What are live tiles ?
Windows 8 live tiles is a feature for Modern UI apps that uses the internet to bring live updates to users of Windows 8.
Why live tiles ?
Live tiles exist on the Windows 8 start screen, and are useful for having instantaneous information on constantly changing data like stock indexes, international weather, as well as local and international news as they request the notifications without opening the application.
How does the tile change ?!
The tile is updated when the application sends a TileNotification followed by updating the tile via TileUpdateManager.
How can we use the Live Tiles ?!
By adding the text and the image you want to be on the tile to the solution.
By adding images through the internet and your text on the tile.
Via NotificationChannelManager by getting the data from the service URI
To use the Live Tiles Notifications without a Web Service is easier as you put your content directly by referencing them and passing them to the update function but using a Web service is much more time saving as to be used in other applications and scales down the size of the app.
Where to begin ?
Use the NotificationsExtensions Library which is a premade library with Tile objects pre-defined to help developers you can find it in the Windows SDK Sample which illustrates the whole theory of the live tiles.