What is the purpose of fork()?

Question

In many programs and man pages of Linux, I have seen code using fork(). Why do we need to use fork() and what is its purpose?

Answer 1

fork() is used to create child process. When a fork() function is called, a new process will be spawned and the fork() function call will return a different value for the child and the parent.

If the return value is 0, you know you're the child process and if the return value is a number (which happens to be the child process id), you know you're the parent. (and if it's a negative number, the fork was failed and no child process was created)

http://www.yolinux.com/TUTORIALS/ForkExecProcesses.html