A more thorough explanation:

Trademark registration is the process of establishing legal rights to a particular mark that is used in commerce. This process is not required, but it provides stronger and broader protections than an unregistered trademark. Registering a trademark with the United States Patent & Trademark Office (USPTO) offers several advantages, including:

• Notice to the public of the owner's claim of ownership of the mark
• A legal presumption of ownership nationwide
• The exclusive right to use the mark on or in connection with the goods or services listed in the registration
• The ability to bring an action concerning the mark in federal court
• The use of the U.S. registration as a basis to obtain registration in foreign countries
• The ability to file the U.S. registration with the U.S. Customs and Border Protection (CBP) to prevent importation of infringing foreign goods

In order to register a trademark, the mark must meet three requirements:

1. First use in a particular trade or geographic market
2. Non-functionality
3. Distinctiveness

For example, the Nike "swoosh" logo is a registered trademark because it is distinctive and not functional. However, the word "shoe" cannot be registered as a trademark because it is too generic.

Traditionally, derogatory references and immoral names could not be trademarked. However, in the case of Matal v. Tam, the U.S. Supreme Court found that the disparagement clause of the Lanham Act, which prohibited federal trademark registration for disparaging marks, was invalid under the First Amendment. This means that even potentially offensive or controversial marks can now be registered as trademarks.