Allodial title constitutes ownership of real property (land, buildings, and fixtures) that is independent of any superior landlord. Allodial title is related to the concept of land held "in allodium", or land ownership by occupancy and defense of the land. Historically, much of land was uninhabited and could, therefore, be held "in allodium".

Most property ownership in common law jurisdictions is fee simple. In the United States, the land is subject to eminent domain by federal, state and local government, and subject to the imposition of taxes by state and/or local governments, and there is thus no true allodial land. Some states within the U.S. (notably, Nevada and Texas) have provisions for considering land allodial under state law, and the term may be used in other circumstances. Land is "held of the Crown" in England and Wales and other jurisdictions in the Commonwealth realms. Some land in the Orkney and Shetland Islands, known as udal land, is held in a manner akin to allodial land in that these titles are not subject to the ultimate ownership of the Crown.

In France, while allodial title existed before the French Revolution, it was rare and limited to ecclesiastical properties and property that had fallen out of feudal ownership. After the French Revolution allodial title became the norm in France and other civil law countries that were under Napoleonic legal influences. In October 1854, the seigneurial system of Lower Canada, which had been ceded from France to Britain in 1763 at the conclusion of the Seven Years' War, was extinguished by the Seigneurial Tenures Abolition Act of October 1854, and a form similar to socage replaced it.

Property owned under allodial title is referred to as allodial land, allodium, or an allod. In the Domesday Book it is called alod. Historically, allodial title was sometimes used to distinguish ownership of land without feudal duties from ownership by feudal tenure which restricted alienation and burdened land with the tenurial rights of a landholder's overlord or sovereign.