It's how much text it can consider at a time when generating a response. Basically the size of the prompt. A token is not quite a word but you can think of it a

It's how much text it can consider at a time when generating a response. Basically the size of the prompt. A token is not quite a word but you can think of it as roughly that. Previously, the best most LLMs could do is around 32K. This new model does 1M, and in testing they could put it up to 10M with near perfect retrieval. As the other comment mentions, you can paste the content of entire books or documents and ask very pointed question about it. Last year, Anthropic was showing off their 100K context window, and that's exactly what they did, they gave it the content of The Great Gatsby and asked it questions about specific lines of the book. Similarly, imagine giving it hundreds of documents and asking it to spot some specific detail in there.