The original inventors of radio, from Guglielmo Marconi's time on, expected it to be used for one-on-one wireless communication tasks where telephones and telegraphs could not be used because of the problems involved in stringing copper wires from one point to another, such as in ship-to-shore communications. Those inventors had no expectations whatever that radio would become a major mass media entertainment and information medium earning many millions of dollars in revenues annually through radio advertising commercials or sponsorship. These latter uses were brought about after 1920 by business entrepreneurs such as David Sarnoff, who created the National Broadcasting Company (NBC), and William S. Paley, who built Columbia Broadcasting System (CBS). These broadcasting (as opposed to narrowcasting) business organizations began to be called network affiliates, because they consisted of loose chains of individual stations located in various cities, all transmitting the standard overall-system supplied fare, often at synchronized agreed-upon times. Some of these radio network stations were owned and operated by the networks, while others were independent radio owned by entrepreneurs allied with the respective networks. By selling blocks of time to advertisers, the medium was able to quickly become profitable and offer its products to listeners for free, provided they invested in a radio receiver set.