In property law, alienation is the voluntary act of an owner of some property to dispose of the property, while alienability, or being alienable, is the capacity for a piece of property or a property right to be sold or otherwise transferred from one party to another. Most property is alienable, but some may be subject to restraints on alienation.

In England under the feudal system, land was generally transferred by subinfeudation, and alienation required license from the overlord. When William Blackstone published Commentaries on the Laws of England between 1765-1769, he described the principal object of English real property laws as the law of inheritance, which maintained the cohesiveness and integrity of estates through generations and thus secured political power within families. In 1833, Justice Joseph Story in his Commentaries on the Constitution of the United States linked landowners' jealous watchfulness of their rights and spirit of resistance in the American Revolutionary War with the system of American institutions which recorded and clarified land title and expanded landed markets. Other early American legal commentators who praised the simple and relatively inexpensive conveyancing system in the new United States included Zaphaniah Swift, Daniel Webster and James Kent.

Some objects are now regarded as being incapable of becoming property and thus termed inalienable, such as people and body parts.

Aboriginal title is one example of inalienability (save to the Crown) in common law jurisdictions. A similar concept is non-transferability, such as tickets. Rights commonly described as a license or permit are generally only personal and are not assignable. However, they are alienable in the sense that they can generally be surrendered.

An estate in land is an interest in real property that is or may become possessory. It is a type of personal property and encompasses land ownership, rental and other arrangements that give people the right to use land. This is distinct from sovereignty over the land, which includes the right to government and taxation.

This should be distinguished from an "estate" as used in reference to an area of land, and "estate" as used to refer to property in general.

In property law, the rights and interests associated with an estate in land may be conceptually understood as a "bundle of rights" because of the potential for different parties having different interests in the same real property.