System.DirectoryServices namespace in .NET Framework Class Library
The System.DirectoryServices namespace provides easy access to Active Directory from managed code. The namespace contains two component classes, DirectoryEntry and DirectorySearcher, which use the Active Directory Services Interfaces (ADSI) technology. ADSI is the set of interfaces that Microsoft provides as a flexible tool for working with a variety of network providers. ADSI gives the administrator the ability to locate and manage resources on a network with relative ease, regardless of the network's size.
The classes in this namespace can be used with any of the Active Directory service providers. The current providers are: Internet Information Services (IIS), Lightweight Directory Access Protocol (LDAP), Novell NetWare Directory Service (NDS), and WinNT.