RSS is Short for RDF Site Summary or Rich Site Summary.  An XML format for syndicating Web content.

A Web site that allows other sites to publish some of its content creates an RSS document and registers the document with an RSS publisher.  A user that can access RSS-distributed content can use the content on an alternate site.

Syndicated content includes such data as news feeds, event listings, news stories, headlines, project updates, excerpts from discussion forums, or even corporate information.

"RSS, The ultimate idea is that you should get the information you want when you want it"
 Bill Gates, Microsoft Corp. 20 May 2004