In contract law, a warranty is a contractual assurance given by a seller to a buyer, for example confirming that the seller is the owner of the property being sold. A warranty is a term of a contract, but not usually a condition of the contract or an innominate term, meaning that it is a term "not going to the root of the contract", and therefore only entitles the innocent party to damages if it is breached, i.e. if the warranty is not true or the defaulting party does not perform the contract in accordance with the terms of the warranty. A warranty is not a guarantee: it is a mere promise. It may be enforced if it is breached by an award for the legal remedy of damages.

Depending on the terms of the contract, a product warranty may cover a product such that a manufacturer provides a warranty to a consumer with whom the manufacturer has no direct contractual relationship because it is purchased via an intermediary.

A warranty may be express or implied. An express warranty is expressly stated (typically, written); whether or not a term will be implied into a contract depends on the particular contract law of the country in question. Warranties may also state that a particular fact is true at a point in time, or that the fact will continue into the future (a "continuing warranty").