TM, SM, and ® - what do they mean? TM and SM are used for unregistered trademarks and service marks, respectively. However, the ® symbol indicates that a mark is registered with the U.S. Patent and Trademark Office (USPTO).
While TM and SM are not legally necessary to establish common law trademark rights (you get those when you use your product or service in commerce), they can provide a variety of benefits like showing the public that a descriptive term is actually the source of a product (e.g., QUIET™ vacuum; YUMMY™ snacks) or to illustrate which words or symbols on a label you actually consider to be a trademark. However, nothing is more beneficial for your mark in the United States than registering it with the USPTO, which can provide a number of advantages over common law rights, including "[a] legal presumption of your ownership of the mark and your exclusive right to use the mark nationwide."
Check out this link for basic facts about trademarks from the USPTO.