In Java multithreading, which method contains the actual body of work executed by a Thread (i.e., the code that runs on the thread's stack when scheduled by the JVM scheduler)?

Introduction / Context:
Understanding the lifecycle of a Java thread is essential for writing concurrent programs. A frequent confusion is between the method that starts a thread and the method that actually executes on the new thread.

Given Data / Assumptions:

• A class extends Thread or implements Runnable.
• The thread lifecycle includes states such as New, Runnable, Running, Blocked/Waiting, and Terminated.
• The JVM scheduler invokes user code on a separate call stack when appropriate.

Concept / Approach:
The start() method asks the JVM to create a new thread of execution, whereas the run() method is the entry point for the work performed by that thread. The developer places the thread's body (business logic) inside run().

Step-by-Step Solution:

Verification / Alternative check:
Calling run() directly from the main thread executes synchronously (no new thread). Only start() spawns a new thread that then calls run().

Why Other Options Are Wrong:

• start() → starts the thread but doesn't contain the work.
• stop() → deprecated, dangerous; not the body.
• main() → process entry point, not a thread's body.

Common Pitfalls:
Beginners often call run() directly, mistakenly assuming it starts a new thread.

Final Answer:
run();