R is the abbreviation of REGISTER, which means registered trademark when used in trademarks. The circle R is the mark of "registered trademark", which means that the trademark has been registered in the State Trademark Office and has been examined and approved by the Trademark Office.

"R" means that the registered trademark that has successfully issued the certificate is protected by law. "TM" means a trademark that is being applied for but has not issued a certificate, which is not protected by law.