This is a link to your notifications, 
a number will be displayed if there are any unread.
This is a link to your messages, 
a number will be displayed it there are any unread.
This is a link to your bookmarks, 
clicking on it will add the current page to your list and highlight the icon.
This is a discussion thread which may or may not have replies.
This is a question which does not have any suggested or confirmed answers as replies.
This is a question which has at least one suggested answer as a reply. Hover over the icon to preview the post.
This is a question which has at least one confirmed answer. Hover over the icon to preview the post.
The gear icon serves as a link to application options, including subscription.