A warranty is a promise made by the seller to the buyer regarding the quality of the product. If the product does not function properly, then the seller is liable to repair or replace the product, without any expense to the customer. It also specifies a certain time limit to redeem the warranty.

There are two basic types of warranties -- implied warranties and express warranties. Implied warranties simply mean that the moment a sale is made, the seller automatically makes the promise that the product is in proper condition and there are no known defects present in it. Also, if later it is found that there are any problems, it is the manufacturers duty to fix or replace the product.

If the seller also makes any specific promise to the customer related to the product, and the product fails to deliver, it is still considered a breach of promise.

These warranties are assurances of the quality of the product at the time of sale and not how long it will last. Also, there are limitations on what can be claimed under the warranty. Any kind of mishandling or abuse of the product is generally not covered. Also, wear and tear due to regular use of the product may also not be covered under a warranty. This again could be product specific.

Sometimes, a warranty is applicable to used products, as well -- depending upon its type and price. If a seller does not want to offer any warranties, he has to notify the customer in advance. This is known as selling the product "as is".Of course, this may deter a customer from buying the product.

The seller may voluntarily offer an express warranty to a customer. This may be a part of a promotion or advertisement campaign.