Directory Services

A network service is a mechanism that identifies resources (printers, file servers,
domain controllers, peripheral devices) on a network and provides a way to
make them available to users and programs. A network directory service contains information about these different resources, providing a naming scheme,
and a hierarchical database that outlines characteristics such as name, logical
and physical location, subjects that can access them, and the operations that can
be carried out on the resources.
Network directory services provide users access to network resources transparently without needing to know their exact location and access steps required
to access them. These issues are taken care of for the user in the background.
Some examples of directory services are Novell’s Netware Directory Service
(NDS) and Microsoft’s Active Directory