Politically, Ireland is divided into:
The Republic of Ireland, with its capital Dublin. This state is often simply referred to internally and internationally as "Ireland" in English or "ȩre" in Irish. Technically Ireland and ȩre are the official names of the state while the "Republic of Ireland" is its official description.
Northern Ireland is unofficially known as "The North" (by nationalists and residents in the Republic of Ireland), the Six Counties (by nationalists) and "Ulster" (by unionists) (Ulster also includes Donegal, Cavan, and Monaghan, which are in the Republic). Northern Ireland remains a state within the United Kingdom.
Prior to the Government of Ireland Act 1920 the island had been a unified political entity within the United Kingdom of Great Britain and Ireland, from 1801 until 1922. From 1541 the Kingdom of Ireland was established by the King of England, though this realm did not cover the whole island till the early 17th century. Up to then, Ireland had been politically divided into a number of different Irish kingdoms (Leinster, Munster, Connacht, Mide, Ulster, and others).
In a number of respects the island operates officially as a single entity, for example, in most kinds of sports. The major religions, the Roman Catholic Church, the Church of Ireland and the Presbyterian Church in Ireland, are organized on an all-island basis. 88% of the population of the Republic of Ireland (2002 census) and about 44% of Northern Ireland are Roman Catholic. Some trade unions are also organized on an all-Irish basis and associated with the Irish Congress of Trades Unions (ICTU) in Dublin, while others in Northern Ireland are affiliated with the Trades Union Congress (TUC) in the United Kingdom though such unions may organize in both parts of the island as well as in Britain. The island also has a shared culture in many other ways. Traditional Irish music, for example, though showing some variance in all geographical areas, is, broadly speaking, the same on both sides of the border. Irish and Scottish traditional music have many similarities. The Ireland Funds, an international fund-raising organization, tries to help people on both sides find peace and reconciliation through community development, education, arts and culture.
The island is sometimes referred to as being part of the British Isles. However, exception is generally taken by Irish people to this contextualization, which seems to suggest that both islands belong to the United Kingdom. For this reason, "Britain and Ireland" is commonly used as a more neutral alternative. Another suggestion, although much less used, is the Islands of the North Atlantic (IONA).