RSS is essentially a way to subscribe to content from a website meaning that you don’t have to visit the site constantly to look for updates. You can receive alerts when new content arrives on the website in question. In the case of the Optometry Blog, you will receive notification of when new Blog articles have been posted, CET articles have been uploaded and are available for consumption and news on upcoming events.
If you have never subscribed to an RSS feed then FeedBurner has a simple explanation of RSS and a list of Readers (Right Hand Column) We like to use Google Reader.