Dukes in the United Kingdom
Duke, in the United Kingdom, is the highest-ranking hereditary title in all four peerages of the British Isles. A duke thus outranks all other holders of titles of nobility (marquess, earl, viscount and baron).
Peerages in the United Kingdom
Apart from hereditary peerages, there exists peerages that may be held for life and whose title cannot be passed onto someone else by inheritance. The Appellate Jurisdiction Act 1876 and the Life Peerages Act 1958 authorise the regular creation of life peerages, with the right to sit in the House of Lords. Life peers created under both acts are of baronial rank and are always created under letters patent.