In commercial and consumer transactions, a warranty is a collateral assurance or guarantee that certain facets of an article or service sold is as factually stated or legally implied by the seller, and that often provides for a specific remedy such as repair or replacement in the event the article or service fails to meet the warranty.[1] A breach of warranty occurs when the promise is broken, i.e., a product is defective or not as should be expected by a reasonable buyer.

In business and legal transactions, a warranty is an assurance by one party to the other party that certain facts or conditions are true or will happen; the other party is permitted to rely on that assurance and seek some type of remedy if it is not true or followed.

In real estate transactions, warranty deed is a promise that the buyer's title to a parcel of land will be defended.

A warranty may be express or implied.