An express warranty is any affirmation of fact or a promise made by a seller to a buyer which relates to the subject matter of the agreement and becomes a part of the basis of the bargain. It is not necessary to the creation of an express warranty that the seller use formal words such as warrant or guarantee or that the seller have a specific intention to make a warranty.

The elements of a claim for breach of express warranty for services are (1) the defendant sold services to the plaintiff; (2) the defendant made a representation to the plaintiff about the characteristics or quality of the services by affirmation of fact, by promise, or by description; (3) the representation became part of the basis of the bargain; (4) the defendant breached the warranty; (5) the plaintiff notified the defendant of the breach; and (6) the plaintiff suffered injury.

Privity (a direct relationship between the parties) is not required where the defendant furnishes samples to a middleman or makes a transferable express warranty knowing the samples or warranty will likely be submitted to the ultimate buyer.

In New Hampshire, an express warranty is created when a seller makes a specific affirmation of fact, promise, or description about the services provided, which then forms part of the contract between the buyer and seller. This warranty assures the buyer of certain aspects of the services' quality or characteristics. To establish a breach of express warranty for services in New Hampshire, a plaintiff must demonstrate that the seller sold services, made a representation about the services that became part of the contract, breached this warranty, and that the plaintiff suffered damages as a result. The plaintiff must also show that they notified the seller of the breach. Notably, New Hampshire law does not require privity of contract for a breach of express warranty claim to be valid. This means that even if the buyer was not the direct purchaser but received a transferable warranty or samples from a middleman, they may still have a claim if the seller intended for the warranty to extend to the ultimate buyer.