Bruce Eckel's 'Thinking in Python' is a 2026 instructional book that presents Python programming concepts through a structured series of chapters. The content is divided into five parts: Foundations, Techniques, Patterns, Functional Programming, and Effects. Part I covers introduction, tour, containers, control flow, functions, modules and packages, classes, static typing, class attributes, and cleanup. Part II addresses testing, data classes as types, pattern matching, decorators, context managers, comprehensions, metaprogramming, performance, and concurrency. Part III enumerates design patterns including rethinking objects, the pattern concept, data transfer objects, iterators, singleton, template method, surrogate, factory, function objects, changing the interface, observer, state machines, multiple dispatching, visitor, composite and interpreter, flyweight, memento, pattern refactoring, simulation, and a pattern catalog. Part IV introduces functional programming foundations, toolkits, error handling, and assurance. Part V explores effect management, stateless programming concepts, and practical applications. The work is licensed under Creative Commons Attribution‑NonCommercial‑NoDerivatives 4.0, making it freely readable online, and provides book examples and exercise solutions on GitHub.