This is a really nice chart from The Economist, Dec 8, 2012. It nicely shows the overarching life cycles of major media concepts.
We can speak of a media industry from the end of the 18th century when print slowly became a mass market. Media was dominated by newspapers for a long time (although it took time for the modern newspaper to emerge) and advertising represented increasingly large revenues. The newspaper has been challenged by the concept of "broadcasting" in the 1920s starting with the radio industry. Television, of course emerged as the ultimate broadcasting medium after WWII, in fact launched by the dominant radio broadcaster RCA. From 1950 to the end of the century TV broadcasting takes over the newspaper (and advertising with it). In the last couple of years Cable TV drives growth but the concept of a broadcast medium is maintained. All this changes at the start of the new millennium with the birth of "mass interactivity" over the Internet. It starts with computers and websites and now mobile but we are really talking about the same thing. And my bet is that broadcasting will fold naturally into mass-interactivity where we'll reach major TV channels through the Internet on demand.