.NET Passport is Microsoft’s solution for federated identity management. It offers single sign-on (SSO) to multiple web-based service providers, while protecting a user’s privacy in e-commerce transactions.
This program by Microsoft maintains identification and authentication services for people who register to their Passport program on the web. Registration allows the customer to use one ID (an e-mail address) and password at multiple Internet e-commerce sites with vendors who participate in the program.
With this program, Microsoft acts as the trusted identity provider, vouching for the identity of the people who have registered to the service providers, the companies that participate.