Adverse possession is a situation when a person who does not have legal title to land (or real property) occupies the land without the permission of the legal owner. The permission of the owner may be reflected in the entering into a lease or granting a licence, typically associated with the payment of some rent. The laws of many countries allow the adverse possessor (in law also called the disseisor) to acquire title to the land after a prescribed statutory period, which varies between jurisdictions, and depend on the type of land and other circumstances. The laws of most jurisdictions do not permit claims of adverse possession against public land. Squatting is a form of adverse possession. The adverse possessor is usually required to prove non-permissive use which is actual, open and notorious, exclusive, adverse, and continuous for the statutory period. If a claim to title by adverse possession is successful, title is acquired without compensation.
The circumstances in which adverse possession arises determine the type of title acquired by the disseisor, which may be fee simple title, mineral rights, or another interest in real property. Adverse possession's origins are based both in statutory actions and in common law precepts, so the details concerning adverse possession actions vary by jurisdiction. The required period of uninterrupted possession is governed by the statute of limitations. Other elements of adverse possession are judicial constructs.
Chattel property may also be adversely possessed, but owing to the differences in the nature of real and chattel property, the rules respecting such claims are rather more stringent, favoring the legal owner rather than the adverse possessor/disseisor; such rules find particular application respecting works of art.
In Roman law, usucapio laws allowed someone who was in possession of a good without title to become the lawful proprietor if the original owner didn't show up after some time (one or two years), unless the good was obtained illegally (by theft or force). Stemming from Roman law and its successor, the Napoleonic Code adopted as the basis of law in France, Belgium, Italy, Luxembourg, Portugal, Spain and also in part, by the Netherlands and Germany, adverse possession generally recognizes two time periods for the acquisition of property: 30 years and some lesser time period, depending on the bona fides of the possessor and the location of the parties involved.