PID: What is it?

Process ID is nothing but a unique identification number that helps to identify a particular process in Linux. PID’s are 16 bit number’s that are sequentially assigned to different processes one after the other.

INIT is the only process that gets the same PID number each and every time. INIT is the first program that’s run by a Linux system, due to which a process id number of 1 is given to it.