An interactive tutorial
How language models
actually work, from the ground up.
A first-principles path through tokens, embeddings, attention, and the machinery behind LLMs — built up step by step, with worked examples and runnable code that make it stick.
9 lessons across 1 chapter · ~44 min · free to read
Highlight & note
Mark up the text. Your highlights and notes sync across devices.
Spaced review
Key ideas resurface on an FSRS schedule so they stay learned.
Exercises
Predict tokenizer output, trace algorithms, check understanding — with instant feedback.
Read freely — no account needed
Every chapter is open to everyone. Signed out, the site stores nothing on a server and tracks nothing — you lose no content by staying logged out.
Sign in to make it yours
A free account keeps your reading progress, highlights, and notes with you and in sync across devices — plus spaced review to help it stick.
✓ You're signed in — your personal layer is on.
Personal features are rolling out as we build them.
Your privacy: reading never requires an account and is never tracked. An account (handled by our auth provider, Clerk) stores only your sign-in identity and your own progress and notes — never sold, never used for ads. You can delete your account at any time.