Adverse possession described as a person who does not have legal title to a piece of property usually land (real property) may acquire legal ownership based on continuous possession or occupation of the property without the permission (licence) of its legal owner.

The party seeking title by adverse possession may be called the disseisor, meaning one who dispossesses the true owner of the property. Although the elements of an adverse possession claim may be different in a number of states, adverse possession requires at a minimum five basic conditions being met to perfect the title of the disseisor. These are that the disseisor must openly occupy the property exclusively, in a manner that is open and notorious, continuously, and use it as if it were their own in a manner expected for the type of property.

The actions of the disseisor must change the state of the land (in the case of non-residential property, taking such actions as clearing, mowing, planting, harvesting fruit of the land, logging or cutting timber, mining, fencing, pulling tree stumps, running livestock and constructing buildings or other improvements) or, if the property is residential, maintaining the property for its intended use (taking such actions as mowing the yard, trimming trees and hedges, changing locks, repairing or replacing fixtures such as a swimming pool, sprinkler system, or appliances), all to the exclusion of its true owner.