The symbol ® is a notice of registered ownership used in many countries or regions to advise the public that a trademark or service mark is registered and to provide constructive notice of the legal ownership status of the mark with which it is used. The ® symbol should be used only in connection with registered trademarks or service marks. In the United States, use of ® may be instituted only after registration of the mark is granted. Use of ® with an unregistered mark may result in claims of fraud where the owner demonstrates intent, knowing and willful misuse, and attempts to deceive or mislead consumers, or in other difficulties for the owner in trying to obtain and/or enforce its trademark rights.

Reference: International Trademark Association