As part of the trademark application process, almost all marks must be used to eventually be registered. The Trademark Office requires that a trademark applicant submit evidence in the application showing acceptable use of the mark. This evidence is called a specimen, and there are many requirements for what it must show.
The Trademark Office yesterday released examination guidelines for Service Mark Specimens, which attempts to describe the elements of an acceptable specimen for services, discusses specific issues and potential refusals, addresses commonly submitted specimens for modern technology-related services, and provides examples of acceptable and unacceptable specimens. The examination guidelines are manuals for trademark examiners to use when evaluating a trademark application, and together, with the TMEP and other trademark laws and rules, inform how an application is received and analyzed. You can read the new guidelines here.