This chapter explores the UK as a state which is made up of a number of diverse parts. These parts are Wales, Scotland, England, and the territory of Northern Ireland. Each part has its own characteristics which show through in the political and constitutional makeup of the UK as a whole. The chapter describes these different components. It discusses the various differences between them and looks at issues related to maintaining coherence. Using theoretical models, it analyses the nature of the UK as the state, the nation state, and the multinational state. It looks at the concepts of consociationalism, the unitary state, the union state, and federation. It provides a number of practical examples which demonstrate how these ideas operate in the real world. It also considers the Welsh language, territorial variation in the party system, the ‘English Votes for English Laws’ procedure in the UK House of Commons; and the ‘Barnett’ formular for the allocation of funding in the UK.