Tokens and the context window

In any AI chatbot you already use:

1. Start a new chat. Send: My favourite fruit is rambutan. Please remember that.
2. Start another new chat. Send: What is my favourite fruit?

Look at the second reply.

You're done when you can explain in one sentence why the second chat did or didn't know. (Usually it doesn't know, because a new chat is a clean desk. If it does know, the app has a memory feature that put that note back on the desk for you.)

• A token is a small piece of text. The model counts in tokens.
• The context window is the desk: the model only sees what's on it right now.
• A full desk loses early details. A new chat starts with a clean desk.

Next lesson (1.5): if the desk gets cleared, where should important things live? In files.