The similarly worded definition from The Associated Press Stylebook:
An abbreviation for Really Simple Syndication. A protocol for subscribing and distributing feeds that notify people of new entries on news sites, blogs, podcasts or other online information sources. Also RSS feed.And from Wikipedia:
RSS (most commonly translated as "Really Simple Syndication" but sometimes "Rich Site Summary") is a family of web feed formats used to publish frequently updated works—such as blog entries, news headlines, audio, and video—in a standardized format.What does that mean for you? It means timely updates from your favorite sources without having to visit a site's address. (It's like getting an e-mail when your site updates.) To take advantage you need a news aggregator (see here) or feed reader. I use Google Reader, but there are a variety of options available to you!
RSS Wikipedia article
What Is RSS?
RSS feeds: A primer, Unclutterer