I never even knew that these functions existed in Google Reader. Straight from Google Operating System...
Web applications track many user actions and use them for different purposes: improving the products, finding patterns, building user profiles etc. For example, Google Reader records some of your actions without providing options in the interface to access the data. Here are some addresses where you can find historical data about the items you've subscribed to (click on "View all items" to see all the posts).
* All the posts you've emailed to your contacts:
* All the posts you have marked as unread at some point (to keep a post unread, you need to uncheck "Mark as read" from the options bar; note that "Mark all as unread" will not maintain this state):
* All the posts you have marked as unread and are still unread (Google Reader calls them "saved items"):
* Did you click on a post's main link to go to the original location? You'll find it here:
* Did you click on a link from a post's content? The post should be included in this list:
* If you use the list view, you can find the list of posts you've actually read (or at least you have clicked on the title):
* Are Google's recommended feeds interesting? Check the list of recommended feeds you've subscribed to:
* Did you accidentally dismiss a recommended feed? You'll find it here: