A podcast can be several things. In its broadest sense, a podcast is digital media that you can listen to or see whenever you want. Unlike a broadcast, which you have to watch or hear when it "airs," a podcast can be very portable. You can experience it whenever and where ever you want--place and time shifted would be the geeky way to talk about it. :o)
In its simplest form, a podcast is an audio file on the internet. You can listen to it on your computer. You can download and save it to your mp3 player. Once it is on your mp3 player, you can listen to it whenever you want. The most popular mp3 player on the market today is the iPod.
Podcasts can also be video files. Just like the audio podcast, these can be viewed in your browser on your computer. They can also be downloaded to a video iPod or other supported player.
Perhaps the most powerful aspect of the podcast technology is that it can be combined with RSS. As a teacher, you could have a podcast series for your class. Using RSS, anyone in the world could subscribe to your podcast series. Once a user subscribes, every time you publish a new episode to your podcast series, everyone who subscribed to it automatically gets a copy downloaded to his/her computer. If they use an RSS aggregator like iTunes, the next time the user plugs in his/her iPod, the podcast is downloaded to the iPod.
Podcasts are much easier to create than most people realize. In fact, the most complicated part of making a podcast is creating quality content, not the technical aspects of making the podcast!
The iTunes store has many, many podcasts for education. You can browse them K-12 and higher education. You can also search for specific content keywords.
Wikipedia Link: Podcast
Related Wikipedia Links:
Dictionary.com Link: Podcast
