Denization is an obsolete or defunct process in England and Ireland and the later Kingdom of Great Britain, the United Kingdom, and the British Empire, dating back to the 13th century, by which an alien (foreigner), through letters patent, became a denizen, thereby obtaining certain rights otherwise normally enjoyed only by the King's subjects, including the right to hold land. The denizen was neither a subject nor an alien, but had a status akin to permanent residency today. While one could become a subject via naturalisation, this required a private act of Parliament ; in contrast, denization was cheaper, quicker, and simpler. Denization fell into obsolescence when the British Nationality and Status of Aliens Act 1914 simplified the naturalisation process.

Permanent residency is a person's legal resident status in a country or territory of which such person is not a citizen but where they have the right to reside on a permanent basis. This is usually for a permanent period; a person with such legal status is known as a permanent resident. In the United States, such a person is referred to as a green card holder but more formally as a Lawful Permanent Resident (LPR).