RSS (really simple syndication) is a way to monitor different sources of web content without having to go to every web page which might have new content items that are of interest to you.

Instead, you use an RSS aggregator or RSS reader to subscribe to RSS "feeds". Either on an interval or when you ask it, the aggregator goes out and gets the title and a brief blurb about all of the new articles published by your subscribed feeds since the last time your reader checked.

That way, it's one stop shopping for you. If there is an article that looks interesting, you can select it and a browser window will load that page for you.

If you use a web-based aggregator service, then you might have a limit on the number of feeds that you can subscribe to at a time.

If you use a desktop RSS reader, you can usually subscribe to as many feeds as you want.

Web hosted aggregators:
Google Reader
News Gator
and many more....

Desktop Software:
Click here for a list of RSS Readers available