People have been uploading audio and video files to the web for years, but with Podcasting the media files are more accessible because when your content is updated, subscribers can get it faster and right away. Receiving a podcast is like subscribing to a magazine.
The definition on Wikipedia is:
A podcast is a media file that is distributed by subscription (paid or unpaid) over the Internet using syndication feeds, for playback on mobile devices and personal computers[1]. Like 'radio', it can mean both the content and the method of syndication. The latter may also be termed podcasting. The host or author of a podcast is often called a podcaster.
Though podcasters' web sites may also offer direct download or streaming of their content, a podcast is distinguished from other digital audio formats by its ability to be downloaded automatically using software capable of reading feed formats such as RSS or Atom.
This icon has been approved to signify
an RSS feed.