Windows Identity Foundation

Windows Identity Foundation (WIF) is a Microsoft software framework for building identity-aware applications. It provides APIs for building ASP.NET or WCF based security token services as well as tools for building claims-aware and federation capable applications.

Windows Identity Foundation is supported on IIS 6/Windows Server 2003, IIS 7/Windows Vista, Windows Server 2008 and Windows 7. Version 1.0 shipped as a standalone product, but the product is now included as a part of Microsoft .NET Framework v4.5.

WIF has the following major features:

The Microsoft documentation can mislead readers into thinking that WIF allows only the following types of claims-aware applications to be constructed: ASP.NET web applications and WCF service applications. This is not the case. Claims-aware Windows client applications can be built as well as any other type of custom claims-aware application. The misunderstanding arises from the fact that the security token service (STS) built using WIF can only be an ASP.NET application or WCF service application.

...
Wikipedia