The best way to protect your trademark is to register it with the USPTO if you are in the United States, or with the relevant registration body of your country. If you do not register your trademark, others may be able to use the same or similar trademark.
Technically, trademark registration is not required to protect your rights in the United States. However, registered trademarks enjoy additional rights and remedies.
For more information about registering your trademark with the USPTO, visit: https://www.uspto.gov/