A more thorough explanation:

A trade name is a type of mark that is used to identify a company, partnership, or business instead of goods or services. Unlike trademarks, trade names cannot be registered under the Lanham Act unless they are used to identify the source of specific goods or services, rather than just the company itself.

For example, "Coca-Cola" is a trade name that identifies the company that produces the popular soft drink. However, the name "Coca-Cola" cannot be registered as a trade name unless it is used to identify the source of a specific product, such as "Coca-Cola Classic" or "Diet Coke."

Trade names are generally registered at the state level, and businesses can also receive common law protection against the use of confusingly similar company names. For instance, if a new company tried to use the name "Coca-Cola" for their business, the original Coca-Cola company could take legal action to prevent them from doing so.