RSS stands for Real Simple Syndication. It's a simple way for web sites to package their content so that you can read it on your own computer without actually having to go to each site.
If you go to several web sites several times each day checking for new content, RSS is exactly what you need. With an RSS reader, the new content comes to you instead of you having to go to it.
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RSS readers are also called aggregators. A brief search of the Internet will turn up thousands, but these are some of the best:
Sites across the web—big and small—publish RSS feeds. Look for the icon or "RSS feed" link on your favorite sites to subscribe to their feeds.
Here are a few to get you started!