Television (TV) news is considered by many to be the most influential medium for journalis. For most of the American public, local news and national TVnewscasts are the primary news sources.Not only the numbers of audience viewers, but the effect on each viewer is considered more persuasive, as described by Marshall McLuhan ("the medium is the message" in his book Understanding Media). Television is dominated by attractive visuals (including beauty, action, and shock), with short sound bites and fast "cuts" (changes of camera angle). Television journalism viewing numbers have become fragmented, with the 24-hour United States cable news television channels such as Cable News Network (CNN) starting in 1980, Fox News Channel and MSNBC in the 1990s. The industry divides television into local (List of television stations in North America by media market) in North America by media markets. Such television markets are defined by viewing area and are ranked by the number of audience viewers. New broadcast journalists generally start in the smaller markets with fewer viewers and move up to larger television stations and television networks after gaining experience. The larger stations usually have more resources and better pay.