The first question you could ask would just be this: "Why in the hell should I use docker? I have a development machine running Apache and PHP and Mysql. And now Docker?". Yes you are right. All of these are available on development machines. Let me explain by an example why this could be a problem:
Drush for Developers, Second Edition, takes common challenges in Drupal projects and solves them using Drush. This book starts with the different installation approaches for Drush and its command structure. It then moves on to perhaps the trickiest challenge in Drupal projects: keeping code and configuration together during a project's lifetime. Next, we will deep dive into the tasks needed to keep a website under control and learn how to run, automate, and monitor them effectively.
Error validating and debugging our Drush commands is a must and this book has a whole chapter on that topic. The magic of managing remote Drupal projects through Drush site aliases is explained in the following chapters through a practical example. Finally, the book wraps up by putting in practice all the concepts covered in previous chapters in order to implement a development workflow for a team.