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 your site.
Originated by UserLand in 1997 and subsequently used by Netscape to fill channels for Netcenter, RSS has evolved into a popular means of sharing content between sites (including the BBC, CNET, CNN, Disney etc).
RSS solves myriad problems webmasters commonly face, such as increasing traffic, and gathering and distributing news. RSS can also be the basis for additional content distribution services.