Active Directory is the LDAP-compliant directory server included with Windows server operating systems.

Active Directory stores all Windows operating system information, including users, groups, and policies. Active Directory also stores information about network resources (such as databases) and makes this information available to application users and network administrators. Active Directory enables users to access network resources with a single login. The scope of Active Directory can range from storing all the resources of a small computer network to storing all the resources of several wide areas networks (WANs).