Monarchy of the United Kingdom (commonly referred to as the British monarchy) is the constitutional monarchy of the United Kingdom and its overseas territories. The present monarch, Queen Elizabeth II, has reigned since 6 February 1952. She and her immediate family undertake various official, ceremonial and representational duties. As a constitutional monarch, the Queen is limited to non-partisan functions such as bestowing honours, dissolving Parliament and appointing the Prime Minister. Though the ultimate executive authority over the government of the United Kingdom is still by and through the monarch's royal prerogative, in practice these powers are only used according to laws enacted in Parliament or within the constraints of convention and precedent.
The British monarchy traces its origins from the Kings of the Angles and the early Scottish Kings. By the year 1000, the kingdoms of England and Scotland had developed from the petty kingdoms of early medieval Britain. The last Anglo-Saxon monarch (Harold II) was defeated and killed in the Norman invasion of 1066 and the English monarchy passed to the Norman conquerors. In the thirteenth century, the principality of Wales was absorbed by England, and Magna Carta began the process of reducing the political powers of the monarch.
From 1603, when the Scottish King James VI inherited the English throne as James I, both kingdoms were ruled by a single monarch. From 1649 to 1660, the tradition of monarchy was broken by the republican Commonwealth of England that followed the War of the Three Kingdoms. The Act of Settlement 1701, which is still in force, excluded Roman Catholics, or those married to Catholics, from succession to the English throne. In 1707, the kingdoms of England and Scotland were merged to create the Kingdom of Great Britain and, in 1801, the Kingdom of Ireland joined to create the United Kingdom of Great Britain and Ireland. The British monarch became nominal head of the vast British Empire, which covered a quarter of the world's surface at its greatest extent in 1921.
In the 1920s, five sixths of Ireland seceded from the Union as the Irish Free State, and the Balfour Declaration recognised the evolution of the dominions of the empire into separate, self-governing countries within a Commonwealth of Nations. After the Second World War, the vast majority of British colonies and territories became independent, effectively bringing the empire to an end. George VI and his successor, Elizabeth II, adopted the title Head of the Commonwealth as a symbol of the free association of its independent member states.
The Commonwealth includes both republics and monarchies. At present, fifteen other Commonwealth countries share with the United Kingdom the same person as their monarch. The terms British monarchy and British monarch are frequently still employed in reference to the person and institution shared amongst all sixteen of the Commonwealth realms, and to the distinct monarchies within each of these independent countries, often at variance with the different, specific, and official national titles and styles for each jurisdiction.