Fee simple, also known as fee simple absolute, is a term of art in common law. It is most common way real estate is owned in common law countries, and is the most complete ownership interest one can have in real property. In common law legal terminology, one does not "own" the real estate; one has an estate in the land conferring certain rights. The fee simple estate is also called "estate in fee simple" or "fee-simple title."
Having its origins in feudalism, one who has a fee simple interest has complete dominion over the real property. According to William Blackstone, the great common law commentator, fee simple is the estate in land which a person has when the lands are given to him and his heirs, absolutely, without any end or limit put to his estate. Land held in fee simple can be conveyed to whomever its owner pleases; it can be mortgaged or put up as security as well. No rent or similar obligations are due from the owner of property in fee simple.
Fee simple can be contrasted with a life estate, which is an interest in lands that terminates upon the owner's death, and reverts to the grantor or the grantor's heirs according to the terms of the instrument. It also was formerly contrasted with fee tail, traditionally created by the words of grant "to N. and the heirs of his body"; under fee tail, the owner could not alienate the property, which was supposed to be passed on to the direct descendants of the owner.
Other estates in land include the fee simple conditional, the fee simple defeasible, the fee simple determinable, the fee simple subject to a condition subsequent, the fee simple subject to an executory limitation, and the life estate.