'The United Kingdom of Great Britain and Northern Ireland' is the official title of the state; this is often referred to briefly as 'Britain'.

'Great Britain' comprises England, Wales and Scotland.

Some relevant dates of British history:

1536-42: Acts of Union integrate England and Wales administratively and legally and gives Wales representation in Parliament

1603: Union of the crowns of Scotland and England under James VI of Scotland

1707: Acts of Union unite the English and Scottish parliaments

1801: Act of Union unites Great Britain and Ireland

1921: Anglo-Irish Treaty establishes the Irish Free State; Northern Ireland remains part of the United Kingdom

1999: Scottish Parliament, National Assembly for Wales and Northern Ireland Assembly assume their devolved powers.