Dive deep into various aspects of object-oriented programming in Python, design patterns, data manipulation techniques, and testing issues for complex object-oriented systems. Discussion of all concepts is supported by examples written specifically for this edition and practical exercises at the end of each chapter. All examples are coded to Python 3.9+ syntax and include type annotations for easy learning. Stephen and Dusty provide a clear, comprehensive overview of important OOP concepts such as inheritance, composition, and polymorphism, and explain how they work using examples of Python classes and data structures , which significantly simplifies the design. The text makes extensive use of UML class diagrams to make it easier to understand the relationships between classes. In addition to OOP, the book takes a detailed look at exception handling in Python, as well as functional programming techniques that overlap with OOP techniques. The book introduces not one, but two very powerful automated testing systems: unittest and pytest, and the final chapter discusses in detail the parallel programming ecosystem in Python. Gain a thorough understanding of how to apply object-oriented programming principles using Python syntax and learn how to create reliable and sustainable programs.