Applied OO is a collection of Guidelines that Don’t worry, the object-oriented programming is not reformulated here. From my point of view this is simply a logical further development to the topic object orientation and the successful mastering of it!
Since the beginnings of this paradigm, there have always been different interpretations of how the right application should look like. It led to different thought styles of object orientation.
Applied OO I finished thinking for myself in 2017. It is designed to focus on testable software, robustness and clean code. This has led to a significant reduction in the set of OO syntax usage.