Fee simple is an ownership interest in real property that is the most full, unlimited, and absolute property interest recognized by law. This ownership interest of title in fee simple is also referred to as fee simple absolute; estate in fee simple; fee simple title; or simply fee, and the term is usually used to indicate the real property ownership interest a seller is transferring to a buyer.

The rights of a fee simple property owner are limited by the government’s power to tax the land (property taxes) and to purchase the land through the compulsory process mandated by state law—often as provided in the state’s constitution or in the state’s statutes—which is known as eminent domain.

In limited circumstances fee simple ownership may also be subject to the state’s police powers, the law of escheat (when the property owner dies without a will and without heirs), and encumbrances or deed restrictions on the use of the land.

In New Hampshire, fee simple ownership represents the most comprehensive type of real estate ownership. As a fee simple owner, one has the right to possess, use, and dispose of the property as they wish, subject to certain limitations. These rights are subject to governmental powers such as taxation, where the government can levy property taxes on the land. Additionally, the government may exercise its power of eminent domain to compel the sale of the property for public use, in accordance with New Hampshire statutes and potentially the state constitution. Fee simple ownership may also be limited by the state's police powers, which allow for regulations in the interest of public health, safety, and welfare. Furthermore, if a property owner passes away intestate (without a will) and without heirs, the property may escheat, or revert, to the state. Lastly, the use of fee simple property can be restricted by encumbrances or deed restrictions, which are conditions placed on the property that limit its use or the owner's ability to convey it.