The Lightweight Directory Access Protocol (LDAP) is an application protocol for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network. In the early engineering stages of LDAP, it was known as Lightweight Directory Browsing Protocol, or LDBP.

Protocol
By TCP connecting to an LDAP server client starts an LDAP session , called a Directory System Agent (DSA), (default port 389)
The client then sends an operation request to the server
Then the server sends responses in return. With some exceptions
The client does not need to wait for a response for sending the next request
The server may send the responses in any order
All information is transmitted using Basic Encoding Rules (BER)

Operations
StartTLS — (Transport Layer Security extension for a secure connection)
Bind — authenticating
Search, Compare, Add, Delete, Modify (move/rename) an entry
Abandon — abort a previous request
Extended Operation
Unbind — close the connection (not the inverse of Bind)

Next Post will explain how to create LDAP from Apache Directory Studio