Active Directory (AD) is a directory service created by Microsoft. Microsoft Windows Server 2000, 2003, and 2008 Active directory AD , Certificate services CS , Active directory Migration, Active Directory Rights Management Services(AD RMS), Active Directory Lightweight Directory Services (AD LDS), Active Directory Federation Services (AD FS), Lightweight Directory Services‎, Active Directory Domain Services (AD DS, ADSI, DHCP, DNS, Virtulization- Microsoft Hyper-v, Vmware, Citrix