Notifications
Clicking the notifications icon (which looks like a satellite) in the header bar brings down a drop-down list showing the five most recent notifications. If you have unread notifications, this will appear as a number in red over the icon.
Notifications tend to take the form “Person A has commented on Person B’s post,” “Person A started sharing with you,” or “Person A has mentioned you in a post.” From this drop-down, you can:
Click the person’s name to view their profile page.
Click post to view that post.
Click Mark all as read.
Click View all to go to the Notifications page.
The notifications page shows you all previous notifications made to you, 25 to a page.