British people or Britons, also known colloquially as Brits, are the citizens and diaspora of the United Kingdom, the British Overseas Territories, and the Crown dependencies. British nationality law governs modern British citizenship and nationality, which can be acquired, for instance, by descent from British nationals. When used in a historical context, "British" or "Britons" can refer to the Ancient Britons, the Celtic-speaking inhabitants of Great Britain during the Iron Age, whose descendants formed the major part of the modern Welsh people, Cornish people, Bretons and considerable proportions of English people. It also refers to those British subjects born in parts of the former British Empire that are now independent countries who settled in the United Kingdom prior to 1973.
Though early assertions of being British date from the Late Middle Ages, the Union of the Crowns in 1603 and the creation of the Kingdom of Great Britain in 1707 triggered a sense of British national identity. The notion of Britishness and a shared British identity was forged during the 18th century and early 19th century when Britain engaged in several global conflicts with France, 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 Great Britain; Britishness became "superimposed on much older identities", of English, Scots and Welsh cultures, whose distinctiveness still resists 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.