Traditionally, directory services have been a tool for organizing, managing, and locating "interesting" objects in a computing system. "Interesting" objects are things users (and applications) need to do their jobs, such as printers, documents, e-mail addresses, databases, users, distributed components, and other resources.
In its simplest form, directory services are like the white pages of a telephone book: Using specific input (a person's name), a user can receive specific output (a person's address and telephone number). Directory services also provides the functionality of the yellow pages: Using general input (that is, where are the printers?), a user can receive a browsable listing of printer resources.
But directory services must do more as networked environments become larger and more complex—even before connecting to the global environment of the Internet. The next generation Windows NT Directory Services were created for this next generation challenge of unifying and bringing order to diverse name spaces.