The Lightweight Directory Access Protocol (LDAP) is a query protocol, that responds by returning a "Whitepages-like" X.500 Directory Access Protocol entry. LDAP was formerly championed by Microsoft as their semi-proprietary alternative to the similar CCSO protocol. Just copy & paste the full address into your LDAP client, or the rare Browser that understands the URI "ldap://". Global LDAP servers attempt to be global lookup directories, often aggregating data from multiple local databases in with their own. Local LDAP servers focus their database on just one organization, such as a University or large business. Below are addresses for various publicly open LDAP servers.
[IANA Port assignment = 389]