The United Kingdom comprises 4 constituent countries: England, Scotland, Wales, and Northern Ireland. As the first administrative level in the UK's three-tier structure, these countries serve distinct constitutional and governmental functions. Scotland, Wales, and Northern Ireland operate devolved administrations with varying degrees of legislative power over matters including health, education, housing, and transport, while England lacks a separate parliament and is governed directly by the UK Parliament. Each country maintains its own legal traditions and public service frameworks, with Scotland and Northern Ireland possessing separate legal systems from England and Wales. This arrangement reflects the UK's complex constitutional history as a union of nations rather than a unitary state with uniform regional divisions.