Windows Live ID SDK
The Windows Live™ ID service (formerly known as the Passport Network) is the identity and authentication system provided by Windows Live. More than 380 million users have credentials that work with Windows Live ID.
You can use this powerful technology and enormous user base in your client applications and on your Web sites. The following resources tell you how.
The Windows Live ID Delegated Authentication SDK for Application Providers helps you get permission to access users' information on Windows Live services. Then you can deliver great new functionality to users while they remain in firm control of their data.
The Windows Live ID Web Authentication SDK provides a platform-independent interface and plenty of samples to help you use the Windows Live ID service to verify the identity of visitors to your Web site.