A trademark is always connected to the specific goods or services sold to customers with that trademark. You can’t register a word, phrase, symbol, or design as a trademark without specifically identifying the goods or services being used. Your trademark isn’t limited to one good or service. It can be used with many different goods or services, and include both goods and services.

Although the determination of whether you have goods or services can be confusing, it’s critical that you make the correct identification. Think about it this way: What do customers purchase from you? An actual physical product that bears your trademark? Or do they hire you to perform an activity for them? If it’s products, you have goods. If it’s activities, you have services.

For example, a registered trademark for the name A Good YarnTM for a bookstore would prevent another company from registering the name A Good YarnTM for another bookstore.

By being specific about the goods or services your trademark represents in your registration, you clearly identify the scope of use. You can legally prevent others from using the same or a similar trademark for related goods or services without your permission. Applying for more goods or services than you currently use, or intend to use, is likely to cause your application to be denied. We may inquire as to whether the identification you select accurately identifies your goods or services.

https://www.uspto.gov/trademarks/basics/scope-protection