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CWContext Window Notes

Tokens, memory limits and long chats, in plain words

Reading list

  1. What is a token in an AI language model?

    A token is the chunk of text a language model actually reads. Here's how tokens differ from words and why the difference matters.

  2. What is a context window?

    A context window is the text a model can look at while it writes a reply. Here's what goes inside it and what sizes the makers publish.

  3. Why an AI chat forgets earlier messages

    A chat assistant can lose earlier details when a long conversation fills its context window. Here's how that works, from the makers' own docs.

  4. How many words fit in a token budget?

    A rule of thumb for turning tokens into English words and back, with a conversion table and the reasons it's only a rough guide.

  5. Input limits and output limits are different

    Why a reply can stop short even when your document fit. The window, the output cap and hidden reasoning tokens are separate things.

  6. How token-based pricing works

    How makers charge for AI use by the token, why input and output have different rates, and what cached input and reasoning tokens are.

  7. How to count tokens before you send

    How to check the size of a prompt with the makers' own token counters, and why a plain-text count can miss part of a request.