Explore the world of Abstract Base Classes (ABCs) in Python through this informative EuroPython 2017 conference talk. Dive into three levels of difficulty, starting with polymorphism, collections, and delegation. Progress to understanding virtual inheritance, registering, and the concept of ABCs. Finally, delve into creating custom ABCs, working with metaclasses, and using ABCs as interfaces. Gain valuable insights into object-oriented programming concepts and learn how to effectively categorize objects and implement virtual inheritance trees. Suitable for programmers of various skill levels, this talk demystifies complex topics like metaclasses and makes them accessible to everyday developers.