There are a lot of good resources on the internet that explain forking reasonably well in far more detail than I’ll provide here. :)

Quick answer:

1. Node.JS is single threaded. There may be situations where using more than one process/thread could improve the performance of an application. Forking is the act of creating a child process that is a clone of the parent. It has all of the state/etc. of the parent, but in it’s own isolated container. Using an interprocess communication channel (often Pipes), the parent and child can communicate as necessary. That’s Linux/OSX. Now, Windows has a different model and doesn’t have the same functionality. In Windows, you can create a new process (CreateProcess) or a new thread (CreateThread). The difference when calling CreateProcess is that the child process does not inherit the state of of the parent. So, for Node.JS, when using child_process.fork, on Windows it’s going to create a new process and then initialize the Node engine in the new process. As it’s a new instance of the V8 engine anyway, the functional difference between the two operating systems is subtle.
2. And by now, the answer to your second question should be more obvious as fork creates a new process on each operating system, just the technique is different.

I believe the cluster module of Node uses forks to manage multiple processes.

I have few questions on forking.
1) What is the use of forking, why should we be using it ?
2) Does the forked process is same as the main process ?

Thanks
Rajkamal