The differentiation of English into separate varieties in the regions of Britain and Ireland has a long history. This is connected with the separate but related identities of England, Wales, Scotland, and Ireland. In this chapter the main linguistic traits of the regions are described and discussed within the framework of language variation and change, an approach to linguistic differentiation that attempts to identify patterns of speaker social behavior and trajectories along which varieties develop. The section on England is subdivided into rural and urban forms of English, the former associated with the broad regions of the North, the Midlands, East Anglia, the Southeast and South, and the West Country. For urban varieties English in the cities of London, Norwich, Milton Keynes, Bristol, Liverpool, and Newcastle upon Tyne is discussed in the light of the available data and existing scholarship. English in the Celtic regions of Britain and Ireland is examined in dedicated sections on Scotland, Wales, and Ireland. Finally, varieties of English found on the smaller islands around Britain form the focus, i.e., English on the Orkney and Shetland islands, the Isle of Man, and the Channel Islands.