Uploaded January 2026 | Updated September 2026, 15 minutes ago

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Day 13/42: What Is a Context Window?

Yesterday, we broke down prompts.

Now we talk about memory.

The context window is how much text a model can see at once.

It includes:

your instructions,

the conversation history,

and the answer it’s currently writing.

When the window fills up, something has to go.

Usually, the oldest messages disappear.

That’s why long chats drift.

And why “remember this forever” doesn’t work.

Missed Day 12? Start there.

Tomorrow, we compare zero-shot and few-shot prompting.

I’m Louis-François, PhD dropout, now CTO & co-founder at Towards AI. Follow me for tomorrow’s no-BS AI roundup 🚀

#ContextWindow #LLM #AIExplained #short