Private browsing: what it actually hides and what it does not

When you open an incognito window, the browser is honest: its opening screen explains what it does and what it does not. The trouble is that nobody reads it, and the name suggests an invisibility that does not exist.

It is worth splitting into two lists.

What it does do

When you close the private window, the browser discards:

• The history of pages visited.
• The cookies created during the session.
• The form data you typed.
• The signed-in sessions: close the window and you are logged out of everything.
• The cache from that session.

It also starts without your existing cookies. That has a useful side effect: sites see you as a new visitor, with no accumulated purchase history or preferences.

What it does not do

And here is the misunderstanding:

• Your internet provider sees which domains you connect to. Just as always.
• Your employer or university, if you are on their network or device, does too. The record is on the network, not in your browser.
• The sites you visit still see you: your IP address and a set of browser characteristics that, combined, form a fairly identifying fingerprint.
• The moment you sign in, it is over. As soon as you log into your Google account or a shop, that service knows exactly who you are, incognito or not.
• Downloads and bookmarks stay. Whatever you save is saved.
• The machine’s administrator may have logging by other means.

The honest summary: incognito protects you from the people who use your computer, not from the companies on the other end of the connection.

When it is exactly the right tool

It has good uses, and more of them than people assume:

• A borrowed, shared or public computer. An internet café, a relative’s laptop, a hotel machine. Close the window and no session or history remains. This is the case it was designed for.
• Using two accounts of the same service at once, one in each window type.
• Checking how a page looks when signed out. Very useful for seeing whether something works for the public or only for you.
• Shopping for a present without it turning up in the history or in the adverts in the living room.
• Debugging a site without old cookies in the way.

A note on flights: the belief that incognito makes tickets cheaper is more folklore than anything. Prices sometimes shift because session cookies are gone, but pricing depends on many other factors. It is useful for comparing from a clean slate, not for outsmarting the system.

On someone else’s computer, incognito is the floor

If you are going to use a machine that is not yours, a private window is the minimum, not the maximum:

1. Use incognito from the start, not halfway through.
2. Do not save passwords if the browser offers.
3. Close the window when you finish, not just the tab.
4. If you signed into anything important, sign out actively first.
5. If the machine is genuinely unknown, assume there may be a keylogger and do not type anything critical. It is the same test you apply to a network you do not control in public Wi-Fi: which risks are real.

The parallel with AI

The confusion repeats almost exactly in the temporary chat offered by AI assistants: it never enters your history and is not used for training, but the conversation still leaves your machine and is kept for a while for abuse monitoring. Discreet, not invisible — precisely like incognito. The detail is in how to delete your ChatGPT history.

What to do if you genuinely want to reduce the trail

Incognito is not the tool for that. What does help, in order of real usefulness:

• A browser with tracker blocking on by default.
• A search engine that does not build profiles.
• A content blocker for third-party trackers.
• A trustworthy VPN if what you want is for your provider or the local network not to see the domains. It changes who sees you; it does not remove the trail: you move from trusting your provider to trusting the VPN.
• And for what is already published about you, the different job described in how to delete your personal data from the internet.

The short version

• Incognito clears history, cookies and sessions from your machine when the window closes.
• It hides nothing from your provider, your employer or the sites you visit.
• The moment you sign in, the anonymity is gone entirely.
• It is the right tool for a shared or borrowed computer.
• Genuinely reducing your trail needs different tools, not this one.