Two trademark symbols are in common use: The TM and the Circle-R (®).
The purpose of a trademark symbol is to let people know what words, images, etc. you consider to be your trademark. And your trademark is the thing that let’s people make a connection between your company and the goods and services that you offer.
Get a copy of 9 Secrets to Protecting Your Brand in an Online World
In the United States, you can use the TM symbol next to any word, image, etc. that you consider to be your trademark. It doesn’t have to be registered with any government (state or federal). Of course, if you do something deceptive, or are trying to infringe a trademark owned by someone else, you could still get in trouble. But the TM symbol just means “I claim this as a trademark.”
You can use the Circle-R symbol only next to a trademark that has been registered with the federal government. The federal trademark registration gives you extra legal rights. For example, if someone sues you for trademark infringement but you have a federal trademark registration, the court will assume that your trademark is valid–the other guy will have to prove that it isn’t.
The purpose of a trademark symbol is to let people know what you claim to be your trademark (or have registered as a trademark). But you don’t have to beat people over the head with it. You just need to take reasonable steps to ensure that people see the symbol once so that they are aware of the legal claim you are making. If you include a TM or Circle-R symbol on the first instance of a trademark occurring within a web page, or on a printed flyer or advertisement, that will be enough to let readers know what you consider to be your trademark.
Many other countries have similar laws to those in the US. Some businesses choose to continue using the TM symbol instead of a Circle-R even after they have registered their trademark in the US. This lets them use the same marketing materials (websites, etc.) in other countries where their trademark might not be registered yet. Using the TM symbol on a registered trademark is fine. Using a Circle-R on a non-registered trademark is not permitted.
Some companies that are confident in their branding or just dont’ like to have extraneous matter in their designs may decide not to use any symbol next to their trademark. That’s also fine. It’s not required, although there are certain legal benefits to using it, especially if not everyone might recognize that your trademark is a trademark. One alternative to using a TM or Circle-R symbol is to include a statement at the bottom of a page stating something like “MARK is a trademark and MARK2 is a registered trademark of XYZ Corp. ” It’s common to separate a list like this into registered trademark and unregistered trademarks (just listed as trademarks).