Context Window

A context window is the amount of text an artificial intelligence (AI) tool can hold in mind at once, covering both what you give it and what it writes back. Go past that limit and the earliest details drop away, as if the tool has forgotten how the conversation began.

It is like a desk of a fixed size: you can spread out only so many papers before older ones must be cleared to make room. The context window matters because it sets how much a tool can genuinely take into account, so a long document may need breaking up to fit within it.