A few months before its eighth birthday–on July 7, 2013–Google will be shutting off its Google Reader service. Reader, for those who don’t use it, aggregates RSS feeds.
RSS stands for Really Simple Syndication. Websites use it to announce when they have a new post and users can then subscribe to those announcements (called RSS feeds) to be constantly updated. If you sign up for email announcements for a blog you like, for example, you get constantly notified. Maybe even annoyingly so. But with RSS, you can sign up and get the update when you want (or still have the notification announce itself). They run behind a lot of websites too. Almost every podcast uses RSS to deliver their new episodes.