Appointments and Contacts
Interaction with the built-in applications in Windows Phone is achieved through the Launcher and Chooser APIs. These APIs are contained in the Microsoft.Phone.Tasks namespace and expose their functionality through tasks that provide a consistent and seamless experience for your application users.
As the name implies, a Launcher task launches one of the built-in applications such as the e-mail client or web browser to allow the user to complete some task. Composing an e-mail, sharing something on a social network such as Twitter, or opening the browser to a specific web site are common examples of Launcher tasks. ...