This book demonstrates the basic concepts of Object Oriented Programming (OOP) methodology, such as: Encapsulation, Polymorphism, Inheritance, Abstraction, Overloading, Error handling, ... . These concepts are illustrated and supported with practical examples coded by using C++ language. So, the theory and the implementation are gathered in this book. The reader should have a pre-knowledge in procedural programming methodology using C++ basic instruction set as a prerequisite to understand this book.