A Podcast RSS feed is what allows the entire system to function. To begin at the beginning, a podcast is a regular distribution of audio or visual files, called episodes, to a users podcast client. The people who use a podcast are called subscribers, and the podcast client is what allows them to subscribe to a feed. The podcast client is a program that connects to the internet, looking for a specific file the user has subscribed to, or told it to look for. That file is an RSS feed, a machine readable piece of coding that sends information back to the podcast client. RSS feeds can be used to distribute many kinds of information, and were originally used for blogging and distributing blog posts to subscribers. As time went on, however, a few people had the idea of enclosing information about media files within the RSS feed so that software could be written to find that information and download the files described.
The Podcast RSS feeds became a hit, and podcast clients were quickly written to allow people to use the new encoding. Podcasting became a means of quickly and cheaply sharing episodes with subscribers. Rather than requiring subscribers to visit the site that hosted the files everytime they wanted to know if a new episode was released, users could rely on the podcast client to do the work for them, keeping track of numerous podcast rss feeds that interested them and downloading the files to be viewed when they wished.
Podcast RSS feeds are now used to distribute a number of different types of podcasts. Some producers use it as way to share a comedy or news program that they produce, others podcast in order to share music files they create, and some podcast to share video files they have created and to showcase their work. Podcasting allows the producers to become radio or television stars without the large investment in time and money that wuld be required to do that. Because podcasting has such a low entry cost, requiring little more than a server and a domain to host the site and a way to record the media, thousands of people who otherwise would not have a chance to work in a media environment have a chance to do so through their podcast rss feeds.
In this way, podcast RSS feeds allow media publishing over the internet at a fraction of the cost of other forms of media distribution, permitting people with much smaller budgets to compete in some way. However, podcast rss feeds are also attracting more established companies and groups as well, bringing people from NPR radio stations and news organizations like CNN who use podcasting as yet another means to distribute their product to end users.