In common law and statutory law, a life estate (or life tenancy) is the ownership of immovable property for the duration of a person's life. In legal terms, it is an estate in real property that ends at death, when the property rights may revert to the original owner or to another person. The owner of a life estate is called a "life tenant". The person who will take over the rights upon death is said to have a "remainder" interest and is known as a "remainderman".

The ownership of a life estate is of limited duration because it ends at the death of a person. Its owner is the life tenant (typically also the 'measuring life') and it carries with it right to enjoy certain benefits of ownership of the property, chiefly income derived from rent or other uses of the property and the right of occupation, during his or her possession. Because a life estate ceases to exist at the death of the measuring person's life, the life tenant, a temporary owner, may short-term let but cannot sell, give or bequeath the property indefinitely (including assuming it could pass to heirs (intestate)) or creating a purported document leaving it to devisees (testate).

A life estate pur autre vie (Law French, "for the life of another") is held for the rest of the lifetime of a person who does not hold the estate, known as the cestui que vie (Law French, "the person who lives"). This form of life estate arises where a life tenant has disposed of the property, assuming such a disposal does not trigger any special forfeiture under the life interest instrument. It also arises where the grantor chooses to make the measuring life that of someone other than the life tenant's life. A life estate pur autre vie is most commonly created in one of two circumstances.

A clear distinction should be made with an estate for (a) term of years, interpreted as lease or licence.

At death, assuming no mis-dealings to certain innocent purchasers, the property involved in a life estate falls into the ownership of the remainderman (pl. remaindermen) or reverts to its grantor (all of which confusingly can be called 'reversions' and 'reversioners'). There is a small market for reversions in real estate, which necessitates a buyer to carry out enhanced documentary due diligence and physical checks.

A land owner of an estate cannot give a "greater interest" in the estate than he or she owns. That is, a life estate owner cannot give complete and indefinite ownership (fee simple) to another person because the life tenant's ownership in the property ends when the person who is the measuring life dies. For instance, if Ashley conveyed to Bob for the life of Bob, and Bob conveys a life estate to another person, Charlie, for Charlie's life [an embedded life estate], then Charlie's life estate interest would last only until Charlie or Bob dies. Charlie's life interest or pur autre vie interest (interest for the life of another, whichever has applied) and most often the remaining rights of ownership in the property (the 'reversionary interest') devolve to the persons under the terms of the will/rules of intestacy/declaration of trust/trust deed (UK) or will/rules of intestacy/'grant or deed of life interest' (or similar) (U.S.) in remainder or revert to the original grantee, depending on terms of Ashley. Such a life estate in the U.S. can also be conveyed for the life of the grantor, such as "A conveys X to B until A dies" and in the UK by trust transferring upon trust or assigning rather than conveying X.

If a life tenant purports to transfer the underlying 'reversionary' interest, which a life tenant never has, this constitutes an actionable breach of trust for damages and may constitute criminal fraud however may not entitle the ultimate reversioner (or substituted beneficiaries) to be able to obtain a court declaration that the property is their own if that property is in the hands of an innocent purchaser for value without notice (bona fide purchaser).

Financial and physical responsibility falls to the life tenant under the legal doctrine of waste, which prohibits life tenants from damaging or devaluing the asset. In short, as the life tenant's ownership is temporary, failing to maintain or reasonably protect the asset resulting in its diminution in value, or indeed, destruction constitutes a cause of action for the reversioner.