My wife has a Chrome Book that I want to backup.  I've read several articles about making an image of a Chrome Book but I fail to understand exactly what I'll have after I follow the instructions.

From what I'm reading it appears that the backup will only restore the Chrome Book to factory settings.  I want to back it up so should it fail I can restore it to the current state.  I don't want to lose all the emails, all the pictures and all the links.

If somebody can explain both how to back it up and what exactly I'll have once it's backed up my wife would greatly appreciate it and so would I.

I have  16GB flash drive and that is the amount of space or memory in her computer. 

Thank you for any help.