The United Kingdom is a constitutional monarchy and parliamentary democracy

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, and many smaller islands within the British Isles. Northern Ireland shares a land border with the Republic of Ireland; otherwise, the United Kingdom is surrounded by the Atlantic Ocean, the North Sea, the English Channel, the Celtic Sea and the Irish Sea. The total area of the United Kingdom is 242,495 square kilometres (93,628 sq mi), with an estimated 2020 population of more than 67 million people.
The United Kingdom has evolved from a series of annexations, unions and separations of constituent countries over several hundred years. The Treaty of Union between the Kingdom of England (which included Wales, annexed in 1542) and the Kingdom of Scotland in 1707 formed the Kingdom of Great Britain. Its union in 1801 with the Kingdom of Ireland created the United Kingdom of Great Britain and Ireland. Most of Ireland seceded from the UK in 1922, leaving the present United Kingdom of Great Britain and Northern Ireland, which formally adopted that name in 1927. The nearby Isle of Man, Guernsey and Jersey are not part of the UK, being Crown Dependencies with the British Government responsible for defence and international representation. There are also 14 British Overseas Territories,[20] the last remnants of the British Empire which, at its height in the 1920s, encompassed almost a quarter of the world's landmass and a third of the world's population, and was the largest empire in history. British influence can be observed in the language, culture and the legal and political systems of many of its former colonies.
The United Kingdom is a constitutional monarchy and parliamentary democracy.
The capital and largest city is London, a global city and financial centre with a metropolitan area population of over 14 million. Other major cities include Birmingham, Manchester, Glasgow, Liverpool and Leeds. Scotland, Wales, and Northern Ireland have their own devolved governments, each with varying powers. The UK became the world's first industrialised country and was the world's foremost power during the 19th and early 20th centuries, during a period of unchallenged global hegemony known as "Pax Britannica". In the 21st century, the UK remains a great power and has significant economic, cultural, military, scientific, technological and political influence internationally. The United Kingdom has the world's sixth-largest economy by nominal gross domestic product (GDP), and the eighth-largest by purchasing power parity. It has a high-income economy and a very high Human Development Index rating, ranking 18th in the world. It also performs well in international rankings of education, healthcare, life expectancy and human development.[36] It is a recognised nuclear state and is ranked fourth globally in military expenditure. It has been a permanent member of the United Nations Security Council since its first session in 1946.
The United Kingdom is a member of the Commonwealth of Nations, the Council of Europe, the G7, the Group of Ten, the G20, Five Eyes, the United Nations, NATO, AUKUS, the Organisation for Economic Co-operation and Development (OECD), Interpol, and the World Trade Organization (WTO). The UK is also considered a part of the "Big Four", or G4, an unofficial grouping of important European nations. It was a member state of the European Communities (EC) and its successor, the European Union (EU), from its accession in 1973 until its withdrawal in 2020 following a referendum held in 2016.
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,[k][14] is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland.[16] The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, and many smaller islands within the British Isles. Northern Ireland shares a land border with the Republic of Ireland; otherwise, the United Kingdom is surrounded by the Atlantic Ocean, the North Sea, the English Channel, the Celtic Sea and the Irish Sea. The total area of the United Kingdom is 242,495 square kilometres (93,628 sq mi), with an estimated 2020 population of more than 67 million people.
The United Kingdom has evolved from a series of annexations, unions and separations of constituent countries over several hundred years. The Treaty of Union between the Kingdom of England (which included Wales, annexed in 1542) and the Kingdom of Scotland in 1707 formed the Kingdom of Great Britain. Its union in 1801 with the Kingdom of Ireland created the United Kingdom of Great Britain and Ireland. Most of Ireland seceded from the UK in 1922, leaving the present United Kingdom of Great Britain and Northern Ireland, which formally adopted that name in 1927.The nearby Isle of Man, Guernsey and Jersey are not part of the UK, being Crown Dependencies with the British Government responsible for defence and international representation.There are also 14 British Overseas Territories,]the last remnants of the British Empire which, at its height in the 1920s, encompassed almost a quarter of the world's landmass and a third of the world's population, and was the largest empire in history. British influence can be observed in the language, culture and the legal and political systems of many of its former colonies.[21][22]
The United Kingdom is a constitutional monarchy and parliamentary democracy.[m][24] The capital and largest city is London, a global city and financial centre with a metropolitan area population of over 14 million. Other major cities include Birmingham, Manchester, Glasgow, Liverpool and Leeds. Scotland, Wales, and Northern Ireland have their own devolved governments, each with varying powers. The UK became the world's first industrialised country and was the world's foremost power during the 19th and early 20th centuries, during a period of unchallenged global hegemony known as "Pax Britannica". In the 21st century, the UK remains a great power and has significant economic, cultural, military, scientific, technological and political influence internationally The United Kingdom has the world's sixth-largest economy by nominal gross domestic product (GDP), and the eighth-largest by purchasing power parity. It has a high-income economy and a very high Human Development Index rating, ranking 18th in the world. It also performs well in international rankings of education, healthcare, life expectancy and human development. It is a recognised nuclear state and is ranked fourth globally in military expenditure. It has been a permanent member of the United Nations Security Council since its first session in 1946.
The United Kingdom is a member of the Commonwealth of Nations, the Council of Europe, the G7, the Group of Ten, the G20, Five Eyes, the United Nations, NATO, AUKUS, the Organisation for Economic Co-operation and Development (OECD), Interpol, and the World Trade Organization (WTO). The UK is also considered a part of the "Big Four", or G4, an unofficial grouping of important European nations. It was a member state of the European Communities (EC) and its successor, the European Union (EU), from its accession in 1973 until its withdrawal in 2020 following a referendum held in 2016.

The total area of the United Kingdom is approximately 244,820 square kilometres (94,530 sq mi). The country occupies the major part of the British Isles[137] archipelago and includes the island of Great Britain, the north-eastern one-sixth of the island of Ireland and some smaller surrounding islands. It lies between the North Atlantic Ocean and the North Sea with the southeast coast coming within 22 miles (35 km) of the coast of northern France, from which it is separated by the English Channel.[138]

In 1993 10 per cent of the UK was forested, 46 per cent used for pastures and 25 per cent cultivated for agriculture.[139] The Royal Greenwich Observatory in London was chosen as the defining point of the Prime Meridian[140] in Washington, DC, in 1884, although due to more accurate modern measurement the meridian actually lies 100 metres to the east of the observatory.[141]
The United Kingdom lies between latitudes 49° and 61° N, and longitudes 9° W and 2° E. Northern Ireland shares a 224-mile (360 km) land boundary with the Republic of Ireland.[138] The coastline of Great Britain is 11,073 miles (17,820 km) long.[142] It is connected to continental Europe by the Channel Tunnel, which at 31 miles (50 km) (24 miles (38 km) underwater) is the longest underwater tunnel in the world.[143]
The UK contains four terrestrial ecoregions: Celtic broadleaf forests, English Lowlands beech forests, North Atlantic moist mixed forests, and Caledon conifer forests.[144] The country had a 2019 Forest Landscape Integrity Index mean score of 1.65/10, ranking it 161th globally out of 172 countries.[145]
Climate
Main article: Climate of the United Kingdom
Most of the United Kingdom has a temperate climate, with generally cool temperatures and plentiful rainfall all year round.[138] The temperature varies with the seasons seldom dropping below 0 °C (32 °F) or rising above 30 °C (86 °F).[146] Some parts, away from the coast, of upland England, Wales, Northern Ireland and most of Scotland, experience a subpolar oceanic climate (Cfc). Higher elevations in Scotland experience a continental subarctic climate (Dfc) and the mountains experience a tundra climate (ET).[147]
The prevailing wind is from the southwest and bears frequent spells of mild and wet weather from the Atlantic Ocean,[138] although the eastern parts are mostly sheltered from this wind since the majority of the rain falls over the western regions the eastern parts are therefore the driest. Atlantic currents, warmed by the Gulf Stream, bring mild winters; especially in the west where winters are wet and even more so over high ground. Summers are warmest in the southeast of England and coolest in the north. Heavy snowfall can occur in winter and early spring on high ground, and occasionally settles to great depth away from the hills.[148]
The average total annual sunshine in the United Kingdom is 1339.7 hours, which is just under 30% of the maximum possible (The maximum hours of sunshine possible in one year is approximately 4476 hours).[149] The hours of sunshine vary from 1200 to about 1580 hours per year, and since 1996 the UK has been and still is receiving above the 1981 to 2010 average hours of sunshine[150]
United Kingdom is ranked 4 out of 180 countries in the Environmental Performance Index.[151] A law has been passed that UK greenhouse gas emissions will be net zero by 2050.[152]

Devolved governments

Main articles: Devolution in the United Kingdom, List of leaders of devolved administrations, Northern Ireland Executive, Scottish Government, and Welsh Government

Scotland, Wales and Northern Ireland each have their own government or executive, led by a first minister (or, in the case of Northern Ireland, a diarchal first minister and deputy first minister), and a devolved unicameral legislature. England, the largest country of the United Kingdom, has no devolved executive or legislature and is administered and legislated for directly by the UK's government and parliament on all issues. This situation has given rise to the so-called West Lothian question, which concerns the fact that members of parliament from Scotland, Wales and Northern Ireland can vote, sometimes decisively,[196] on matters that affect only England.[197] The 2013 McKay Commission on this recommended that laws affecting only England should need support from a majority of English members of parliament.

The UK has a partially regulated market economy.[258] Based on market exchange rates, the UK is today the fifth-largest economy in the world and the second-largest in Europe after Germany. HM Treasury, led by the Chancellor of the Exchequer, is responsible for developing and executing the government's public finance policy and economic policy. The Bank of England is the UK's central bank and is responsible for issuing notes and coins in the nation's currency, the pound sterling. Banks in Scotland and Northern Ireland retain the right to issue their own notes, subject to retaining enough Bank of England notes in reserve to cover their issue. The pound sterling is the world's fourth-largest reserve currency (after the US dollar, euro, and Japanese Yen).[259] Since 1997 the Bank of England's Monetary Policy Committee, headed by the Governor of the Bank of England, has been responsible for setting interest rates at the level necessary to achieve the overall inflation target for the economy that is set by the Chancellor each year.[260]
The UK service sector makes up around 79 per cent of GDP.[261] London is one of the world's largest financial centres, ranking second in the world, behind New York City, in the Global Financial Centres Index in 2020.[262] London also has the largest city GDP in Europe.[263] Edinburgh ranks 17th in the world, and sixth in Western Europe in the Global Financial Centres Index in 2020.[262] Tourism is very important to the British economy; with over 27 million tourists arriving in 2004, the United Kingdom is ranked as the sixth major tourist destination in the world and London has the most international visitors of any city in the world.[264] The creative industries accounted for 7 per cent GVA in 2005 and grew at an average of 6 per cent per annum between 1997 and 2005.[265]

Constitutional principles

Main articles: Government of the United Kingdom and Politics of the United Kingdom
The Constitution of the United Kingdom is uncodified and consists mostly of a collection of disparate written sources, including statutes, judge-made case law and international treaties, together with constitutional conventions.[161] Nevertheless, the Supreme Court recognises a number of principles underlying the British constitution, such as parliamentary sovereignty, the rule of law, democracy, and upholding international law.[162]
The Supreme Court also recognises that some acts of Parliament have special constitutional status, and are therefore part of the constitution.[163] These include Magna Carta, which in 1215 required the King to call a "common counsel" (now called Parliament) to represent people, to hold courts in a fixed place, to guarantee fair trials, to guarantee free movement of people, to free the church from the state, and to guarantee rights of "common" people to use the land.[164] (Most of Magna Carta is no longer in force; those principles it established that still exist are mostly protected by other enactments.) After the Wars of the Three Kingdoms and the Glorious Revolution, the Bill of Rights 1689 and the Claim of Right Act 1689 cemented Parliament's position as the supreme law-making body, and said that the "election of members of Parliament ought to be free".
In accordance with the principle of parliamentary sovereignty, the UK Parliament can carry out constitutional reform through acts of Parliament, and thus has the political power to change or abolish almost any written or unwritten element of the constitution. No sitting parliament can pass laws that future parliaments cannot change.[165]
Parliament
he UK is a parliamentary democracy operating under the Westminster system, otherwise known as a "democratic parliamentary monarchy".[167] The Parliament of the United Kingdom is sovereign.[168] It is made up of the House of Commons, the House of Lords and the Crown.[169] The main business of parliament takes place in the two houses,[169] but royal assent is required for a bill to become an act of parliament (law).[170]
For general elections (elections to the House of Commons), the UK is divided into 650 constituencies, each of which is represented by a member of Parliament (MP).[171] MPs hold office for up to five years and are always up for re-election in general elections.[171] The Conservative Party, Labour Party and Scottish National Party are, respectively, the current first, second and third largest parties (by number of MPs) in the House of Commons.