriculture, fisheries and regional development. Passport controls have been abolished for travel within the Schengen Area. The eurozone is a monetary union established in 1999, coming into full force in 2002, that is composed of the 19 EU member states that use the euro currency. The EU has often been described as a sui generis political entity (without precedent or comparison) with the characteristics of either a federation or confederation.The union and EU citizenship were established when the Maastricht Treaty came into force in 1993. The EU traces its origins to the European Coal and Steel Community (ECSC) and the European Economic Community (EEC), established, respectively, by the 1951 Treaty of Paris and 1957 Treaty of Rome. The original member states of what came to be known as the European Communities were the Inner Six: Belgium, France, Italy, Luxembourg, the Netherlands, and West Germany. The communities and their successors have grown in size by the accession of 21 new member states and in power by the addition of policy areas to their remit. The latest major amendment to the constitutional basis of the EU, the Treaty of Lisbon, came into force in 2009. In 2020, the United Kingdom became the only member state to leave the EU. Before this, four territories of current member states had left the EU or its forerunners. There are several other countries that are negotiating to join the European Union.

Containing some 5.8 percent of the world population in 2020, the EU had generated a nominal gross domestic product (GDP) of around US$17.1 trillion in 2021, constituting approximately 18 percent of global nominal GDP. Additionally, all EU countries have a very high Human Development Index according to the United Nations Development Programme. In 2012, the EU was awarded the Nobel Peace Prize. Through the Common Foreign and Security Policy, the union has developed a role in external relations and defence. It maintains permanent diplomatic missions throughout the world and represents itself at the United Nations, the World Trade Organization, the G7 and the G20. Due to its global influence, the European Union has been described by some scholars as an emerging superpower.

Cyprus ( (listen)), officially the Republic of Cyprus, is an island country in the eastern Mediterranean Sea south of the Anatolian Peninsula. It is the third-largest and third-most populous island in the Mediterranean, and is located south of Turkey, west of Syria, northwest of Lebanon, Israel, and the Gaza Strip (Palestine), north of Egypt, and southeast of Greece. Its capital and largest city is Nicosia and second largest is Limassol.

The earliest known human activity on the island dates to around the 10th millennium BC. Archaeological remains from this period include the well-preserved Neolithic village of Khirokitia, and Cyprus is home to some of the oldest water wells in the world. Cyprus was settled by Mycenaean Greeks in two waves in the 2nd millennium BC. As a strategic location in the Eastern Mediterranean, it was subsequently occupied by several major powers, including the empires of the Assyrians, Egyptians and Persians, from whom the island was seized in 333 BC by Alexander the Great. Subsequent rule by Ptolemaic Egypt, the Classical and Eastern Roman Empire, Arab caliphates for a short period, the French Lusignan dynasty and the Venetians was followed by over three centuries of Ottoman rule between 1571 and 1878 (de jure until 1914).Cyprus was placed under the UK's administration based on the Cyprus Convention in 1878 and was formally annexed by the UK in 1914. The future of the island became a matter of disagreement between the two prominent ethnic communities, Greek Cypriots, who made up 77% of the population in 1960, and Turkish Cypriots, who made up 18% of the population. From the 19th century onwards, the Greek Cypriot population pursued enosis, union with Greece, which became a Greek national policy in the 1950s. The Turkish Cypriot population initially advocated the continuation of the British rule, then demanded the annexation of the island to Turkey, and in the 1950s, together with Turkey, established a policy of taksim, the partition of Cyprus and the creation of a Turkish polity in the north. Following nationalist violence in the 1950s, Cyprus was granted independence in 1960. The crisis of 1963–64 brought further intercommunal violence between the two communities, displaced more than 25,000 Turkish Cypriots into enclaves: 56–59  and brought the end of Turkish Cypriot representation in the republic. On 15 July 1974, a coup d'état was staged by Greek Cypriot nationalists and elements of the Greek military junta in an attempt at enosis. This action precipitated the Turkish invasion of Cyprus on 20 July, which led to the capture of the present-day territory of Northern Cyprus and the displacement of over 150,000 Greek Cypriots and 50,000 Turkish Cypriots. A separate Turkish Cypriot state in the north was established by unilateral declaration in 1983; the move was widely condemned by the international community, with Turkey alone recognising the new state. These events and the resulting political situation are matters of a continuing dispute.

The Republic of Cyprus has de jure sovereignty over the entire island, including its territorial waters and exclusive economic zone, with the exception of the Sovereign Base Areas of Akrotiri and Dhekelia, which remain under the UK's control according to the London and Zürich Agreements. However, the Republic of Cyprus is de facto partitioned into two main parts: the area under the effective control of the Republic, located in the south and west and comprising about 59% of the island's area, and the north, administered by the self-declared Turkish Republic of Northern Cyprus, covering about 36% of the island's area. Another nearly 4% of the island's area is covered by the UN buffer zone. The international community considers the northern part of the island to be territory of the Republic of Cyprus occupied by Turkish forces. The occupation is viewed as illegal under international law and amounting to illegal occupation of EU territory since Cyprus became a member of the European Union.Cyprus is a major tourist destination in the Mediterranean. With an advanced, high-income economy and a very high Human Development Index, the Republic of Cyprus has been a member of the Commonwealth since 1961 and was a founding member of the Non-Aligned Movement until it joined the European Union on 1 May 2004. On 1 January 2008, the Republic of Cyprus joined the eurozone.