The British (also known as Britons, informally Brits or Britishers) are citizens of the United Kingdom, of the Isle of Man, any of the Channel Islands, or of any of the British overseas territories, and their descendants. British nationality law governs modern British citizenship and nationality, which are acquired, for instance, by birth in the UK or by descent from British nationals. When used in a historical context, the term British people refers to the ancient Britons, the indigenous inhabitants of Great Britain south of the Forth.

Although early assertions of being British date from the Late Middle Ages, the creation of the United Kingdom of Great Britain in 1707 triggered a sense of British national identity. The notion of Britishness was forged during the Napoleonic Wars between Britain and the First French Empire, and developed further during the Victorian era. The complex history of the formation of the United Kingdom created a "particular sense of nationhood and belonging" in Britain; Britishness became "superimposed on much older identities", of English, Scots and Welsh cultures, whose distinctiveness still resist notions of a homogenised British identity. Because of longstanding ethno-sectarian divisions, British identity in Northern Ireland is controversial, but it is held with strong conviction by unionists.