RSS The acronym was previously known to mean Rich Site Summary and was developed by Netscape.
It now generally refers to RDF Site Summary or more recently, Really Simple Syndication, an updated and XML-compliant version of the Netscape technology. RSS is an XML-document format intended to describe, summarise, and distribute the contents of a website as a 'channel', made available for access via an RSS reader.
If you are looking for RSS reader software, search for SharpReader [Windows] Wildgrape NewsDesk [Windows], FeedReader [Windows], NetNewswire [Mac OS X], Plucky [Mac OS 9], Beaver [Windows, Mac, Linux] or many others through the web. Most are quite small and fast to download.