United Kingdom

The United Kingdom is a country on islands.

It has four parts. They are England, Scotland, Wales and Northern Ireland. The sea is almost all around it. The capital city is London.

The United Kingdom, often called the UK, is an island country off the northwest coast of mainland Europe. It is made of four parts: England, Scotland and Wales, which share the big island of Great Britain, and Northern Ireland, in the north of the island of Ireland.

About 69.5 million people lived in the UK in 2025, and its capital is London, on the River Thames. No place in the UK is more than 120 kilometers from the sea.

The United Kingdom of Great Britain and Northern Ireland holds most of the area and population of the British Isles. Great Britain contains England, occupying most of the south, Scotland in the north and Wales in the west; Northern Ireland occupies the northern part of the island of Ireland. The total area is about 242,500 square kilometers, roughly the size of the U.S. state of Oregon.

The Office for National Statistics estimated the population at 69,483,900 in mid-2025, an increase of 0.3 percent on the year before and the slowest growth since mid-2020. The UK is a constitutional monarchy and parliamentary democracy: the monarch is head of state, while the prime minister, who leads the majority party in the elected House of Commons, heads the government. Its constitution is uncodified, drawn from laws passed by Parliament, court decisions and other sources rather than one written document.

London is the biggest city in the UK.

A big river called the Thames flows through it. Tower Bridge goes over the river. Edinburgh is a city in Scotland with a castle on a hill.

London, the capital, is one of the world's leading centers for business and culture, and it had about 8.8 million people at the 2021 census. It stands on the River Thames. Beside the river is the Tower of London, a fortress built around the White Tower, which William the Conqueror built to protect the city.

Each part of the UK has its own capital city: Edinburgh in Scotland, Cardiff in Wales and Belfast in Northern Ireland. Edinburgh has two different historic areas, the Old Town below a medieval castle and the New Town, built from the 1700s onward. Other big cities include Birmingham, Manchester, Liverpool and Glasgow.

London, on the tidal River Thames in southeastern England, is among the world's leading commercial, financial and cultural centers; the city had about 8.8 million people in 2021. UNESCO inscribed the Tower of London in 1988: its massive White Tower, built by William the Conqueror to protect London and assert his power, is a typical example of Norman military architecture, and the later fortress grew around it.

Edinburgh has been Scotland's capital since the 15th century. Its Old Town is dominated by a medieval fortress, while the neoclassical New Town, developed from the 18th century, had a far-reaching influence on European town planning; both became a World Heritage Site in 1995. Cardiff is the capital of Wales and Belfast of Northern Ireland, and Britannica lists Birmingham, Liverpool, Manchester, Glasgow, Swansea and Londonderry among the other major cities.

The UK has green hills and rocky mountains.

The tallest mountain is Ben Nevis in Scotland. On one coast there are thousands of stone columns. It rains a lot in the mountains in the west.

Great Britain is often split into a highland zone in the north and west and a lowland zone in the south and east. The highest mountain is Ben Nevis in Scotland, about 1,345 meters tall; that is low compared with Europe's big ranges.

On the coast of Northern Ireland, the Giant's Causeway is made of about 40,000 black stone columns. They formed from volcanic activity 50 to 60 million years ago. Rain arrives mostly from the west, so the western mountains are very wet, while parts of eastern England stay much drier.

Great Britain is traditionally divided into a highland zone of older rocks in the north and west and a lowland zone of younger strata in the southeast, roughly along a line from the River Exe to the Tees. Elevations are modest: Ben Nevis, the highest summit, is 1,345 m by Ordnance Survey's 2016 GPS survey (Britannica still gives the older 1,343 m), Snowdon (Yr Wyddfa) reaches 1,085 m in Wales and Scafell Pike 978 m in England. Lough Neagh in Northern Ireland is the largest freshwater lake in the British Isles.

The Giant's Causeway, at the foot of the basalt cliffs of the Antrim plateau, consists of some 40,000 basalt columns formed by volcanic activity in the Tertiary, about 50–60 million years ago; UNESCO inscribed it in 1986. Westerly winds off the relatively warm Atlantic bring most of the rain: the highest peaks can receive up to 5,100 mm a year, while Norfolk, Suffolk and the Thames estuary may get as little as 510 mm. Mean annual temperature ranges from about 8 °C in the Hebrides to 11 °C in southwestern England.

About 69 million people live in the UK.

Most of them live in England. Most people speak English. In Wales, many people also speak Welsh. Families from many countries live in the UK.

About 69.5 million people lived in the UK in 2025. Most, about 58.8 million, lived in England, with about 5.5 million in Scotland, 3.2 million in Wales and 1.9 million in Northern Ireland.

English is an official language in every part of the UK, and some older languages are still alive: Welsh is official in Wales too, and Scottish Gaelic in Scotland. About one in five people in Wales can speak Welsh, and Scottish Gaelic is spoken most on islands such as Skye and the Outer Hebrides. Since the 1950s, many people have moved to the UK from the Caribbean, South Asia and other places.

Mid-2025 estimates put England at 58,834,800 people, Scotland at 5,545,500, Wales at 3,175,200 and Northern Ireland at 1,928,400. Net international migration was the main driver of growth; in Wales and Scotland, deaths outnumbered births. The median age was 43.2 in Wales, 43.1 in Scotland and 40.6 in England and Northern Ireland.

Modern English descends mainly from the Germanic dialects of the Angles, Saxons and Jutes, who arrived in the 5th century, and was heavily shaped by Danish and Norman French. Of the Celtic languages, Welsh is strongest, spoken by about one-fifth of the people of Wales; fewer than 2 percent of Scots speak Gaelic. Large West Indian and South Asian communities date from the 1950s and 1960s, and people of Indian, Pakistani and Bangladeshi origin make up more than half of the ethnic minority population.