What is it?!

Really Simple Syndication (RSS)
RSS is an XML based format used for content distribution and syndication. Subscribing to RSS Feeds allows you to receive custom, up-to-date information from your favorite online content sources without having to regularly check the site for updates. Installing a news reader that displays RSS feeds from the websites you specify allows you to keep up to date with all your favorite content by checking the RSS feeds you have subscribed to and displaying new items from each feed. Instead of downloading a dedicated news reader, you can also use a web-based news reader.