When your trademark is federally registered with the USPTO it is protected throughout the United States, not just in one particular state or territory.
This is extremely useful when enforcing your trademark rights on the Internet.
Put Others on Notice.
Federal trademark registration provides nationwide constructive notice to others that the registered trademark is owned by you. If your trademark is infringed, the infringer can not defend his conduct by arguing he did not know about your trademark.
Also, when federally registered, your trademark will be published in the USPTO database. This helps prevent other parties from adopting confusingly similar trademarks.
Treble Damages + Defendant’s Profits.
When you federally register your trademark, you may be able to recover three times your actual damages (treble damages) from the trademark infringer. You may also be able to recover any profits that the defendant earned while infringing upon your trademark. These
are serious economic penalties you can use against trademark infringers, but they are only available if you federally register your trademark.
Recover Attorneys Fees
Attorneys’ fees add up fast, especially during litigation. If you have to sue a trademark infringer, you may be entitled to recover attorneys fees, but only if your trademark is federally registered.
So register your trademark, and stick the trademark infringer with your attorneys' fees.
Incontestable Status.
After five years, federally registered trademarks become “incontestable”. When this happens, your exclusive right to use the trademark is conclusively established, making it extremely difficult for another party to challenge your trademark.