what is a Podcast?
A podcast is a digital media file, or a series of such files (pdf, audio or video) that is distributed over the Internet using syndication feeds for playback on portable media players and personal computers.
How to subscribe to a Podcast using itunes?
1 – Download the program itunes press here. ( If is not installed in your computer). If you already have it installed in your computer go to the next step.
2 - Open the program itunes. Press where it says itunes Store next to your left hand.
3 - Writes a word related to the subject that you’re looking for in the corner of your right hand of your screen where it says (Search itunes Store). Press Enter.
4 - Press where it says PODCASTS.
5 - Press SUBSCRIBE.
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.
 Definition of podcast thanks to: Wikipedia