Use well-known brands as infringement. According to relevant public information, well-known brands can only be used if they have signed contracts with designated companies, and those that have not signed contracts belong to infringement. If you use a registered trademark nickname in business activities without the authorization of the trademark registrant, it may involve trademark infringement. A trademark refers to a mark used to distinguish goods or services. Within the scope of the protection of registered trademarks, unauthorized use of trademarks will cause economic losses or damage to goodwill to the obligee, thus constituting infringement.