Prior to the Government of Ireland Act 1920 the island had existed for centuries as one unified political entity, either on its own (as the Lordship of Ireland, the Kingdom of Ireland) or as part of the United Kingdom of Great Britain and Ireland. Prior to English rule in mediæval times the island was made up of a patchwork of small kingdoms that were people and clan rather than territory-based. At the top of this system was the Ard Ri or High King of Ireland. See Irish States (1171-present).
The vast majority of the population of Northern Ireland identifies with one of two different groups, unionists and nationalists. Both sides of the community are often described by their predominant religious attachments. Unionists are predominantly Protestant (the major Protestant faith is Presbyterianism, the second in terms of size is the Church of Ireland), while nationalists are predominantly Catholic. However, contrary to widespread belief, not all Catholics necessarily support nationalism, and not all Protestants necessarily support unionism. It is also important to note that, in parallel with other parts of Europe, the proportion of the population practising their religious beliefs has fallen dramatically in recent decades, particularly among Catholics and adherents of mainstream Protestant denominations. This has not necessarily resulted in a weakening of communal feeling.
Under the Belfast Agreement (also known as the Good Friday Agreement) and Article 3 of the constitution a North-South Ministerial Council and six North-South Implementation Bodies coordinate activities and exercise a limited governmental role within certain policy areas across the whole island of Ireland. The Implementation Bodies have limited executive authority in six policy areas. Meetings of the Council take the form of meetings between ministers from both the Republic's Government and the Northern Ireland Executive.
The three most important international airports in the Republic are Dublin Airport, Cork Airport and Shannon Airport. All provide extensive services to the UK, Europe and North America. The Irish national airline Aer Lingus and low-cost operator Ryanair are based at Dublin. Shannon is an important stopover on trans-Atlantic route for refuelling operations. There are several smaller regional airports in the Republic (Galway Airport, Kerry Airport, Knock Airport, Sligo Airport, Waterford Airport) that mostly limit their services to Ireland and the United Kingdom.
The head of state is the President of Ireland. In keeping with the state's parliamentary system of government the President exercises largely a ceremonial role but does possess certain reserve powers. The presidency is open to all citizens who are at least 35. They are directly elected by secret ballot under the Alternative Vote. A candidate may also be chosen by a consensus among the political parties, in which case it is unnecessary to proceed to a ballot. The President is elected to a seven year term; no candidate may serve more than two terms. In carrying out certain of her constitutional functions, the President is aided by the Council of State.
Political parties in Northern Ireland can be divided into three distinct categories: unionist parties, such as the Democratic Unionist Party, the Ulster Unionist Party, and other smaller parties such as the Progressive Unionist Party and the United Kingdom Unionist Party; nationalist parties, Sinn Féin and the Social Democratic and Labour Party (SDLP); and cross-community parties such as the Alliance Party and the Northern Ireland Women's Coalition.
In a number of areas, the island operates officially as a single entity, for example, in sport. The major religions, the Roman Catholic Church, the Church of Ireland and the Presbyterian Church of Ireland, are organised on an all-island basis. 92% of the population of the Republic of Ireland are Roman Catholic, and 40% in Northern Ireland. Some trades unions are also organised 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. The island also has a shared culture across the divide 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 are similar.
