a visual course

How ChatGPT
Actually Works

The one trick behind every chatbot: predicting the next word — in under half an hour.

A free, visual course on how large language models like ChatGPT actually work — from predicting the next word, to tokens, probabilities, temperature, the context window, and why they sometimes make things up. No math required.

Start with the next word →

Part 1 — The core trick

1

It's just autocomplete

A chatbot does one thing: guess the next word, add it, and repeat.

2

Tokens, not words

Models read text in chunks called tokens — sometimes a word, sometimes a piece of one.

Part 2 — Inside the prediction

3

A score for every word

At each step the model ranks the entire vocabulary by how likely it is to come next.

4

Careful or creative

A single dial — temperature — decides whether it plays safe or takes risks.

5

How it remembers

The context window is everything the model can see at once — and its hard limit.

Part 3 — Quirks & limits

6

Why it makes things up

It predicts what sounds right, not what's true — so it can be confidently wrong.