When and how can one party use another's trademark?
Appropriate use of a trademark is important to comply with federal law (and if applicable, state law). Trademarks include words, symbols or designs that specifically identify and distinguish the source of an owner's commercial goods. This means uses of the trademark that are likely to confuse the public as to whether the use is made by the owner or by another are generally prohibited.
Some trademark owners assume no one else has a right to independently use the mark in any capacity whatsoever. This is not necessarily true. One can refer to a trademark for a legitimate, noninfringing purpose as long as no more of the trademark is being used than is necessary for this purpose. Generally, trademark laws merely control commercial use of the name.
Under the trademark version of "fair use" doctrine, the more common and generic the word(s) are or have become in the English language, the less likely the trademark owner may be able to regulate them. This doctrine also protects "nominative" use of the trademark name, as is often done by competitors in marketing materials.
Trademark owners often have their own policies as to how their trademark may be used. Here are some typical ways in which use of a trademark by a non-owner might be authorized: