Various words and phrases have been used to describe the overlapping geographical and political areas of the islands of Great Britain, Ireland, and the smaller surrounding islands, together known as the British Isles. The terms are often a source of confusion, partly owing to the similarity between some of the actual words used but also because they are often used loosely.

Many of the words carry geographical and political connotations effected by the history of the islands. The inclusion of Ireland in the geographical definition of British Isles is debated: for example, Ordnance Survey Ireland does not use the term.

Summary The use of terms depends on context; words and phrases can be grouped into geographical, political, linguistic and sporting terms. In brief, the main terms and their simple explanations are as follows: Geographical terms: The British Isles is an archipelago in the Atlantic Ocean off the coast of Continental Europe. It includes Ireland, Great Britain, the Isle of Man, Shetland, Orkney and thousands of smaller islands. Traditionally the Channel Islands are included, though they are geographically closer to mainland continental Europe, off the French coast of Normandy. This, in part, has resulted in the term being disputed.; "Written Answers – Official Terms" , Dáil Éireann, Volume 606, 28 September 2005. In his response, the Irish Minister for Foreign Affairs stated that "The British Isles is not an officially recognised term in any legal or inter-governmental sense. It is without any official status. The Government, including the Department of Foreign Affairs, does not use this term. Our officials in the Embassy of Ireland, London, continue to monitor the media in Britain for any abuse of the official terms as set out in the Constitution of Ireland and legislation. These include the name of the State, the President, Taoiseach and others." Great Britain is the largest island of the archipelago."Britain", Oxford English Dictionary: "More fully Great Britain. The term Great Britain includes England, Scotland and Wales; it does not include Northern Ireland. As a geographical and political term: (the main island and smaller offshore islands making up) England, Scotland, and Wales, sometimes with the Isle of Man"; New Oxford American Dictionary: "Britain: an island that consists of England, Wales, and Scotland. The name is broadly synonymous with Great Britain, but the longer form is more usual for the political unit."; "Britain", Oxford English Dictionary (Online Edition): "Britain: 1a – The proper name of the whole island containing England, Wales, and Scotland, with their dependencies; more fully called Great Britain; now also used for the British state or empire as a whole." Ireland is the second-largest island of the archipelago and lies directly to the west of Great Britain. The island of Ireland itself has its own offshore islands. The full list of islands of the British Isles includes over 6,000 islands, of which 51 have an area larger than .There are no official definitions, but Scotland has over 790 offshore islands plus numerous freshwater islands so a complete list of the British Isles would probably have between 1,000 and 2,000 entries. Political terms: The United Kingdom of Great Britain and Northern Ireland is the parliamentary constitutional monarchy occupying the island of Great Britain, the small nearby islands (but not the Isle of Man or the Channel Islands), and the north-eastern part of the island of Ireland. Usually, it is shortened to the United Kingdom or the UK, or Britain. Great Britain is sometimes used as a short form and is the name used by the UK in some international organisations. The abbreviation GB is frequently used for the United Kingdom of Great Britain and Northern Ireland in international agreements, e.g. Universal Postal Union and Road Traffic Convention, as well as in the ISO 3166 country codes (GB and GBR). England was also formerly used synecdochically to refer to the whole United Kingdom but this usage became rare early in the 20th century (though it persists in other languages). Ireland is the sovereign republic occupying the larger portion of the island of Ireland. To distinguish the state from the island, or to distinguish either of these from Northern Ireland, it is also called "the Republic of Ireland" or simply "the Republic". In the past, its Irish-language name, Éire (or Eire without the diacritic), was often used in an English-language context to distinguish it from Northern Ireland and from the island of Ireland. England, Scotland, Wales and Northern Ireland are the four countries of the United Kingdom, though they are also referred to, especially in sporting contexts, as the home nations of the United Kingdom. England and Wales, Scotland, and Northern Ireland are separate legal jurisdictions within the United Kingdom.Though the statute law applicable in Wales has diverged further from that applicable in England since devolution from the UK government to the National Assembly for Wales, "England and Wales" remains a single jurisdiction. Great Britain means the countries of England, Wales and Scotland, considered as a unit."Great Britain", New Oxford American Dictionary: "Great Britain: England, Wales, and Scotland considered as a unit. The name is also often used loosely to refer to the United Kingdom."; The British Islands consist of the United Kingdom, the Channel Islands and the Isle of Man. These are the polities in and near the British Isles that have the British monarch as head of state. Some organisations, such as Royal Mail, can use "UK" to describe this grouping. Linguistic terms: The two sovereign states in the region, the United Kingdom and Ireland, are frequently referred to as countries. So too are England, Wales, Scotland and, to a lesser extent, Northern Ireland (as is the whole island of Ireland). British is an adjective of the United Kingdom; for example, a citizen of the UK is called a British citizen—but for citizenship purposes "British" includes the Channel Islands and the Isle of Man. "Anglo-" is often used as an adjectival prefix referring to the United Kingdom (notwithstanding that its original meaning is "English"), particularly in the field of diplomatic relations. It can also refer to the English language or to anglophone peoples, and can have a variety of other shades of meaning. Wales is sometimes called the Principality of Wales, although this has no modern constitutional basis. Northern Ireland is often referred to as a province or called Ulster, after the traditional Irish province of Ulster within which it is located. Sports: Forms of national representation vary from sport to sport. England, Scotland and Wales often compete separately as nations. In some sports—such as rugby and cricket—the island of Ireland competes as a nation; in others, most notably association football, Northern Ireland and the Republic of Ireland field separate teams. In these contexts England, Scotland, Wales and Ireland/Northern Ireland are sometimes described as the home nations. Forms of representation can also vary within a sport. In women's association football, for instance, England, Scotland, Wales, and Northern Ireland compete as separate nations at the FIFA Women's World Cup but join together as the Great Britain Olympic football team ("Team GB") for the Olympics. Rugby union players from both Ireland and Great Britain play for the British and Irish Lions representing the four "Home Unions" of England, Ireland, Scotland and Wales. "Great Britain" is sometimes used to mean "United Kingdom". For example, at the Olympic Games, the team called "Great Britain" marches under the letter "G" in the Parade of Nations and represents Great Britain and Northern Ireland."Team GB". British Olympic Association. . Retrieved 2 January 2011."Irish and GB in Olympic row". BBC Sport. 27 January 2004. Retrieved 1 January 2011. However, athletes from Northern Ireland have the choice of participating in either the Great Britain team or the Republic of Ireland team. Conversely, at the Universiade, the team marches under the full name "United Kingdom of Great Britain and Northern Ireland" under the letter "U" in the Parade of Nations. In the majority of individual sports (e.g. tennis and athletics), at the international level competitors are identified as GB if they are from Great Britain or Northern Ireland. A small number of sports (e.g. golf, darts, snooker) identify participants as representing their constituent country. In the Commonwealth Games, England, Northern Ireland, Scotland and Wales each compete as separate nations, as do each of the three Crown Dependencies (Ireland is not part of the Commonwealth and is not eligible to participate).

Visual guide Below is a visual reference guide to some of the main concepts and territories described in this article:

Terminology in detail Britain is a political and geographic term which can refer to the United Kingdom of Great Britain and Northern Ireland,"the term 'Britain' is used informally to mean the United Kingdom of Great Britain and Northern Ireland". Cabinet Office or the island of Great Britain. Great Britain is the largest island in Europe and the political union of three nations, these being: England and Wales is a political and administrative term referring to the two home countries of England and Wales, which share the same legal system. Between 1746 and 1967 the term "England" did legally include Wales. England (see also the historical Kingdom of England). Wales (see also the historical Principality of Wales). Scotland (see also the historical Kingdom of Scotland) The historical Kingdom of Great Britain is Britain during the period 1707–1801. is the Latin name for Great Britain or for the Roman province of Britain, or a poetic reference to later Britain, or a female personification of Britain. The United Kingdom of Great Britain and Northern Ireland, usually shortened to "the United Kingdom" (abbreviation UK), is the sovereign state comprising Great Britain plus Northern Ireland since 1927. (The Partition of Ireland took place in 1922, but the consequent change in the official title of the UK was only made by Act of Parliament five years later.) The United Kingdom is often called Britain, even on official websites,; where such use is described as "informal". A proposal to rename the political entity as the "United Kingdom of Great Britain and Ulster" was formally recommended by civil servants to the Cabinet in 1949 but ultimately rejected.British Archives, Catalogue Reference:CAB/129/32 (Memorandum by PM Attlee to Cabinet appending Working Party Report); Quoted at length at Alternative names for Northern Ireland. The historical United Kingdom of Great Britain and Ireland was Great Britain plus Ireland, during the period 1801 to 1922, although the name change after the secession of the Irish Free State only took place in 1927. While "United Kingdom" is normally abbreviated UK, the official ISO 3166 two-letter country code is GB and the three letter code is GBR. Due to a pre-existing convention originating in the UK's JANET academic computer network,"Electronic Mail address changes" On the transition from big-endian to little-endian notation (Department of Mechanical Engineering, University of Leeds) the UK's Internet top-level domain is .uk, a break from the TCP/IP practice of following ISO 3166 (a .gb domain has also been used to a limited extent in the past but is now defunct). GB was also used on car number plates to indicate the United Kingdom until September 2021. The car sticker has been 'UK' since then."GB (now UK) car sticker?" Department for Transport Ireland () refers, geographically, to the island of Ireland, or to any of the following:

Historically: