RSS stands for Rich Site Summary and is used to deliver content to end users. It is ideal for websites where information constantly changes (like a news site). What is convenient about it is that you don't need to visit each site individually and search for new updates. Instead, you can subscribe to an RSS feed and the content will be delivered to you either in your email program (like Mail) or in your web browser (like Safari). For instance, I have subscribed to Rolling Stone Magazine's RSS feed. Now, instead of going to rollingstone.com and searching through the site, getting bombarded by advertisements and offers, I can simply check the RSS feed in my email program and all of the most recent updates come in almost like email. It also strips away formatting and navigation so that each new article is very simply and quickly displayed. This is also ideal for mobile devices with limited internet connectivity. The content can be delivered very fast and efficiently. It is very convenient.
So if you're interested in checking it out, click the link in the upper-right that says "Subscribe to RSS feed" and if you're using Safari, you'll notice that you can now view the blog entries in a very simple format. You can bookmark this link OR you can add it to your Feeds section in your Mail program. There are also separate applications that will organize your RSS feeds as well.