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Tokens

  1. 01Tokens
  2. 02Memory card
  3. 03The model can't read
  4. 04Not words. Tokens.
  5. 05The emoji trick
  6. 06Try it yourself
  7. 07How many r's in strawberry?
  8. 08What the model actually sees
  9. 09Some languages cost more
  10. 10Why "cat" and " cat" differ
  11. 11Why not millions of tokens?
  12. 12So why not just use bytes?
  13. 13Context windows are measured in tokens
  14. 14Reinforce your understanding
  15. 15Question: Why not just use words?
  16. 16Question: Weird splits
  17. 17Quiz: answer
  18. 18What to carry out of this chapter
  19. 19Want to go deeper?
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Module VI

The Meaning of Words

Chapter II

Tokens

In this chapter

  • Not words, tokenswhy models split text into subword fragments instead
  • Context windows are measured in tokens, not words or characters
  • Weird splitsthe surprising places tokenization creates blind spots
  • Why this shapes what the model finds easy and what it finds strangely hard

A language model never reads the way you do.

Before any processing begins, text has to be broken into pieces. Not words, exactly. Something smaller and more practical: fragments that can be combined to cover almost any text efficiently, without requiring a vocabulary so large it becomes unworkable.

The pieces are called tokens. The way text gets split into them shapes everything that follows. It determines what the model finds easy to handle and what it finds difficult. It creates blind spots in places you might not expect. It means the model's relationship to language is different from yours in ways that matter.

It is easy to overlook because it happens before anything visible occurs. But it decides what the model can and cannot notice.

Citations