Most television networks earn money by airing advertisements during their programming. Other stations, such as PBS, generate revenue through private donations and government funding. Cable and satellite providers, on the other hand, earn money by charging their subscribers monthly service fees.
Advertising is the backbone of television funding. Companies are often willing to spend hundreds of thousands of dollars for a 30-second advertising slot on a widely watched program. The values of advertising slots are determined primarily by the number of viewers in each age demographic. Advertisers deem the 18 to 49 demographic as the most valuable because they perceive them to be most impressionable, according to Brian Dakss for CBS News.