X.500 is the set of
ITU-T computer networking standards covering electronic directory services such as
white pages,
Knowbot and
whois.
Compare: LDAP.
Article based on X.500 (http://foldoc.doc.ic.ac.uk/foldoc/foldoc.cgi?query=X.500) at FOLDOC (http://www.foldoc.org), used with permission.