Object-oriented code runs slower than procedural code but makes it easier to model and manipulate complex data structures. PHP has supported object-oriented programming since version 3.0 and since then it’s object model has been extended and reformed extensively.
This book is not going to try to teach object-oriented programming but will rather focus on the PHP implementation. It’s expected that you have at least some experience coding in PHP.
This is one of the three most important sections of your certification examination.