Ratings were a measurement of television viewership.
In 2024, after Jadzia Dax pleaded with him, Christopher Brynner agreed to give a voice to the people of Sanctuary District A on Channel 90, saying although he'd lose his interface operating license, at least he would get great ratings. (DS9: "Past Tense, Part II")
In 2268, the Master of the Games on Name the Winner threatened to do a special on Flavius Maximus if he brought the network's ratings down. (TOS: "Bread and Circuses")