Podcasting makes most of its money through ads, which last year generated revenue of just $1.3bn, according to Omdia, a data firm—equal to 6% or so of the recorded-music industry’s sales, or the box-office takings of one Hollywood blockbuster. Why the big noise about a small business?One reason is growth. Global podcast listeners will exceed 2bn by 2025, Omdia reckons, from 800m in 2019. Ad sales may nearly treble, to $3.5bn. As giants hoover up shows, advertisers put off by fragmentation can buy many spots in one place.Second, podcasts give audio-streamers a chance to own content, which they cannot do with music. Most of the world’s tunes are owned by three record labels, which skim off about 70% of the streamers’ revenues. No matter how much they grow, firms like Spotify find their costs grow with them. The fixed cost of acquiring a podcast means that growth can boost margins.Last, the ability to own podcasts gives streaming services a way to differentiate themselves. Unlike video-streamers, which compete on content, Spotify, Amazon and Apple offer roughly the same library of 40m songs. Artists, who see streaming mainly as a way to promote their more profitable live shows, have little incentive to be exclusive to one service. Original podcasts are a way to lure fans.www.pwtbroadcasting.com