Podcasting is similar in nature to RSS, which allows subscribers to subscribe to a set of feeds to view syndicated Web site content. With podcasting however, you have a set of subscriptions that are checked regularly for updates and instead of reading the feeds on your computer screen, you listen to the new content on on your iPod (or like device).
The format used for podcasting is RSS 2.0 with enclosures. The podcasting enclosures refer to all binary (non-text) downloads. You can read the text description of the enclosure before downloading the item to view.