At some point in the book, you will need to use git commit. This will fail unless some basic configuration is performed; you need to provide Git with your name and email address. Git will remind you to do this with a nice error message, but you may as well do it now.
This is also something to keep in mind if you are using a service such as Travis for continuous integration, and your test scripts need to perform some git merges; you have to provide a dummy name and email for the merging to succeed.