Apple didn’t invent the concept of podcasts, but they sure popularized them. They used to be called syndicated audio, and were pretty niche. Then Apple added it as a feature of iTunes. The idea was that because your iPod didn’t have any wifi or data connection, you couldn’t listen to new content while out and about. So you would plug your iPod into your computer with iTunes to sync down all the latest content before you leave for the day. Then they needed feeds of new content to provide to the users, so lots of new episodicals were started, and Apple grouped them under the umbrella of “podcasts”.