Technically, a trademark does not have to be registered with the federal government to exist, although there are benefits to registration. An unregistered trademark that contains a word, phrase, slogan or product name is identified by the letters TM or SM immediately following it, usually in superscript. The TM designation means a mark that applies to goods, while the letters SM stand for "service mark," to indicate a trade or service used in commerce. If the trademark is registered, the letter R appears in a circle.
Marks of Distinction
The most distinctive trademarks identify the source of goods or services by association or suggestion, as opposed those that describe a product or make a generic reference to it. For example, “Apple” is a successful trademark because it refers to a brand of computer, but it wouldn’t cut it as a brand name for the fruit of the same name.
Other Identifying Elements
Even in the absence of TM and the registered trademark symbols, it’s still fairly simple to identify a trademark by its presentation. Unique spellings and capitalizations point to a trademark, as in “Brite-Lite” and “LITE-BRITE”; the former represents a distributor of electronics, and the latter represents a child’s toy.
The standard practice is to treat the mark as an adjective, not a verb or noun, a lesson taught to the Otis Elevator Company in the landmark case, Haughton Elevator Co. v. Seeberger. In 1900, an employee of the company named Charles Seeberger secured U. S. trademark No. 34,724 for the word “Escalator,” the brand name given to his newly invented moving stairway. Unfortunately, because the company often used the word in advertisements to refer to "an Escalator," as opposed to an "Escalator brand moving stairway," the word became associated with the actual device rather than its source, the manufacturer. As a result, the company lost all rights to the trademark in 1950 and the word remains in the public domain today.