Hostile possession describes a person’s factual possession of land without the paper owner’s consent, and in a manner inconsistent with the owner’s title. It is a key element of adverse possession in England and Wales, Northern Ireland and Ireland, and of “possession nec precario” in Scots property law. The “hostile” element does not require aggression or ill-will; it means the occupier is in possession as of right, not by permission, lease, licence or tolerance. In practice, this often involves exclusive use, enclosure, maintenance or development of land as if the occupier were owner.In England and Wales and Northern Ireland, the concept is developed through case law on adverse possession and limitation (for example under the Limitation Act 1980 and the Limitation (Northern Ireland) Order 1989), and interacts with Land Registration legislation. In Ireland, similar principles arise under the Statute of Limitations 1957. In Scotland, case law on positive prescription and possession “adverse” to the owner fulfils an analogous role. Hostile possession is crucial when assessing whether time for adverse possession or prescription has begun to run, whether the owner has acquiesced, and whether registered or unregistered title can ultimately be displaced.