What is Active Directory?
Active Directory is the integrated, distributed directory service that is included with Microsoft Windows Servers. Integrated with Active Directory are many of the applications and services that previously required a separate, distinct directory and userid/password to be managed for each application or service. In Windows NT 4.0, for example, a directory was required for the domain itself, a separate directory for Exchange mailboxes and distribution lists, and separate directories for remote access, database, and other applications. In some cases, separate passwords were required for each application. With Active Directory, the administrator of the organization can add a user to Active Directory and through that single entry enable remote access to the network, enable the same user account for Exchange messaging, that same user for database access for accounting, client relationship management, or other applications. Not only is it possible to use Active Directory as a multi-purpose directory in this fashion but by doing so a company enables single sign-on for its users. Once a user logs in to Windows their Active Directory credential is the key that will automatically unlock all of the applications or services that they have been enabled for, including 3rd party applications that utilize Windows integrated authentication.
By creating a link between user accounts, mailbox accounts, and applications, Active Directory simplifies the task of adding, modifying, and deleting user accounts. When an employee gets married and changes their name, a single change in Active Directory can change the user information for all applications and services. When a user changes their password in Active Directory, they do not have to remember different passwords for their other applications. When a group of users is created such as the “sales group,” users can e-mail the group to send a message to all users, administrators can allow security access to resources based on the group name, and users can look-up members of a group by expanding the group information. This is just one example of how Active Directory simplified many administrative tasks and processes that, in the past, involved disparate applications, servers, and services.