tm in a trademark is the abbreviation of "trademark". A trademark is a logo used by a merchant to distinguish their products and services from those provided by others. When merchants add tm logo to the back of their trademarks, it means that merchants have started to use logo symbols and are applying for trademark registration, but they have not been approved for registration.

The tm logo in a trademark usually appears in the upper right corner next to the trademark, which tells consumers that the merchant is using the trademark, but it has not been officially approved. Merchants can add tm logo at any time when using the trademark. After the trademark is registered and approved, merchants can use R logo, which means that the trademark has been registered and approved by the Trademark Office.

tm in a trademark indicates that the trademark has not been approved for registration, while R in a trademark indicates that the trademark has been officially approved and registered in the Trademark Office. In the process of trademark use, merchants should use trademark marks correctly to avoid trademark confusion and infringement.