This book is a tutorial on the Python language and a classic in its domain. It’s the product of three decades spent using, promoting, and teaching Python, and dates back to the mid-1990s, when Python was still at version 1.X, and the web was just something developers mused about over lunch. Although the focus here is firmly on the present, that legacy naturally adds some historical context that will help you understand Python more deeply. Despite what you may have heard, the past matters, especially in knowledge-based fields.

Just as importantly, this book has always been based on live-and-in-person feedback from Python beginners struggling to learn Python for the first time. This feedback mostly owes to Python training classes taught over a period of two decades. While these classes have now gone the way of the dodo and Yahoo, this book takes care to retain its learner-inspired material because that’s much—if not most—of its value.

As a result, if you’re like most of the thousands of learners whose experiences have been captured here, you’ll probably find that this book works like a self-paced version of the Python training sessions from which it arose. You may sometimes even find that it answers your questions before they are asked because a host of learners before you have had the same queries. This isn’t clairvoyance; it simply reflects the fact that learning resources do best when they listen to learners.

It’s also worth noting up front that this book sometimes critiques Python changes while presenting them. Critical thinking is crucial in engineering domains—especially in one caught up in an arms race that convolutes tools used by millions of people. On some levels, Python remains a constantly morphing sandbox of ideas that too often prioritizes changer hubris over user need, and this book is not shy about calling this out. That said, the main goal here is to educate, not criticize, and opinions are always, well, opinionated. Although views here reflect decades of using and teaching Python, you should always judge the net worth of Python changes for yourself in whatever world you’ve been cast.

Changes in the sixth edition:

This edition drops coverage of the now-sunsetted Python 2.X line and updates its content to be current with Python 3.12 and the decade of changes since its prior edition. It also gives more focus to non-Windows platforms, including smartphones. Among its new 3.X content, this edition covers f-string literals, named-assignment expressions, match statements, type hinting, async coroutines, underscore digit separators, exception groups, module attribute hooks, star-unpacking proliferation, main-script package files, dictionary-key insertion order, positional-only function arguments, hash-based bytecode files, and other additions, deprecations, and changes.

Other noteworthy changes this time around:

• The Unicode content in the advanced part’s Chapter 37 is new and improved because this topic is now an essential in Python 3.X and the world at large.
• Usage coverage, including the new Appendix A, gives more focus to macOS, Android, Linux, and iOS because not all of this book’s readers use Windows.
• Most code-file examples now have numbered captions because the extra formality distinguishes them better in the book, and it’s worth the space.
• Some redundancy has been trimmed, but not all, because repetition is useful and even important in learning resources.
• Fictitious names in examples are more gender neutral: “Bob” is now an ambiguous “Pat” unless paired with “Sue” as before because it better defuses bias.
• The Monty Python references have been dropped because they can be confusing and might be divisive, and borrowing personality from media seems cheap.
• Both first-person voice and personal anecdotes have been globally sacked because you’ve bought this book to learn Python, not an author’s life story.