The Parliament of Great Britain was formed in 1707 following the ratification of the Treaty of Union by Acts of Union passed by the Parliament of England and the Parliament of Scotland. At the start of the nineteenth century, Parliament was further enlarged by Acts of Union ratified by the Parliament of Great Britain and the Parliament of Ireland that abolished the latter and added 100 Irish MPs and 32 Lords to the former to create the Parliament of the United Kingdom of Great Britain and Ireland. The Royal and Parliamentary Titles Act 1927 formally amended the name to the "Parliament of the United Kingdom of Great Britain and Northern Ireland", five years after the secession of the Irish Free State.

The UK parliament and its institutions have set the patterns for many democracies throughout the world, and it has been called "the mother of parliaments".