A trademark is anything that indicates source, sponsorship, affiliation, or other relation of a product or service to a business. The specific identity of the business does not need to be known. Trademark protection lasts as long as the trade dress or trademark indicates source. This generally means that the protection lasts as long as the trademark or trade dress is being used with some exceptions.
Registrations require renewal.
Trademark law prevents consumer confusion as to the source of products or services. There is a second minor trend that trademarks are like property and diminishment of value is basis for an infringement action. Common law trademarks, i.e., unregistered, exist in the area in which the mark is being used or is known. State registrations exist throughout the state. Federal registrations exist throughout the country.