Plain English
Token
A small chunk of text, often part of a word. AI reads and writes in tokens, and prices count them.
The unit an AI model reads and writes in: a word, part of a word or a punctuation mark. In English, a token averages roughly three-quarters of a word, depending on the model, and both context windows and per-use prices are measured in tokens.
Why it matters
Tokens are what you pay for on per-use plans and what fills up the context window. Long documents and long chats use more of both.
At work
A 300-word email is roughly 400 tokens, so a price quoted “per million tokens” covers a lot of emails.
Think of it like syllables for a machine: it doesn’t read whole words the way you do, it reads pieces, and counts everything in them.
Related terms
Where it appears