Hi Albert, Thanks for your question. Spring Quickly is a book designed for beginners. I decided to write Spring Quickly after receiving feedback from many of my students about not finidng a book to help them understand Spring step by step from zero. Take for example Spring in Action by Craig Walls. It is an excellent book. I enjoy reading every new released edition. But it is not a book for someone who didn't use Spring before (or even worst, who didn't use a framework before). So Spring Quickly comes to fill this gap and help a developer with zero or very little knowledge on Spring get good enough to work on production-ready apps. Now, does Spring Quickly teach you everything about Spring? Of course not! Spring is a massive ecosystem, this is why you find so many books about Spring out there. For example, I wrote a full book only on Spirng Security. If you ever read Spring Security in Action, you'll find 560 pages of juicy Spring Security examples
