The Subtitle tag was used in older versions of Apple Podcasts to provide a quick 255 character summary of your podcast underneath the title on it’s information page in iTunes. This can be a clever phrase or a continuation of the theme defined in your name. In the case of podcasts with names longer than 255 characters, this might be a good place to extend your name so that iTunes doesn’t inadvertently cut it off. This doesn’t seem like a particularly useful tag on the surface, but it’s part of the retro-fit Apple made to conform podcasting to the layout of the old iTunes Music Store. This tag was used in two places in your feed, with two different uses. It appeared in the channel definition as a subtitle for the podcast and it appeared in the item definition and is used for the Description of individual episodes in Apple Podcasts.
The Subtitle tag looked like this:
<itunes:subtitle>Subtitle of Your Podcast</itunes:subtitle>
Apple now relies on the RSS description tag to serve this same purpose.
