Directory Access Protocol (DAP) was established by the International Telecommunication Union (ITU) in the X.500 series that looked for an electronic analog of a telephone directory book. DAP protocol was chosen for searching electronic directories, but it was too complicated for Internet implementation. Therefore, people dealing with the Internet simplified it and developed a new protocol. For naming the new protocol, they simply added the word ‘Lightweight’ at the beginning of DAP.
The architecture is simple: On the server, there is a particular directory (database), and an LDAP server that enables clients to access the database through the LDAP protocol.
Support from Operating Systems
Most email clients contain an "Address book" tool that can access LDAP servers. At present, most server distributions contain an LDAP server (for example, Active Directory in Windows 2000/2003).
Security
Similar to HTTP, LDAP...