Three million copies. Sixteen languages. Four editions. Python Crash Course is the book that taught a generation to program, and the 4th edition meets the moment it's publishing into. Author Eric Matthes addresses AI coding assistants directly and practically, not as threats to learning, but as tools that work best when you actually understand what they're producing. What's new and what's included in the 4th edition: Updated throughout for Python 3.15, with current syntax, libraries, and best practices; A new environment management workflow using uv, the fast modern Python package manager; VS Codium replaces VS Code as the recommended editor; New 'What I've Learned' exercises that build a personalized knowledge document readers use to calibrate AI assistant responses to their actual skill level; Direct, practical guidance on using AI coding tools without outsourcing understanding; Three complete projects carried forward from earlier editions and fully updated: A game built with Pygame, A data visualization tool using Matplotlib and Plotly, A deployable web application built with Django. The foundation is the same. The world around it has changed, and this edition acknowledges it.