//ret.cwell, there are three ways for the processes to exit: -
1. Voluntary exit (implicit)Voluntary exit can be implicit e.g. in case of return and explicit e.g.
2. Voluntary exit (explicit)
3. Involunatary exit
in case of a call to exit(). Involuntary exit is like being killed by a
third process, receiving a SIGSTP signal (or other signals whose default ot set
behavior results in terminating the process).