01- What is LDAP

LDAP - Lightweight Directory Access Protocol

LDAP is a basically a Directory, as in a listing of objects (as people) with attributes.

Commonly it is used to hold user login information.

A directory might hold info like below,

UserName: briandg

Real Name: Brian Dolan-Goecke

Password: Simple

Phone Number; 651-555-5221

More commonly in a Unix System

briandg:$$oldpasswordwerehere%!1:5000:5000:Brian Dolan-Goecke,,,:/home/briandg/bin/bash

A LDAP Directory could also hold DNS info.  Because of the flexibility of LDAP it has been used for a variety different tasks.

Usually Directory Information is Hierarchal, or a Tree.  This information is also know as DIT, Directory Information Tree.

http://en.wikipedia.org/wiki/Lightweight_Directory_Access_Protocol