RSS (which stands for "Really Simple Syndication") is about getting live feeds of web content directly to your computer. RSS takes the latest news from different web sites that you've selected, and pushes it down to your computer for quick scanning.
If you are interested in a stream of information, you simply subscribe to that RSS feed. As updates are made to that stream, they are automatically delivered to your computer. The benefits increase exponentially as you subscribe to more feeds. Instead of individually checking different websites and documents, any changes to any feed you've subscribed to will automatically be delivered to your PC.
As an example, let's say you want to be notified when the Session Calendar is updated. You would subscribe to that feed, and configure your RSS reader software to alert you when new information is available. When the Session Calendar is updated, the new RSS will be picked up by your RSS reader and will notify you.