Windows 10 devices are now configured to automatically download and apply all Windows 10 updates that have been tested and approved by Technology Support. Most updates will run silently with no user notification necessary.
In the event an update requires a reboot you will receive several notifications relating to the update:
First you will see a "Windows Toast" style pop up in the bottom right which will hide to the notification area after a few moments:
The second Windows 10 notification will pop up letting you know of a pending required restart. You can choose to restart immediately, or delay restarting for up to 4 hours. When the Snooze time has less than 30 minutes remaining before reboot, this window will pop up again and will not be able to be closed: