Really Simple Syndication (RSS) is a lightweight XML format designed for sharing headlines and other web content. Think of it as a distributable "What's New" for a web site or page. (webreference.com)

A news feed reader can check RSS-enabled web pages on behalf of a user and display updated articles. RSS saves users from having to repeatedly visit favorite web sites to check for new content or be notified of updates via e-mail. It is now very common to find RSS feeds on most major web sites, as well as many smaller ones. (Wikipedia.org)