The United Kingdom of Great Britain and Northern Ireland was created when the Kingdoms of England and Scotland -- which previously had been distinct states under a single monarchy -- were joined under the 1701 Acts of Union. The island of Ireland was incorporated under the 1800 Acts of Union, while Wales had been part of the Kingdom of England since the 16th century. The United Kingdom has historically played a leading role in developing parliamentary democracy and in advancing literature and science. The 18th and 19th centuries saw the rapid expansion of the British Empire despite the loss of the Thirteen Colonies, and at its zenith in the early 20th century, the British Empire stretched over one fourth of the earth's surface. The first half of the 20th century saw two World Wars seriously deplete the UK's strength and the Irish Republic withdraw from the union. The second half witnessed the dismantling of the Empire and the UK rebuilding itself into a modern and prosperous European nation. As one of five permanent members of the UN Security Council and a founding member of NATO and the Commonwealth of Nations, the UK pursues a global approach to foreign policy. The devolved Scottish Parliament, the National Assembly for Wales, and the Northern Ireland Assembly were established in 1998.

The UK was an active member of the EU after its accession in 1973, although it chose to remain outside the Economic and Monetary Union. However, motivated in part by frustration at a remote bureaucracy in Brussels and massive migration into the country, UK citizens in 2016 voted by 52 to 48 percent to leave the EU. On 31 January 2020, the UK became the only country to depart the EU -- a move known as "Brexit" -- after prolonged negotiations on EU-UK economic and security relationships.

UK Space Agency (UKSA; established in 2010); the UKSA replaced the British National Space Center (BNSC; organized in 1985); UK Space Command (formed 2021) (2024)

Has a comprehensive space program and is active across all areas of the space sector outside of launching humans into space, including satellite/space launch vehicles (SLVs)/rockets and their components, space probes, satellites and satellite subcomponents, space sensors, spaceports, and various other space-related technologies; as a founding member of the European Space Agency (ESA), it is heavily involved in ESA programs and has bi-lateral relations with many members; is a close partner of the US NASA and since 2016 has forged over 350 relationships with international organizations across nearly 50 developing countries; has a large commercial space sector that produces SLVs, SLV components, satellites, satellite subcomponents and sensors, and other space-related technologies; the UK has a space industrial plan, and the UKSA has provided funding to encourage and support commercial space projects (2024)