Active Directory Service Interfaces (ADSI) enable system administrators and developers of scripts or applications to easily query for and manipulate directory service objects.
ADSI present a single set of directory service interfaces for managing network resources from different directory services. Administrators and developers can use ADSI to manage the resources in a directory service, regardless of which network environment contains the resource. ADSI enables administrators to automate common tasks such as adding users and groups, managing printers, and setting permissions on network resources.
Applications written to ADSI will work with any directory service that offers an ADSI provider. For example, with ADSI, applications can access LDAP, NDS, the Active Directory service, and other directories with ADSI interfaces as long as the appropriate service providers are available.
The standard ADSI providers are found within multiple namespaces — typically directory services for various network operating systems. Providers enable communication between the server or client. ADSI includes providers for:
Source : microsoft.com website