Action Center is a new feature of Windows 10. It maintains notifications from Desktop apps, system notifications, and Universal apps. If you miss a notification, it is queued up in the Action Center. Also, in the Action Center you will find useful buttons called Quick Actions for fast access to useful system functions. The Action Center pane closes automatically when you click another window, Desktop or anywhere else, that is, when it loses focus. You can change this behavior with a simple Registry tweak.