Ireland (Irish: Éire), also known as the Republic of Ireland (Irish: Poblacht na hÉireann), is a sovereign state in Western Europe occupying about five-sixths of the island of Ireland. It is a unitary parliamentary republic. The capital is Dublin in the east of the island. The state shares its only land border with Northern Ireland, a part of the United Kingdom. It is otherwise surrounded by the Atlantic Ocean, with the Celtic Sea to the south, Saint George's Channel to the south east, and the Irish Sea to the east.
The modern Irish state gained independence from the United Kingdom in 1922 following a war of independence resulting in the Anglo-Irish Treaty, with Northern Ireland exercising an option to remain in the United Kingdom. Initially a dominion within the British Empire called the Irish Free State, a new constitution and the name of "Ireland" were adopted in 1937.
Ireland remained neutral during World War II, a period it described as The Emergency. The link with the monarchy ceased with the passage of the Republic of Ireland Act 1948, which came into force on 18 April 1949 and declared that the state was a republic. Ireland joined the United Nations in December 1955, after the lengthy veto both by the United Kingdom and the Soviet Union.