In the parent process, the return value of the fork is the PID of the newly created child process. This PID value is a positive integer representing the child process, and it allows the parent process to identify and manage the child process. The fork’s return value of 0 in the child process signifies that it is the child process. This return value of 0 distinguishes the child process from the parent process, as the parent receives the PID of the child.