RSS (Rich Site Summary) is a format for delivering regularly changing web content.  Many news sites, blogs and other online publishers syndicate their content as an RSS Feed to whoever wants it.

 

RSS allows you to get the latest content from the sites you are interested in. You don't have to visit each site individually and you don't have to join each site's email newsletter.

 

Feed Reader or News Aggregator software collects the RSS feeds from various sites and displays them for you to read and use.  

 

Popular feed readers include Amphetadesk (Windows, Linux, Mac), FeedReader (Windows), and NewsGator (Windows - integrates with Outlook). There are also web-based feed readers available.  My Yahoo, Bloglines, and Google Reader are popular web-based feed readers.  There are many more.

Once you have your Feed Reader, it is a matter of finding sites you are interested in keeping up to date with, and adding their RSS feed to the list of feeds your Feed Reader checks.  Many sites display a small icon with the acronyms RSS, XML, or RDF to let you know a feed is available - like this one does (look in the right hand sidebar for an orange symbol).

 

Your Feed Reader will have somewhere where you can enter the URL for the feed you want to subscribe to - once you've done that, then any updates to that feed will appear in your Feed Reader for you to read at your leisure.