Really simple syndication
RSS is the most commonly used XML feed format. This is a simple machine-readable file that is used in blogs and websites to keep users and customers updated with new information, such as new posts or site updates. Because the RSS standard is so popular, there are many blog reader programs available that can aggregate news from many different sources and present the user all this information in one place.
See also Atom, a newer type of feed designed to supersede RSS.