A trademark used to identify a service rather than a product is called a service mark (SM).
In the United States, service marks have a different standard of use in order to count as a use in commerce, which is necessary to complete registration and to stop infringement by competitors. A trademark normally needs to be used on or directly in association with the sale of goods, such as on a store display. As services are not defined by a concrete product, use of a service mark in advertisements is instead accepted as a use in commerce.
See also: marketing, service, certification mark.