- Constitutional monarchy and Commonwealth realm
- Executive Branch: chief of state: Queen ELIZABETH II (since 6 February 1952)
- Legislative Branch: bicameral Parliament consists of House of Lords
- Juridical Branch: Supreme Court of the UK
- Head of government: Prime Minister David CAMERON (since 11 May 2010)
- 18 years of age; universal
- The UK does not celebrate one particular national holiday
- chief of mission: Ambassador Sir Nigel E. SHEINWALDchancery: 3100 Massachusetts Avenue NW, Washington, DC 20008telephone: [1] (202) 588-6500FAX: [1] (202) 588-7870consulate(s) general: Atlanta, Boston, Chicago, Houston, Los Angeles, Miami, New York, San Franciscoconsulate(s): Dallas, Denver, Orlando
- chief of mission: Ambassador Louis B. SUSMANembassy: 24 Grosvenor Square, London, W1A 1AE note - a new embassy is scheduled to open by the end of 2017 in the Nine Elms area of Wandsworth (architect Kiernan TIMBERLAKE)mailing address: PSC 801, Box 40, FPO AE 09498-4040telephone: [44] (0) 20 7499-9000FAX: [44] (0) 20 7629-9124consulate(s) general: Belfast, Edinburgh
- ADB (nonregional member), AfDB (nonregional member), Arctic Council (observer), Australia Group, BIS, C, CBSS (observer), CDB, CE, CERN, EAPC, EBRD, EIB, ESA, EU, FAO, FATF, G-20, G-5, G-7, G-8, G-10, IADB, IAEA, IBRD, ICAO, ICC, ICCt, ICRM, IDA, IEA, IFAD, IFC, IFRCS, IHO, ILO, IMF, IMO, IMSO, Interpol, IOC, IOM, IPU, ISO, ITSO, ITU, ITUC, MIGA, MONUSCO, NATO, NEA, NSG, OAS (observer), OECD, OPCW, OSCE, Paris Club, PCA, PIF (partner), SECI (observer), UN, UN Security Council, UNCTAD, UNESCO, UNFICYP, UNHCR, UNIDO, UNMIS, UNRWA, UPU, WCO, WHO, WIPO, WMO, WTO, ZC
- Army, Royal Navy (includes Royal Marines), Royal Air Force (2010)
- 16-33 years of age (officers 17-28) for voluntary military service (with parental consent under 18); women serve in military services, but are excluded from ground combat positions and some naval postings; as of October 2009, women comprised 12.1% of officers and 9% of enlisted personnel in the regular forces; must be citizen of the UK, Commonwealth, or Republic of Ireland; reservists serve a minimum of 3 years, to age 45 or 55; 16 years of age for voluntary military service by Nepalese citizens in the Brigade of Gurkhas; 16-34 years of age for voluntary military service by Papua New Guinean citizens (2009)
- 2.4% of GDP