Context is everything
The model knows two things: what it learned in training and what is in this conversation. Learn what the context window is, why you should paste the material, and what a training cutoff means for recent questions.
Context window
All the text the model can take into account at one moment: any instructions the app gives it, your messages, its own earlier replies, and anything you pasted or attached. It has a size limit, measured in tokens. What is outside the window does not exist for the model.
A 3-page report pasted into the chat is inside the window. The same report sitting in a folder on your laptop is not.
TWO SOURCES ONLY
Training and the conversation
Everything the model says comes from two places. Training: general knowledge absorbed from a huge amount of text, frozen at some date. The conversation: whatever is in the window right now. It knows a lot about contracts in general. It knows nothing about your contract until you put it in the chat.
Tools that search the web or read your files don't change this rule. They work by fetching text and placing it into the window, where the model can then read it.
Check yourself
Omid asks an assistant, "Summarise our company's leave policy." He gets a tidy summary that doesn't match the real policy at all. What should he do next?
- Tell it the answer is wrong and ask it to try harder and be more accurate this time
- Ask the same question in a new chat
- Add the company's name so it can recall the policy
- Paste the actual policy text into the chat and ask again
Show the answer
Paste the actual policy text into the chat and ask again
Yes. The policy was never in the window, so the model wrote what a typical leave policy looks like. Give it the text and it can summarise the real thing.
Give it the material
Weak prompt
"Write a reply to an unhappy customer about a late delivery."
The model invents the customer, the delay and your shop's rules. The reply sounds fine and fits nobody.
Improved prompt
"Here is the customer's message: [pasted]. Here is our delivery policy: [pasted]. The parcel is 6 days late because of a courier strike. Write a reply that apologises, explains, and offers what the policy allows."
Nothing left to invent.
Below are my notes from today's team meeting. Using ONLY these notes, write a 4-line summary I can send to my manager, then list who has to do what.
Notes:
- launch moved from 10th to 17th, designer ill
- Reza finishes payment page by Thursday
- Mina to call the printer about flyers
- budget not discussedSummary: The launch has moved from the 10th to the 17th because our designer is ill. The payment page is on track for Thursday. Flyers are still to be arranged. Budget was not discussed.
Actions:
- Reza: finish the payment page by Thursday
- Mina: call the printer about flyers"Using ONLY these notes" tells the model to stay inside the material you gave it instead of padding the summary from general knowledge.
Check yourself
Maryam explained her whole project in a chat last week. If she opens a brand-new chat today, she can safely assume the assistant still has those details.
Show the answer
False
A new conversation normally starts with an empty window. Some products have a memory feature that carries a few notes across chats, but you can't count on it holding the details you need. Paste a short summary of the project at the top of the new chat.
FROZEN IN TIME
The training cutoff
Training stops at some date, the training cutoff. The model learned nothing after it: not last month's news, not the newest version of an app, not today's prices. On its own it may not even know today's date. Ask about something recent and it will either say it doesn't know or, worse, answer confidently from an older world.
Ask "what's the newest phone from this brand?" and you may get the model that was newest when training ended, presented as current.
Check yourself
Can the model know this from training alone, or does it have to be in the conversation?
- How to structure a formal complaint letter
- What your teacher wrote in the assignment brief
- The main causes of the First World War
- What was decided in your meeting this morning
- The result of last night's football match
- What a balanced weekly meal plan looks like
Show the answer
Training is enough: How to structure a formal complaint letter, The main causes of the First World War, What a balanced weekly meal plan looks like
Must be in the chat: What your teacher wrote in the assignment brief, What was decided in your meeting this morning, The result of last night's football match
The context check, before you send
- What does this task depend on?
A document, an email thread, a brief, some numbers? Paste it. Don't describe it from memory when you can give the real thing.
- What's my situation?
Who you are, who it's for, what happened so far. Two sentences are usually enough.
- Is any of it recent or private?
If it happened after the cutoff or never appeared in public, the model can't know it. Supply the facts and, if dates matter, today's date.
- Has the chat grown long?
Restate the key rules, or start fresh with a summary.
Check yourself
Ali needs the current entry rules for a country he's flying to next week. His assistant gives a confident list. What is the sensible move?
- Trust it, because the list is detailed and specific, and entry rules don't change often enough to worry about
- Ask it to confirm that the list is up to date
- Check the embassy's or airline's official page, then paste that text into the chat
- Rephrase the question more politely and compare the two answers
Show the answer
Check the embassy's or airline's official page, then paste that text into the chat
Right. Rules like these change, and the model's knowledge is frozen at its cutoff. The current official text is the source; the assistant can then help him read it.
Lesson recap
- The context window is everything the model can see right now; outside it, nothing exists for the model.
- It knows general things from training and specific things only from the conversation, so paste the material.
- A new chat usually starts empty, and long chats lose early details: restate or summarise.
- Training has a cutoff date. For anything recent, bring the current facts yourself.