A directory service should be thought of as a tool to help administrators manage network resources. Like any tool, the better designed it is, the more useful it will be. In its default configuration, Active Directory is a useful directory service, but its real power is apparent when thought has been put into its design and configuration. An efficient Active Directory design that reflects how a business is organized improves the ease and efficiency of managing a Windows network. Likewise, correct configuration of Active Directory is paramount to a smoothly running and secure network. You learn more about organizational units, how to use them in a hierarchical design, and how to manage access to them.