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.
The Anglo-Irish Treaty was narrowly ratified by the Dáil in December 1921 but was rejected a large minority, resulting in the Irish Civil War which lasted until 1923. In 1922, in the middle of this war, the Irish Free State came into being. For its first years the new state was governed by the victors of the Civil War. However in the 1930s Fianna Fáil, the party of the opponents of the treaty, were elected into government. The party introduced a new constitution in 1937 which renamed the state to simply "Ireland".
A number of political parties are represented in the Dáil and coalition governments are common. Neither of the two largest parties, Fianna Fáil and Fine Gael, strongly identifies itself as either a left or right-wing group. The third largest party in the state is the centre-left Labour Party. Labour is joined on the left by the Green Party, Sinn Féin and the Socialist Party. The right is represented by the Progressive Democrats who, while liberal on economic policy, are left-wing on social matters. Independent TDs (MPs) also play an important role in Irish politics.
The Constitution of Ireland guarantees the rights of the family and the institution of marriage. However, the reality is that social and economic change in recent years has brought about significant changes in family life in the Republic. According to figures published in September, 2004, 31% of all births in the Republic of Ireland occur outside marriage. This compares with 5% in 1980. The average of mothers having their first child was 30 and the fertility is an average of 1.98 children.
There have been recent efforts in Ireland to use renewable energy such as wind energy with large wind farms being constructed in coastal counties such as Mayo and County Antrim. Recently what will be the world's largest offshore wind farm is being developed at Arklow Bank off the coast of Wicklow. It is estimated to generate 10% of Irelands energy needs when it is complete. These constructions have in some cases been delayed by opposition from locals, most recently on Achill Island, some of whom consider the wind turbines to be unsightly. Another issue in the Republic of Ireland is the failure of the aging network to cope with the varying availability of power from such installations. Turlough Hill is the only energy storage mechanism in Ireland.
A majority of the present-day population are unionist and wish to remain part of the United Kingdom, but a significant minority, known as nationalists, want to see a united Ireland. These two views are linked to deeper cultural divisions. Unionists are predominantly Protestant and often descendants of Scottish and English (mainly Scottish) settlement in previous centuries, while nationalists are predominantly Catholic and usually descend from the Irish population predating such settlement. The conflict between these two sets of identities, including alleged discrimination against nationalists under the Stormont government (1920–72) giving rise to the nationalist "Civil Rights Movement" in the 1960s, and eventually to a long-running conflict known as The Troubles.
The island is often referred to as being part of the British Isles. However, some people, especially in Ireland, take exception to this name, which seems to suggest that both islands belong to Britain. 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).
Much of the Irish calendar still today reflects the old pagan customs, with later Christian traditions also having significant influence. As in other countries, the date for observing Christmas was deliberately chosen to coincide with the winter solstice. Christmas in Ireland has several local traditions, some in no way connected with Christianity. On 6 January, which is known as "The Little Christmas" (An Nollaig Bhéag) or "The Women's Christmas" (Nollaig na mBan), there is a custom of "Wren boys" who call door to door, in times past, with a dead wren.