Saving this five part series to come back to properly later:

Money is chasing money. Podcast advertising expanded at a 48 percent rate last year, and it’s forecast to grow about 25 percent a year through 2020. By that point, it would be approaching half a billion dollars in annual ad revenue. That growth is rising from a small base, yes, but it’s very reminiscent of the old Interactive Advertising Bureau charts of Internet advertising we saw at the turn-of-the-century: tiny numbers growing explosively.

http://www.niemanlab.org/2016/09/an-island-no-more-inside-the-business-of-the-podcasting-boom/