What are the Notifications in Windows 8?

There are three types of Notifications in Windows: Tile Notifications, Toast Notifications and Badges.

Tile Notifications display information which you can see directly on the tiles. Tiles which are able to display notifications are called Live Tiles. Live Tiles can be turned-off if you wish to by right-clicking the tile, and select Turn Live Tile Off from the App bar at the bottom of the Start screen.
 

Toast Notifications contain relevant information of the content of the apps and provides you quick access of the content itself. It’s a time-driven notification that can appear in your screen whether you are in another app, Start Screen, Lock Screen or even Desktop Screen. For example, if you are currently reading some emails using your Mail app and you have an appointment set in your calendar, a Toast Notification is displayed on top-right of your screen once it’s time to remind you.
 

Badges are summarized notifications displayed on the bottom-right corner of the tiles.