This document discusses inter-thread communication in Java. It explains that inter-thread communication allows threads to communicate with each other using the wait(), notify(), and notifyAll() methods of the Object class. It provides details on how each method works, when they should be called, and how they allow threads to transition between waiting, notified, and running states. The document also provides a code example to demonstrate how wait() and notify() can be used to coordinate threads accessing a shared resource.