Increasingly, communication is created and distributed in a computer-readable digital form. This change means that the same basic technologies can be used to transmit all forms of communication-text, audio,or video- in an integrated communication system such as the internet. Thus, separated channels of communication are no longer needed for each medium. The mass media, telecommunications, internet, and computer software industries are all part of the same information sector of the economy-they are,in other words, converging. Laws and public policies governing the media, career opportunities in communications industries, social and personal issues arising form media consumption, and even theories of the media and their role in society are all changing. In 1741, the first US magazine appeared. During the American Revolution,many magazines took a more politics lone, few Magazines were popular or long-lived during this times. They covered weekly events,politics, and art and contained reviews, travelogues, short stories, and fiction; they were aimed at an educated elite. By the 1820s magazines of more general interest, such as the Saturday Evening Post, began to appear, The number of magazines increased during the Civil war,and they began to reach wider audiences. The Postal Act of 1879 made distribution cheaper. The most popular genres int he 1920s were probably big band music, jazz, country, blues, classical, broadway tunes, and gospel. Form those evolved rhythm and blues, soul, and rock and roll, which have fragmented and further evolved into contemporary genres like hip hop, rap, metal, modern rock, alternative, and so on. Music companies decide which albums and songs to promote through radio, billboards, newspaper and magazine ads, music videos, music video services like YouTube, and online services like rhapsody. The record companies distribute recording in a variety of ways, including rack jobbers, retail music stores, big-cain stores, internet stores or catalogs, record clubs, download services like iTunes, and streaming services like Spotify. The big three are Song, Universal, and Warner, which have over 80 percent of the US market. The main radio networks were put together by David Sarnoff at RCA/NBC and William Paley at CBS, who saw potential to make and sell radios, as well as to sell advertising. during their high point, network radio relied largely on music but also carried news, sports, comedy, variety shows, soap operas, dramas, suspense, and action adventures. Many of those genres moved to television after 1948. After television converge and audiences began to grow, around 1948, network radio also began to lose much of its audience to television. Some of the types of entertainment it had relied on worked better for the mass audience with a visual component on television. Radio came to rely more on music, which could be programmed locally by DJs playing records.