The AI Encyclopedia

What is AI, really? Why do large language models sometimes make things up with a straight face? How do you regression-test a prompt? Can you work through attention by hand? When should an agent stop and wait for a human?

The AI Encyclopedia: From Understanding and Using to Building and Research turns a complete three-volume AI textbook into an app you can read, experiment with and practice in. From understanding AI and using it for real tasks to math and code foundations, machine learning, deep learning, large language models, image / audio / video, creating with AI, agents, training and systems engineering, real products and research methods: a preface, 12 parts and 72 chapters, and Appendices A–E — in English, Chinese, or both side by side.

READ
• English, Chinese or side-by-side text; in a single-language mode, tap a paragraph to see it in the other language. The interface is available in English and Chinese.
• Guided and Full reading modes: Guided folds long code, outputs, big tables and references into one line so you can follow the main thread
• 191 figures, zoomable full screen; typeset math; wide tables turn into cards on iPhone
• Tap a term for its definition; highlights, notes and bookmarks; find in page; paper, sepia and night themes
• "Explain simply": select a passage and get it re-explained by Apple's on-device model (iOS 26 on supported devices; text never leaves the device)
• Works on iPhone and iPad, with a chapter sidebar on iPad

EXPERIMENT
• 69 interactive labs — at least one for every chapter — that reproduce the book's own examples and numbers: rules vs. learning on a spam filter, the learning rate in gradient descent, BFS and A* pathfinding, a neural network playground, convolution, BPE tokenization, causal attention by hand, temperature and sampling, 2-D diffusion, why a RAG system answers wrong, the agent loop, a prompt-injection sandbox, a GPU memory estimator, reproducing a number from a classic paper…
• 12 branching scenarios: play an analyst, an engineer or a product lead; read logs, chats, metrics and tables; make the call, watch the metrics move, and reach one of several endings
• An arcade: Term Rush, Fermi estimates, true-or-false quickfire and a daily challenge

PRACTICE
• 360 drills in six formats — order, match, sort, fill in, estimate, spot the error — and the ones you miss come back the next day
• A quiz for every chapter, plus quick checkpoint questions while you read
• 326 exercises with layered hints, worked answers, self-rating and spaced review
• 463 term flashcards and 508 key-point cards
• A knowledge map of all 72 chapters and their prerequisites; 4 reading routes and a 5-question diagnostic to find where to start
• Daily goals, streaks, a skill ladder and progress for every part

FREE VS. FULL BOOK
Free to read in full: the preface, Appendices A–E, and Part 1 "Understanding AI" and Part 2 "Using AI for Real Tasks" (chapters 1–12). Every other chapter has a free preview of its opening and first section. The labs, exercises, quizzes and drills of chapters 1–12 are free, plus one sample lab from each later part and two scenarios. The arcade, flashcards, key-point cards, search, knowledge map and reading routes are always free.

The Full Book is a one-time purchase, not a subscription. It unlocks all 72 chapters, 69 labs, 360 drills, 12 scenarios and every chapter's quiz and exercises, works on all your devices with the same Apple Account, and supports Family Sharing.

GOOD TO KNOW
• No ads, no account, works offline. Your study records stay on your device — we collect no data.
• Company and product names mentioned in the book are used for illustration only and belong to their owners.