UCC § 2-313
Express Warranties by Affirmation, Promise, Description, Sample
(1) Express warranties by the seller are created as follows: (a) Any affirmation of fact or promise made by the seller to the buyer which relates to the goods and becomes part of the basis of the bargain creates an express warranty that the goods shall conform to the affirmation or promise. (b) Any description of the goods which is made part of the basis of the bargain creates an express warranty that the goods shall conform to the description. (c) Any sample or model which is made part of the basis of the bargain creates an express warranty that the whole of the goods shall conform to the sample or model. (2) It is not necessary to the creation of an express warranty that the seller use formal words such as “warrant” or “guarantee” or that he have a specific intention to make a warranty, but an affirmation merely of the value of the goods or a statement purporting to be merely the seller’s opinion or commendation of the goods does not create a warranty.
Professor's notes
Three ways to make an express warranty: (1) an affirmation of fact or promise relating to the goods, (2) a description of the goods, (3) a sample or model. Each becomes part of the basis of the bargain. The seller need not use the word "warrant" or "guarantee"; an affirmation of fact suffices. An affirmation merely of the value of the goods or a statement of the seller's opinion or commendation does not create a warranty.
Common misunderstanding: students confuse warranty with puff. The line is between fact and opinion. "This truck has a rebuilt engine" is a warranty. "This is a great truck" is puff. The harder cases sit between the two. Reliance is presumed once the affirmation is part of the basis of the bargain; the seller must show the buyer did not rely.
Hawkins v. McGee is the common-law analogue: the doctor's "perfect hand" was an express warranty, not puff. Article 2 codifies the move.
Text
UCC § 2-313. Express Warranties by Affirmation, Promise, Description, Sample.
(1) Express warranties by the seller are created as follows:
(a) Any affirmation of fact or promise made by the seller to the buyer which relates to the goods and becomes part of the basis of the bargain creates an express warranty that the goods shall conform to the affirmation or promise.
(b) Any description of the goods which is made part of the basis of the bargain creates an express warranty that the goods shall conform to the description.
(c) Any sample or model which is made part of the basis of the bargain creates an express warranty that the whole of the goods shall conform to the sample or model.
(2) It is not necessary to the creation of an express warranty that the seller use formal words such as “warrant” or “guarantee” or that he have a specific intention to make a warranty, but an affirmation merely of the value of the goods or a statement purporting to be merely the seller’s opinion or commendation of the goods does not create a warranty.
Source: UCC Article 2 (post-2022 amendments), as in the LawJ statutory corpus.