ELI5: How does ChatGPT manage to process an 845 page document and respond in under five seconds? Does it actually read the entire document, or is it using a different approach behind the scenes?

ChatGPT doesn’t actually read every single word of an 845-page document; instead, it uses a smart search system to find and focus only on the parts of the document that matter to your question.

Think of it like this: if you had a giant library with 845 shelves of books and someone asked you, “What’s the best pizza recipe in here?”, you wouldn’t read every book from page one to the end. You’d quickly scan the titles, open the most likely books, and look for the pizza section. ChatGPT does something similar:

• It first breaks the document into smaller chunks (like cutting a big cake into slices).
• Then it uses a search system to find the chunks that match your question [1][6].
• Only those relevant chunks are sent to the AI to “read” and answer [1].
• This is much faster than reading the whole thing, which is why it responds in under five seconds.