The United Kingdom (UK) comprises four countries: England, Scotland, and Wales (which collectively make up Great Britain) and Northern Ireland^[1][2] (which is variously described as a country, province or region).^[3][4][5]

Although the UK is a unitary sovereign state, Northern Ireland, Scotland, and Wales have gained a degree of autonomy through the process of devolution. The UK Parliament and British Government deal with all reserved matters for Northern Ireland, Scotland, and Wales, but not in general matters that have been devolved to the Northern Ireland Assembly, Scottish Parliament and National Assembly for Wales. Additionally, devolution in Northern Ireland is conditional on co-operation between the Northern Ireland Executive and the Government of Ireland (see North/South Ministerial Council) and the British Government consults with the Government of Ireland to reach agreement on some non-devolved matters for Northern Ireland (see British–Irish Intergovernmental Conference). England, comprising the majority of the population and area of the United Kingdom,^[6][7] remains fully the responsibility of the UK Parliament centralised in London.

England, Northern Ireland, Scotland, and Wales are not themselves listed in the International Organization for Standardization (ISO) list of countries. However the ISO list of the subdivisions of the UK, compiled by British Standards and the UK's Office for National Statistics, uses "country" to describe England, Scotland, and Wales.^[8] Northern Ireland, in contrast, is described as a "province" in the same lists.^[8] Each has separate national governing bodies for sports and compete separately in many international sporting competitions, including the Commonwealth Games. Northern Ireland also forms joint All-Island sporting bodies with the Republic of Ireland for most sports, including rugby union.^[9]

The Channel Islands and the Isle of Man are dependencies of the Crown and are not part of the UK. Similarly, the British overseas territories, remnants of the British Empire, are not part of the UK.

Historically, from 1801, following the Acts of Union, until 1921 the whole island of Ireland was a country within the UK. Ireland was split into two separate jurisdictions in 1921: Southern Ireland and Northern Ireland. Southern Ireland left the United Kingdom, secured full independence and became the Republic of Ireland in 1919.

1 The UK Parliament makes all English legislation, whilst the London Assembly scrutinises the Mayor of London. 2 The UK Government, the Mayor of London and their Mayoral cabinet, Metro Mayors and combined authorities, and the councils of Cornwall and the Isles of Scilly exercise executive power in England. 3 The former flag of Northern Ireland, the Ulster Banner, is still used in some sport-related contexts.

*Gross value added. Figures for GVA do not include oil and gas revenues generated beyond the UK's territorial waters, in the country's continental shelf region.

Various terms have been used to describe England, Northern Ireland, Scotland and Wales.

The Interpretation Act 1978 provides statutory definitions of the terms "England", "Wales" and the "United Kingdom", but neither that Act nor any other current statute defines "Scotland" or "Northern Ireland". Use of the first three terms in other legislation is interpreted following the definitions in the 1978 Act. The definitions in the 1978 Act are listed below:

In the Scotland Act 1998 there is no delineation of Scotland, with the definition in section 126 simply providing that Scotland includes "so much of the internal waters and territorial sea of the United Kingdom as are adjacent to Scotland".

The Parliamentary Voting System and Constituencies Act 2011 refers to England, Scotland, Wales and Northern Ireland as "parts" of the United Kingdom in the following clause: "Each constituency shall be wholly in one of the four parts of the United Kingdom (England, Wales, Scotland and Northern Ireland)."

The Royal Fine Art Commission's 1847 report on decorating the Palace of Westminster referred to "the nationality of the component parts of the United Kingdom" being represented by their four respective patron saints.^[18]

"Regions": For purposes of NUTS 1 collection of statistical data in a format that is compatible with similar data that is collected elsewhere in the European Union, the United Kingdom has been divided into twelve regions of approximately equal size.^[19] Scotland, Wales and Northern Ireland are regions in their own right while England has been divided into nine regions.

The official term rest of the UK (RUK or rUK) is used in Scotland, for example in export statistics^[20] and in legislating for student funding.^[21]

The alternative term Home Nations is sometimes used in sporting contexts and may include all of the island of Ireland.

According to the British Social Attitudes Survey, there are broadly two interpretations of British identity, with ethnic and civic dimensions:

Of the two perspectives of British identity, the civic definition has become the dominant idea and in this capacity, Britishness is sometimes considered an institutional or overarching state identity.^[23][24] This has been used to explain why first-, second- and third-generation immigrants are more likely to describe themselves as British, rather than English, Northern Irish, Scottish or Welsh, because it is an "institutional, inclusive" identity, that can be acquired through naturalisation and British nationality law; the vast majority of people in the United Kingdom who are from an ethnic minority feel British.^[25] However, this attitude is more common in England than in Scotland or Wales; "white English people perceived themselves as English first and as British second, and most people from ethnic minority backgrounds perceived themselves as British, but none identified as English, a label they associated exclusively with white people". Contrariwise, in Scotland and Wales "there was a much stronger identification with each country than with Britain."^[26]

Studies and surveys have reported that the majority of the Scots and Welsh see themselves as both Scottish/Welsh and British though with some differences in emphasis. The Commission for Racial Equality found that with respect to notions of nationality in Britain, "the most basic, objective and uncontroversial conception of the British people is one that includes the English, the Scots and the Welsh".^[27] However, "English participants tended to think of themselves as indistinguishably English or British, while both Scottish and Welsh participants identified themselves much more readily as Scottish or Welsh than as British".^[27] Some people opted "to combine both identities" as "they felt Scottish or Welsh, but held a British passport and were therefore British", whereas others saw themselves as exclusively Scottish or exclusively Welsh and "felt quite divorced from the British, whom they saw as the English".^[27] Commentators have described this latter phenomenon as "nationalism", a rejection of British identity because some Scots and Welsh interpret it as "cultural imperialism imposed" upon the United Kingdom by "English ruling elites",^[28] or else a response to a historical misappropriation of equating the word "English" with "British",^[29] which has "brought about a desire among Scots, Welsh and Irish to learn more about their heritage and distinguish themselves from the broader British identity".^[30] The propensity for nationalistic feeling varies greatly across the UK, and can rise and fall over time.^[31]

The state-funded Northern Ireland Life and Times Survey,^[32] part of a joint project between the University of Ulster and Queen's University Belfast, has addressed the issue of identity in since it started polling in 1998. It reported that 37% of people identified as British, whilst 29% identified as Irish and 24% identified as Northern Irish. 3% opted to identify themselves as Ulster, whereas 7% stated 'other'. Of the two main religious groups, 68% of Protestants identified as British as did 6% of Catholics; 60% of Catholics identified as Irish as did 3% of Protestants. 21% of Protestants and 26% of Catholics identified as Northern Irish.^[33]

For Northern Ireland, however, the results of the Life & Times Survey are not the whole story. The poll asks for a single preference, whereas many people easily identify as any combination of British and Irish, or British, Northern Irish and Irish, or Irish and Northern Irish. The 2014 Life & Times Survey addressed this to an extent by choosing two of the options from the identity question: British and Irish. It found that, while 28% of respondents stated they felt "British not Irish" and 26% felt "Irish not British", 39% of respondents felt some combination of both identities. Six percent chose 'other description'.^[34]

The identity question is confounded further by identity with politics and religion, and particularly by a stance on the constitutional status of Northern Ireland. Again in 2014, the Life & Times Survey asked what respondents felt should be the "long term future for Northern Ireland". 66% of respondents felt the future should be as a part of the UK, with or without devolved government. 17% felt that Northern Ireland should unify with the Republic of Ireland. 50% of specifically Roman Catholics considered that the long-term future should be as part of the UK, with 32% opting for separation. 87% of respondents identifying as any Protestant denomination opted for remaining part of the UK, with only 4% opting for separation. Of those respondents who declared no religion, 62% opted for remaining part of the UK, with 9% opting for separation.^[34]

Following devolution and the significant broadening of autonomous governance throughout the UK in the late 1990s, debate has taken place across the United Kingdom on the relative value of full independence,^[35] an option that was rejected^[36] by the Scottish people in the 2014 Scottish independence referendum.

Cornwall is administered as a county of England, but the Cornish people are a recognised national minority, included under the terms of the Framework Convention for the Protection of National Minorities in 2014.^[37][38]

Each of England, Northern Ireland, Scotland, and Wales has separate national governing bodies for sports and competes separately in many international sporting competitions.^{[39][40][41][42]} Each country of the United Kingdom has a national football team, and competes as a separate national team in the various disciplines in the Commonwealth Games.^[43] At the Olympic Games, the United Kingdom is represented by the Great Britain and Northern Ireland team, although athletes from Northern Ireland can choose to join the Republic of Ireland's Olympic team.^[43][44] In addition to Northern Ireland having its own national governing bodies for some sports such as Association football and Netball, for others, such as rugby union and cricket, Northern Ireland participates with the Republic of Ireland in a joint All-Ireland team. England and Wales field a joint cricket team.

The United Kingdom participates in the Eurovision Song Contest as a single entity, though there have been calls for separate and Scottish and Welsh entrants. In 2017, Wales participated alone in the spin-off "Choir of the Year".