There are essentially two categories or types of trademarks honored in the United States — registered and unregistered.
Registered Trademark: Is recognized on the U.S. Principal Register and can have a few advantages over an unregistered mark. For example, a registered trademark provides a legal presumption of ownership, which can be a huge help in the event of a trademark dispute. The registered mark makes it easier to file suite against copycats. And registering a mark in the U.S. can help if you want to extend the trademark to other nations. Registered U.S. trademarks use the registered symbol (®).
Unregistered Trademark: Can be used by any business, assuming it is eligible to be a trademark. To identify an unregistered trademark, simply place the trademark symbol (™) after or on the brand name, advertising slogan, or graphic design.
Displaying the unregistered trademark with the associated symbol on a website, in emails, on invoices, and on packing slips constitutes use. That is all that is required for unregistered trademarks in the U.S.
In the event of a dispute over a trademark, the company that first used the trademark will win in most circumstances.