Four of the folders here correspond to a project in the book. As you
read the book, you should add scripts to these folders. That will help
you understand what the different projects teach.

Other folders aren't projects. They store files used as examples
throughout the book. 

The first two project files have subfolders named 'snapshots'. If the
book says, "make a script that does X", you try, but you can't get the
promised result, you can copy those files up into the main folder to
get yourself moving again.

However, I *strongly* urge you to type the script yourself. If you
always just copy it in, you won't build any "muscle memory" of typing
Ruby and you'll have a hard time with your real scripts.