A podcast is an audio which has been given a special xml link.
The great thing about podcasts rather than audio is the fact that people can download your audio mp3 file and listen to it whenever they want to using their ipod, PDA, computer or other device.
The other great thing about podcasts is the fact that people can subscribe to them using an RSS link which is shown as an orange button. A subscriber clicks on that link and all your podcasts are automatically downloaded, which means they do not have to keep returning to your site to download your latest podcast.
It also makes your job as the podcaster easier because you only need to put your link into a podcast directory once and every time you update your podcast link (or feed as it is known) it will automatically be updated in the podcast directory. So once you go through the work of submitting your feed once you never have to do it again.
Have you tried podcasting? How has it been?