Podcasts emerged from a niche audience in 2005, when the iPhone announced that it would support the medium, to now having 73 monthly listeners in the US according to Edison Research.

Technology and consumption shifts have enabled this rise in popularity, as consumers are increasingly shifting towards more easily digestible means of learning, from the decline of long-form news and even book readership.

This trend towards listening rather than reading follows the decrease of literacy among Americans, of whom as few as 43.1% of adults read a book in 2015, according to the National Endowment for the Arts, with the percentage even smaller in younger age groups.

Corporations have jumped on this trend, including Amazon, which launched an Audiobook app called Audible. Simultaneously, more specific informative podcasts have also become more popular, from Freakonomics Radio, an economics show, to Revisionist History, which delves into specific and under-discussed parts of history, often running 20 minutes or longer discussing these topics, much like and on-demand version of old radio shows.

The continued growth and success of Podcasts has opened up a new market for advertising, tying the medium to the complex world of sponsorships. Advertising firms have arrived specifically tailored for podcasts, such as ad firm Midroll Media.

“When you look at the top 500 or 1,000 podcasts, there are now hundreds of shows with hundreds of thousands of listeners each that are making sustainable amount of revenue in the half a million to million dollar range, which is a significant jump from a few years ago,” said Erik Diehn, chief executive of Midroll Media.

The realm of podcasts is young; creators are still experimenting with the form, from the style of content they produce, expanding away from the standard radio show format, while testing new monetization models such as subscriptions.