On JNDI...

naming service - allows you to look up an object given its name

naming and directory functionality
javax.naming
javax.naming.directory

context interface: looking up, binding/unbinding, renaming, creating/destroying subcontexts

initial context: starting point for performing name resolution.
subcontext: a name in one context object can be bound to another context object that has the same naming convention (for example, /usr/local, local is a subcontext of usr and /usr is a context. In vizxlabs.com, com is a context and vizxlabs is a subcontext.)

directory service: an extended naming service that allows name-object mapping and also allows the objects to have attributes. Looking up an object will also get you its attributes. An object can be searched based on its name or its attributes.

A directory object represents an object in the computing environment.