Context Window
Definition
The amount of text an AI tool can "hold in mind" at once during a conversation. Older models had small context windows — they'd forget what you said at the beginning of a long conversation. Newer models have much larger windows. When a tool starts giving answers that seem to ignore something you said earlier, it has usually run out of context window.
Why It Matters
Knowing this exists explains a common frustration and gives you a practical fix: start a new conversation, or paste back the relevant context.
What does that look like in practice?
Halfway through a long chat the AI forgets a detail you gave at the start, and you've hit the edge of its context window.
What people actually mean when they say this
When someone says 'it forgot what I told it,' they usually mean the conversation outgrew the context window, not that the tool is broken.
Last reviewed: March 2026
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