Trademark symbols are useful to notify third-parties that the owner claims trademark rights, or that a trademark is registered. Practically, use of the designation deters infringement.
® Circle-R symbol means that a trademark is registered. The circle-R can be used after the trademark is registered. It cannot be used while a trademark registration is pending.
™ means the owner claims trademark rights. The TM symbol can be used for an unregistered trademark or a registered trademark.
℠ symbol means the owner claims service mark rights. The SM symbol can be used for an unregistered or registered service mark.