Directory services are an important though rarely mastered component of enterprise application development. There has always been some support for directories in the .NET Framework, but the .NET Framework 3.5 provides a new AccountManagement namespace designed specifically for managing security principals...

Active Directory Federation Services (ADFS) was introduced in Windows Server 2003 for organizations that need to participate in standards-based identity federation. With ADFS, you can more easily validate identity data from other organizations, leading to greater interoperability with your partners....