DEFINITION: X.500 Directory Service is a standard way to develop an electronic directory of people in an organization so that it can be part of a global directory available to anyone in the world with Internet access. Such a directory is sometimes called a global White Pages directory. The idea is to be able to look up people in a user-friendly way by name, department, or organization. Many enterprises and  … 
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X.500 PROTOCOL DEFINITION (continued): …  institutions have created an X.500 directory. Because these directories are organized as part of a single global directory, you can search for hundreds of thousands of people from a single place on the World Wide Web.

The X.500 directory is organized under a common "root" directory in a "tree" hierarchy of: country,organization, organizational unit, and person. An entry at each of these levels must have certain attributes; some can have optional ones established locally. Each organization can implement a directory in its own way as long as it adheres to the basic schema or plan. … 
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