Active Directory (or AD) is Microsoft’s trademarked directory service developed for Windows domain networks. It is included in most Windows Server operating systems, and was an integral part of the Windows 2000 architecture. With the release of Windows Server 2008, however, Active Directory became an umbrella term for a broad range of directory-based identity-related services.
Active Directory was designed specifically for distributed networking environments. Its purpose is to serve as a centralized and standardized system that automates the network’s management of user data, security, and distributed resources, as well as enable interoperation with other directories. As a result, Active Directory will store information about sites, systems, users, shares, and any other network object for use by all enterprise resources for authentication, rights management, and other applications.