(Rich Site Summary, Really Simple Syndication)
RSS is the technology that enables easy tracking of web content from the chosen source in an XML file called an "RSS feed". The User uses a special software called an RSS reader, tracker, or aggregator to get new information from the source.
1) User with tracker registers the source.
2) The tracker periodically (using user defined period) checks for new information. This action is usually done automatically.
3) The new information is displayed in the tracker
RSS is used in blogs and e-news servers like BBC but currently it has widespread use.
For example here is the feed for the latest devices on forum.nokia.com: