RSS is a simple technology for syndicating content around the web, to many users automatically. RSS stands for Rich Site Summary, although it’s more commonly expanded as Really Simple Syndication. It’s a way for websites to easily broadcast updates and for users to see all of the updates from multiple sites in one location, without having to visit each individually.
The actual RSS file is an XML document with a specific, standardized format. The document shows a list of content items from a website, or a section of a website, and is automatically updated with any newly-added content.
In order to see these updates, a web user needs an RSS reader. These can be stand-alone applications or web-based, and can incorporate different features, but the basic function is to save the RSS feeds a user designates, show all the content items listed in the RSS feed and then check those RSS feeds regularly for new content.
RSS is most often thought of as a way to aggregate text content such as blog posts. However, it also powers most Podcast directories. The iTunes podcast directory is essentially an RSS reader that checks a feed (Podcast) for new items (Podcast episodes).