An individual should research existing patents before filing to ensure the invention is unique, new, and is not already protected. You can do some of this work yourself, but when developing and filing your patent application, inventors are encouraged to use the services of one of the registered attorneys and agents with the U.S. Patent Office. You can obtain a list of those names from the OSU Patent and Trademark Library or from the U.S. Patent and Trademark Office. A servicemark is defined similarly and relates to the producer of a service. To be protectable, the mark must be unique, not used by anyone else, not an unmodified generic noun or phrase, and must be used or intended to be used in commerce.
Marks represent something different than the registration of a company name.
While the company name may be a registered mark, often the company produces several products, each of which may have its own separate mark. For example, General Motors has registered GM, but it has also registered Oldsmobile, Chevrolet, etc. Before using any mark, it is important that a search be done of existing marks. This will decrease the possibility of using someone else's mark. This reduces your costs of defending the use of a mark and reduces the possibility of developing a new mark later.