The United Kingdom is a sovereign state that is made up of four constituent countries: England, Northern Ireland, Scotland, and Wales. Three of these countries; Northern Ireland, Scotland and Wales, have their own devolved legislatures and governments and are represented in some international intergovernmental organisation separately from the United Kingdom as a whole. All four countries have membership in several international sports federations and are represented by their own national teams in sports where there is no UK-wide team.
England has no devolved legislature or government and is therefore not represented in intergovernmental organisations.
Additionally, at some international sports events, athletes from Northern Ireland and the Republic of Ireland participate as part of a unified team representing the Island of Ireland.