A tour guide was an individual who provided historical, cultural, and technical information about certain landmarks and installations, usually to visiting tourist groups.
In 2372,Jadzia Dax believed she, Kor and Worf would need a Hur'q tour guide to let them into a chamber where the Sword of Kahless was hidden, as a sensor was programmed to check of for Hur'q lifesigns in order to only allow Hur'q past a force field. (DS9: "The Sword of Kahless")
In 2377, a tour guide showing a group of children the Pathfinder Project facility at Starfleet Headquarters was present when Reginald Barclay surmised that the Borg had intercepted his data stream to Voyager. (VOY: "Inside Man")