Many owners like to put a “TM” (or “SM” for service mark) next to their mark to let the world know that they are claiming ownership of it. There is no legal necessity for providing this type of notice, however, because the use of the mark itself is the act that confers ownership.
The “R” in a circle ( ) is a different matter entirely. This notice may not be put on a mark unless it has been registered with the U.S. Patent and Trademark Office. The failure to put the notice on a mark that has been so registered can result in a handicap if it later becomes necessary to file a lawsuit against an infringer of the mark.
Related terms: registered mark; TM; unregistered mark, protection of.