What is RSS?
RSS, or Really Simple Syndication, is a technology that delivers Web-based headlines, blurbs, and article links from a wide variety of sources directly to you through an RSS reader (like FeedDemon or NewsGator) or customizable websites (like MyYahoo.com or Bloglines.com). RSS brings content to the user instead of asking the user to come to the content, allowing users to stay on top of updates from multiple web sources in one, convenient place.
Resources:
Feed 101 – Google Support
RSS – Wikipedia
What Is RSS – XML.com