What's a Podcast, You Ask?

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. 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. The term "podcast" is derived from Apple's portable music player, the iPod. However, known synonyms for the word pod are capsule, case, container, hull, husk, shell, and vessel. A pod is obviously a container of some sort and the idea of broadcasting to a container or pod correctly the describes the process of podcasting. More about the name itself can be found in the History of podcasting article.

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.

Source: wikipedia.org