To learn more about processes in the UNIX System, consult the following references. Here are some useful books discussing how processes work in the UNIX environment:
Bovet, Daniel P., and Marco Cesati. Understanding the Linux Kernel: From I/O Ports to Process Management. O’Reilly, 2000.
Feiler, Jesse. Mac OS X: The Complete Reference. McGraw-Hill/Osborne, 2001.
Levi, Bozidar. UNIX Administration: A Comprehensive Sourcebook for Effective Systems and Network Management. CRC Press, 2002.
O’Gorman, John. The Linux Process Manager. John Wiley & Sons, 2003.
Petersen, Richard. Linux: The Complete Reference. 5th ed. McGraw-Hill/Osborne, 2002.
Robbins, Kay and Steve Robbins. UNIX Systems Programming: Communications, Concurrency, and Threads. 2nd ed. Pearson Education (Prentice Hall), 2003.
Watters, Paul. Solaris 10: The Complete Reference. McGraw-Hill/Osborne, 2005.
There is a useful web page on UNIX processes from an appendix of an O’Reilly publication, Practical UNIX and Internet Security:
http://www.unix.org.ua/orelly/networking/puis/appc_01.htm
and some others providing a background of the concept of processes at:
http://helpdesk.ua.edu/unix/tipsheet/tipv3n3.html
and
http://heather.cs.ucdavis.edu/~matloff/UnixAndC/Unix/Processes.html
and a printable .PDF file describing managing processes at:
https://www.stat.berkeley.edu/help/files/processes.pdf
These should provide background information as well as practical information.