Short for "Really Simple Synication" (a.k.a. Rich Site Summary or RDF Site Summary), refers ti a group of XML based web-content distribution and republication (Web syndication) formats primarily used by news sites and weblogs (blogs). Any website can issue an RSS feed. By subscribing to an RSS feed, you are alerted to new additions to the feed since you last read it. In order to read RSS feeds, you must use a "feed reader," which formats the XML code into an easily readable format (feed readers are to XML and RSS feeds as web browsers are to HTML and web pages.

An RSS document (which is called a "feed", "web feed", or "channel") includes full or summarized text, plus metadata such as publishing dates and authorship. Web feeds benefit publishers by letting them syndicate content automatically. They benefit readers who want to subscribe to timely updates from favored websites or to aggregate feeds from many sites into one place. RSS feeds can be read using software called an "RSS reader", "feed reader", or "aggregator", which can be web-based or desktop-based.