Warranty period refers to the period during which the contractor is responsible for the warranty of the completed project after the project is completed. The warranty period is stipulated in the contract. The warranty period starts from the date when the Owner's engineer issues the project completion certificate. The tasks of the contractor during the warranty period are: (1) to complete the remaining work when the project completion certificate is issued; (2) Repair, modify, rebuild, correct and repair the problems found by the project owner during the use and warranty period. Make the project meet the contract requirements and hand it over to the owner. The cost of repair work. If the materials or operation techniques used in the construction do not meet the requirements of the contract, or the contractor neglects or fails to comply with the obligations stipulated in the contract during the construction, the relevant expenses shall be borne by the contractor. If the owner's engineer thinks that the necessary maintenance is due to other reasons (such as the damage of the project owner in use), the cost will be paid as additional work after verification by the project owner. Upon the expiration of the project warranty period, the owner's engineer will issue a maintenance certificate after the final acceptance of the project owner. This maintenance certificate is the final acceptance certificate of the project.

Generally, after the consumer and the merchant complete the transaction, the merchant will handle the warranty card with the product as the warranty certificate for the consumer.

Generally, it is consumer information, purchase date, product model, factory date, warranty period and scope, maintenance records, etc. It will be indicated on the warranty certificate. There are two kinds of warranty: a certain period of warranty and a lifetime warranty. Products with warranty mainly refer to electronic and electrical products, vehicles, machinery and equipment, etc. Powerful companies also pay more attention to the influence of after-sales service on efficiency. Products with good after-sales service include national warranty, multinational company and global warranty service.