A core area of Unix/Linux systems programming is learning how to correctly handle the all-important fork(2) system call, to create a new process on the system. Using the fork(2) correctly takes a lot of deep insights. This chapter helped the systems developer by providing several key rules of fork. The concepts learned—the rules, working with data, open files, security issues, and so on—were revealed via several code examples. A lot of details on how to wait for your children processes correctly were discussed. What exactly are orphans and zombie processes, and why and how we should avoid zombies was dealt with too.