The term podcast derives its name from Apple's iPod, but to create, publish and listen to a podcast you don't need to own a iPod, or any other portable music player for that matter.
In a nutshell, Podcasting is a new type of online media delivery. You can publish selected audio/video files via the internet and allow your users to subscribe via an RSS feed to automatically receive new files. Podcasting lets you create your own syndicated online radio program, with the content of your choosing. The host or author of a podcast is often called a podcaster.