RSS is a format for syndicating news and the content of news-like sites.
But it's not just for news. Pretty much anything that can be broken down into discrete items can be syndicated via RSS: the "recent changes" page of a wiki, a changelog of CVS checkins, even the revision history of a book. Once information about each item is in RSS format, an RSS-aware program can check the feed for changes and react to the changes in an appropriate way.

for the rest of this article visit here:http://www.xml.com/pub/a/2002/12/18/dive-into-xml.html

you can also check out this:http://www.daniweb.com/techtalkforums/thread37148.html
one of the poster gave explanation about it