Brain labPlay → read → next · ~6 min

Tutorials · Chapter C (3/4) · ~6 min

Tokens — how AI reads text

Play → read → next

Watch text shatter into tokens on a conveyor.

Simulation game

Token factory

Hit Start — watch the sentence shatter into token chips on the conveyor.

INPUT

ChatGPT helps plan dinner!

5tokens

Recap

What you just did

You broke a sentence into tokens — the small pieces an LLM actually counts and predicts. A word might be one token, or several; punctuation and spaces count too.

Teach

How it works

Think of tokens as LEGO bricks of text. The model’s job is: given the bricks so far, what’s a good next brick?

  • Longer prompts use more tokens
  • Responses also spend tokens
  • Every model has a maximum it can hold at once (that’s the next lesson: the context window)

Use it

When you'd use this

  • Trim a long dump of notes before pasting into chat
  • Prefer bullet goals over giant copy-pastes
  • Estimate whether a document will “fit” before you ask questions about all of it

Watch out

Watch out

Token count ≠ word count. Fancy formatting and repeated boilerplate burn tokens without helping the answer.

Try next

Try this next

Take one chat message and rewrite it half as long without losing the goal. Same ask, fewer tokens.