Originally posted on: http://geekswithblogs.net/tmurphy/archive/2013/07/03/building-apps-that-work-together.aspx

Writing apps that stand alone will only get yon so far.  If your app can allow the user to leverage other applications and share data you Can have a real winner on your hands.

Jake Sabulsky started off by explaining that you should be concentrating on the core functionality of your app and letting the framework take care of the features that users require these days.  This is implemented be leveraging contracts.  When Windows 8 was released it included the File, Share and Pickers contracts.  With the release of Windows 8.1 they have added the Contacts and Calendar contracts.

There have been a number of improvements to the original contracts. The File URI contract will now automatically detect the size that a new windows should be opened and will also allow you to programmatically influence new window size.  The Share contract has been enhanced by allowing apps to always share screenshots and links to the app in the store.

To my thinking the contracts are one of the most powerful features of Windows 8.  Take the time view this session and learn how to leverage them.