LDAP (Lightweight Directory Access Protocol) serves as an Internet phonebook. When using e-mail programs like Outlook, Eudora, and Netscape, LDAP lets you lookup people's names and find their e-mail addresses, phone numbers, and office location. Of course, this assumes that you work inside a company or university where the net administrators have setup such a server for your use. The history of LDAP is within the X.400/X.500 international standards for e-mail. These were standards developed because things like Internet e-mail were too simple to handle all possibilities. X.400/X.500 was developed to be a more generalized service. Unfortunately, it was also so complicated that unless you were a huge corporation or government, you couldn't afford to deploy it.
LDAP is a "meet-in-the-middle" approach. It is a lightweight/simplified form of X.500 directory services. This means it is more generalized than the standard Internet services, yet simple enough that anybody can implement it.
One of the exciting things about LDAP is that it is more generalized. Think of it as a phone book that not only stores a person's phone number and e-mail, but also their picture and any other information.
LDAP clients have been built into most e-mail programs that you might use, including Microosft Outlook, Qualcomm Eudora, and Netscape Communicator. LDAP servers are part of numerous backend e-mail servers like Microsoft Exchange, Novell, and so forth.
