Active Directory™ is the directory service that provides the foundation for distributed networks built on Windows 2000 and later domain controllers. The Active Directory APIs provide access to the data stored in the directory.
Active Directory Service Interfaces (ADSI) is a set of COM interfaces used to access the capabilities of directory services from different network providers in a distributed computing environment, to present a single set of directory service interfaces for managing network resources. Administrators and developers can use ADSI services to enumerate and manage the resources in a directory service, no matter which network environment contains the resource.
ADSI makes it easier to perform common administrative tasks, such as adding new users, managing printers, and locating resources throughout the distributed computing environment.
The Microsoft Exchange Server directory can be accessed using ADSI interfaces. With the ADSI interfaces, you can use high-level tools such as Microsoft Visual Basic®, Java, C, or Microsoft Visual C++® to create directory-enabled applications. With ADSI you need not be concerned about underlying differences between various directory implementations or namespaces because, in the provider-based model that ADSI supports, ADSI can serve as the interface to a number of directory services, accessing each one through its own provider.
This means that you can build applications that use a single point of access to multiple directories in the network environment, whether those directories are based on the Lightweight Directory Access Protocol (LDAP), Novell Directory Services (NDS), or the Microsoft Windows NT® version 4.0 Security Account Manager (NTDS).
www-Sharp Active Directories viewer lets you examine ADSI structure, view ADSI components properties.