For morbidly curious this book gives us a little more insight into the five factions what they mean etc... and it also goes into detail about why each faction has that particular name which is very useful it also explains what they mean too if you're interested little snippets of what each faction does this book is for you plus it has snippets from Allegiant too.

I got this with the latest book set of the Divergent series (2013 re-release editions) I don't know the official name for them anyway.