Is it possible to start a thread without creating a separate process?

Yes, a thread is a lightweight unit of execution within a process. Starting a thread does not require creating a separate operating system process.

A process is a separate program with its own address space, while a thread is a unit of execution within a process that shares memory with other threads of the same process.

For example, in Java, you can create and start a thread like this:

Thread thread = new Thread(() -> {
    System.out.println("Executing in a separate thread");
});
thread.start();

Here, a new thread is started within the current process without creating a new OS process.