What is RSS?
RSS, which stands for Really Simple Syndication or Rich Site Summary, is an information format. Using XML the information in this blog, or the New York Times, is formatted in such a way that a computer program can read the information. (However, like email, you don't have to know how it works in order to take advantage of it.)
If you have a News Aggregator, like Bloglines, NewsGator, My Yahoo!, or the Firefox web browser Live Bookmarks you can receive updates from the sources you choose. You get updates on a regular basis, usually every hour or so, and you only get them from the sources that you subscribe to. Unlike an email subscription, there is no way for someone to get your "address" and send you stuff you don't want. (However, it is possible for a RSS feed producer to insert ads into the feed. It's sort of like the little ads at the bottom of emails from many free email services, except usually with pictures.)
Using a news aggregator is a time saver. Instead of you coming to this blog, CNN, the Distant Librarian, Library Stuff, and/or whatever other sources you check regularly, the news aggregator visits them for you. It's kind of like a personal shopper. You tell it what you want it to go get, and it gets it for you. Most people report 50-75% reductions in the amount of time they spend checking the sites they regularly visit. It's especially good for sites, like this one, where the authors don't post every day. Instead of checking my site to see if I've posted, the aggregator does it for you. Also, in many services you can choose to receive only the headlines or titles of the articles/posts, so you can easily skim through and only read the stories which really interest you.
I hope this helps you get more out of the web!
For more information try:
Non-technical explanations: http://www.faganfinder.com/search/rss.shtml; http://rss.softwaregarden.com/aboutrss.html
RSS for educators: http://www.weblogg-ed.com/rss_for_ed
RSS for librarians: http://www.llrx.com/features/rssforlibrarians.htm; http://lii.org/search/file/liirss/
Technical info: http://www.xml.com/pub/a/2002/12/18/dive-into-xml.html; http://en.wikipedia.org/wiki/RSS_(protocol)