RSS (Really Simple Syndication or Rich Site Summary) is a format for delivering regularly changing web content. Many news-related sites, weblogs (blogs) and other online publishers syndicate their content as an RSS Feed to whoever wants it. RSS is about “what’s new” or at least what’s new in terms of what people are currently writing about. It might be a new article on an old topic. Contrast this with the idea of querying a database on the Web to get specific information that may or may not be “new”. This would be an example of a web service.
Wikipedia reports the following:
An RSS document (called “feed”, “web feed”, or “channel”) includes full or summarized text, and metadata, like publishing date and author’s name.
A standard XML file format ensures compatibility with many different machines/programs. RSS feeds also benefit users who want to receive timely updates from favourite websites or to aggregate data from many sites.
Subscribing to a website RSS removes the need for the user to manually check the website for new content. Instead, their browser constantly monitors the site and informs the user of any updates. The browser can also be commanded to automatically download the new data for the user.