Below is a definition of podcasting pulled from Wikipedia that provides you with information about podcasting, its roots and some of the techincal aspects surrounding podcasting. The following is provided free from editing and I take no credit for this wonderful explanation.
Podcasting, created by former MTV VJ Adam Curry, is a term that was devised as a crisp way to describe the technology used to push audio content from websites down to consumers of that content, who typically listen to it on their iPod (hence the "pod") or other audio player that supports mp3 at their convenience. The term podcasting is meant to rhyme with broadcasting and is a derivative of the iPod platform. While not directly associated with Apples iPod device or iTunes music service, the company did contribute both the desire and the technology for this capability. Podcasting is not unlike time-shifted video software and devices like TiVo, which let you watch what you want when you want by recording and storing video, except that podcasting is used for audio and is currently free of charge. Note, however, that this technology can be used to push any kind of file, including software updates, pictures, and videos.
Podcasting uses an XML-based technology called RSS, or Really Simple Syndication. Content publishers describe new content in an XML RSS file which includes dates, titles, descriptions, and links to MP3 files. This auto-generated file is called an RSS feed. The key to making podcasting work with RSS is enclosures, a feature supported by RSS 2.0.
What makes podcasting special is that it allows individuals to publish (podcast) radioshows, that interested listeners can subscribe to. Before podcasting you could of course record a radio show and put it on your website, but now people can automatically receive new shows, without having to go to a specific site and download it from there.