What you should never share · Lesson 7

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Ask it what it does with your words

From memory

Lesson 6

You are about to use it. Ask the tool what happens to what you type, then go and check one of its answers against the settings screen itself.

Ask your own tool

In plain English, answer three questions about this chat. One: is what I type here used to train the model? Two: could a human being at your company read this conversation? Three: exactly where in the settings do I turn training off? Name the menus in order. If you are not certain of the current answer, say so plainly instead of guessing.

Now check it. The wording changes as companies rename things, so here is how to find the switch rather than what it is called. Open your settings and look for the words train, improve, activity or data. It sits under one of those in all four tools. In August 2026 it was called "Improve the model for everyone" in ChatGPT, "Model Improvement" in Claude, "Keep Activity" on Gemini's activity page, and something like "AI Data Retention" in Perplexity. If those names have moved on, the four words above will still find it.

I found the training switch in the tool I use
I know whether it is currently on or off for me
I decided whether to leave it as it is or change it, rather than closing the page without looking

Turning it off is worth doing. Be clear about what it does not do. It stops your chats training future models. It does not delete what you have already sent, it does not make your chats private from the company, and it does not put them out of reach of a court. Google says the rule plainly in its own guidance for Gemini: "Please don't enter confidential information that you wouldn't want a reviewer to see or Google to use to improve our services." Google also says that chats picked for human review are kept for up to three years and are not removed when you delete your activity.

Lesson 07 · Knowing what to trust

By the end you can

Find and set the training switch in your own tool
Spot the private information hiding in an ordinary document
Write a do-not-paste list you can hold in your head
Prepare one document so it is safe to paste

What you need

Whichever tool you use most, and somewhere to write a few lines you will keep. Nothing here asks you to paste anything real.

Fundamentals of AI

What is actually in an ordinary document

In the box below there is a short made up email, sitting underneath an instruction addressed to the AI. Ignore the instruction for now. Read the email itself, the way you would read it if it landed in your inbox. Every name, number and address in it is invented. Read it, then answer the one question under the box before you copy anything.

Read the email. The copy button is for after your guess.

Act as a privacy reviewer. Below is a fictional internal email used for training purposes. List every separate piece of information in it that could identify a real person, reveal something private about a person, or damage the organization if it became public. Group your list under short headings. Do not rewrite the email.

The email. Read this before you paste anything.

From: Dana Whitfield, HR To: Priya Raman Subject: Adjustments for Tom Bexley Priya, Following Tom Bexley's return on 4 March, here is the note for his file. Tom's home address is 12 Larkspur Lane, Fenwick FN4 8QN and his mobile is 07700 900412. Date of birth 19 July 1988. Payroll reference FR-88214. Tom has been signed off with a recurring back condition and his consultant has recommended a phased return, three days a week until June. His salary is being held at 41,500 during the phased period. Please do not circulate. The Fenwick site closure is still unannounced and Tom's role is one of the eleven affected. Board sign-off is expected on 20 March. Dana

Guess first

Before you paste it: how many separate things in that email would you call private?

Fewer than fiveFive to tenMore than tenNo idea

Nobody else sees this and nothing here is marked. Being wrong here is worth more than being right.

Paste the list it gave you

Check your own work0/3

It treated the back condition and the phased return as private in their own right, not as ordinary HR admin. Health is the category people forget fastest
It flagged the unannounced closure and the eleven affected roles. That part is not Tom's secret, it is the organization's, and it is the kind of thing that ends jobs
It flagged the payroll reference. A reference number looks like meaningless clutter and is one of the easiest ways to tie a record back to a person

There are more than ten separate private things in that email. Three people named, a home address, a mobile number, a date of birth, a payroll reference, a health condition, a medical recommendation, a working pattern, a salary, an unannounced closure, the number of roles going, and a board date. Nothing in that email is unusual. No passwords, no bank details, nothing anyone would call a secret at a glance. It is the sort of thing that sits in an inbox and gets pasted into a chatbot with make this shorter on the front. That is the point.

Your own do-not-paste list

You cannot carry a policy in your head. You can carry one question and four categories. The question: would I be happy for this to be read aloud by a stranger, with my name attached, three years from now? Given what Google says about the three years, that is not a dramatic test.

Four things always fail it. One, other people's private business: health, pay, performance, family, immigration status, anything told to you in confidence. Two, keys and numbers: passwords, card and bank details, account and reference numbers, one-time codes. Three, anything not yet public: plans, prices, closures, deals, results before they are announced. Four, anything that is not yours to share: material you can see only because of your job, or that arrived with a confidentiality line on it.

Write your own three now. Not categories like customer data. Actual things you handle in a normal week: a named type of form, a named type of message, a named file. It stays in this browser on this machine. Nothing you type on this page is sent anywhere.

Your three, the ones you would not want read aloud

Check your own work0/4

Each one names a specific document, message or file I actually handle, not an abstract category
At least one is something I would have pasted without thinking twice before today
All three would fail the read-aloud question
I did not paste any of the actual material anywhere to write this

Make one document safe

Take the made up email from step 2 and produce a version you would be willing to paste. Work in a plain text note, not in the original file. Three rules. Type over the words, never cover them: a black box or black highlight hides text on screen and leaves it in the file, which is how real organizations have leaked documents they believed were safe. Keep the sense: swap names for labels you use consistently, like PERSON A and PERSON B, so the meaning still holds. Delete what you do not need at all, because the best version of this is removal. And paste the words rather than uploading the file, because files carry author names, comments, tracked changes and earlier drafts that the page in front of you does not show.

Check your version

Below is a document I have tried to make anonymous. Act as a privacy checker. First, list anything left in it that still points to a real person, place or organization. Second, answer this separately: if someone already knew this organization, could they work out who this is about from what remains? Explain how, in two sentences. Do not rewrite the document. [paste your version here]

Paste what it found

Check your own work0/3

It either found something I thought I had removed, or confirmed nothing identifying is left
On the second question it pointed out that what remains still narrows it down, most likely the named site plus the small number of people affected plus the date. Taking a name out is not the same as making something anonymous
I can still follow who is who in my version. If the labels made it unreadable I cut too much, and the tool will give me a worse answer

I have one copy of that email with the private parts typed over rather than covered up
I have my three line do-not-paste list written down
I know that a black box does not remove anything

Where that leaves you

You now know what you will not hand over, and you have one document proving you can prepare something safely. Next, the four tools side by side, because they are not the same, and the differences that matter are not the ones the advertising talks about.

Next: Choosing between the four tools