LDAP and ADSI
Microsoft provides the Active Directory Service Interfaces (ADSI) for developing client-side directory service applications. ADSI consists of a directory service model and a set of COM interfaces. These interfaces enable development of network directory service access applications for computers running on Windows 2000 Professional, Windows NT Workstation, Windows 98 or Windows 95. ADSI uses an LDAP provider to communicate with Active Directory. ADSI can also access Novell NetWare Directory Services. ADSI can communicate with various directory services by using their native providers.
For more information about ADSI, see Active Directory Service Interfaces.