LDAP (Lightweight Directory Access Protocol) is an Internet protocol that email and other programs use to look up information from a server.As a protocol, LDAP defines the "language" used for client programs to talk to servers (and servers to talk to servers).
On the client side, a client may be an email program, a printer browser, or an address book.
The server may speak only LDAP, or have other methods of sending and receiving data—LDAP may just be an add-on method. LDAP also defines: Permissions set by the administrator to allow only certain people to access the LDAP database, and optionally keep certain data private. If N/A leave blank.