Mozilla Firefox is a great example of a piece of open source software. Of course, a lot of these recent chapters discuss how open source software is used in Cyber Forensics.
In order to better understand this, choose a piece of open source software (either linux or something mentioned in the chapters, or a favorite of yours) and find a little bit out about the evolution of the project.
Try to relate that back to the discussion of cyber forensics, what are the benefits of open source software (obviously cost, but what else) and what are the drawbacks (potentially the scope of features/ support).