A set of models that guides you in your use of the directory; a data model that describes what you can put in the directory; a naming model that describes how you arrange and refer to directory data; a functional model that describes what you can do with directory data; and a security model that describes how directory data can be protected from unauthorized access.
The LDAP protocol itself.
An API for developing directory-enabled applications.
LDIF, a standard interchange format for directory data.
Understanding and Deploying LDAP Directory Services, 2002 New Riders Publishing