If a mark is registered with the USPTO (or with certain other countries’ trademark offices), the “circle R” or ® can be used. As the USPTO explains, improper use of the ® symbol can lead to problems. If a mark is not registered, but the owner claims common law rights, you may see a “TM” or “SM” – with “TM” referring to a trademark (for goods) and “SM” referring to a service mark (for services).
The “Circle C” or © symbol refers to copyrights, which are original works of authorship, like books, photographs, and artwork. As the Copyright Office explains, “[t]he use of a copyright notice is the responsibility of the copyright owner and does not require permission from, or registration with, the Copyright Office.”