What is a Contract in a Windows Store App

Windows Store apps use contracts and extensions to declare the interactions that they support with other apps. These apps must include required declarations in the package manifest and call required Windows Runtime APIs to communicate with Windows and other contract participants.

Contracts A contract is like an agreement between one or more apps. Contracts define the requirements that apps must meet to participate in these unique Windows interactions.

For example, Windows lets users share content from one app to another. The app that shares content out supports a source contract by meeting specific requirements, while the app that receives the shared content supports a target contract by meeting a different set of requirements. Neither app needs to know anything about the other. Every app that participates in the sharing contract can be confident that the sharing workflow is completely supported, end-to-end, by Windows.