Lesson 1

Tokenization

How AI reads text

🧩 How does AI read text?

AI doesn't understand letters directly. It breaks text into pieces — tokens.

Step 1

We start with the original text as one piece

Hello world!

💡 Key insight:

  • A token isn't necessarily a word. It can be part of a word or even a punctuation mark.
  • Common words = 1 token. Rare words = multiple tokens.
  • More tokens = more expensive AI request.