RSS is a technology that is being used by millions of web users around the world to keep track of their favorite websites. In the old days of the web to keep track of updates on a website you had to bookmark websites in your browser and manually return to them on a regular basis to see what had been added. RSS stands for Really Simple Syndication.
Many people describe it as a news feed that you subscribe to. I find the subscription description helpful. Its like subscribing to a magazine that is delivered to you periodically but instead of it coming in your physical mail box each week when the news is published it is delivered to your RSS Reader every time your favorite website updates.