Incognito Mode: What It Actually Hides, and From Whom

Open a private window and your browser stops writing things down. That is the whole feature, and it is a genuinely useful one. The trouble is that almost everything people hope incognito hides travels over the network rather than sitting on your disk, and a private window has no reach out there at all.

What a private window actually is

A private window is a separate browsing session with its own temporary storage. Chrome’s documentation puts it plainly: opening an Incognito window starts a separate session, and that session ends when you close all Incognito windows. Firefox and Edge describe the same shape, and all three stress closing every window rather than the one you were looking at.

That detail catches people out. Open a second private window to check something, close the first, and the session is still running. Nothing has been cleared. Microsoft’s documentation is specific here: Edge deletes browsing history, download history, cookies and other site data, cached images and files, passwords, autofill form data, site permissions and hosted app data when you close all InPrivate windows. Not the last tab. Not the window you finished with. All of them.

Everything else about your browser carries on as normal. The private window uses the same machine, the same network connection, the same installed fonts and the same graphics hardware, and in Edge’s case it can reach the passwords and form-fill data belonging to the profile that launched it. It is a fresh jar for storage, not a fresh computer.

The part that works exactly as advertised

On the device, private browsing does what the label says. Chrome retains no site data and no record of the sites you visited once the session ends, though it does keep cookies temporarily during the session so pages work. Safari is more specific again: web pages you visit and your AutoFill information are not saved, your open pages are not stored in iCloud so they do not appear when you check your tabs from another Apple device, and your recent searches are left out of the Smart Search field. Firefox erases your browsing history and tracking cookies when you close the last private window.

This solves a real problem, and it is the problem the feature was built for. Shopping for a present on a shared laptop. Looking up a symptom on the family computer. Signing into a second account without logging out of the first, which works because Chrome does not automatically sign you into your Google account or other websites in Incognito.

What survives anyway

Bookmarks and downloads. Every one of these browsers keeps bookmarks or favourites you create in a private session, and downloaded files stay on the disk. Apple’s wording is precise about the distinction: items you download are not added to the downloads list, but the items do remain on your computer. The record is gone, the file is not.

Extensions. Microsoft states flatly that Edge cannot prevent extensions from saving your browsing history while you browse InPrivate, and that extensions you have permitted will run in InPrivate windows. Whatever an extension chooses to log, it logs.

Anything the site wrote down at its end. Sign into an account during a private session and that account has a record of the visit. Deleting your side of the conversation has never deleted theirs.

Your IP address does not change

This is the misconception worth killing, and the browser makers say so themselves rather than leaving it to be inferred.

Mozilla says private browsing does not prevent the websites you visit from seeing where you are physically located, and does not stop your internet service provider logging what you do. Chrome says Incognito does not make you invisible, and that websites you visit and organisations managing your network, such as your school, employer or internet service provider, may be able to observe your activity. Microsoft says other people using the device will not see your browsing activity, but your school, workplace and internet service provider might still be able to access it.

Three vendors, three help pages, one answer. A private window is a control over your own storage. It is not a control over the network.

You can confirm this in about ten seconds. Open a private window, load your visible IP address, and compare it with the same page in a normal window. Same number, same provider, same approximate location. If you want that number to change, how to change your IP address covers the methods that actually do it, and what your ISP can actually see covers how much of your browsing stays visible from the network whichever window you use.

Chrome’s one exception, and it is narrower than it looks

Chrome has begun rolling out a feature called IP Protection, and it is the only mainstream thing that makes a private window do anything to your address at all. It deserves a precise description, because the summary version circulating online overstates it considerably.

Three conditions have to hold together. Google’s help page lists them as a chain: the domain must be on the Masked Domain List, the domain must be embedded as a third party, and the user must be browsing in Incognito. Only when all three hold does that domain get a masked address. It is enabled by default in Incognito, and users can switch it off. Under the bonnet it is a two hop proxy, the first run by Google and the second by an external content delivery network, arranged so that neither one sees both your address and your destination.

What it does not do matters more. It does not mask your address from the site you typed into the address bar, and Google is explicit that in a first-party context the real address is visible even when the domain is on the list. The masked addresses deliberately keep coarse location including country, because services need that to obey local law and to pick a language. Chrome’s own explainer states that the feature is limited to Incognito mode on Android and desktop, that access requires you to be signed into a Google account in Chrome before the Incognito session starts, and that enterprise-managed Chrome has it off by default. Google’s overview adds that the rollout reaches certain regions before it goes global, so it may not be available in your country yet.

Put that together and the honest reading is this. Your provider still sees everything. The site you actually visited still sees your real address. A subset of embedded third parties see a proxy address that still says which country you are in. That is a real improvement against cross-site tracking, and it is not the same thing as hiding your IP address.

Your fingerprint does not reset either

Clearing storage does not change how your device renders a canvas element, which fonts it has, or what your graphics card reports. A private window presents very nearly the same browser fingerprint as a normal one, which is why a tracker that has stopped relying on cookies is largely unbothered by which window you opened.

There is one meaningful exception, and it is Apple’s. When you use Private Browsing in Safari, advanced tracking and fingerprinting protection is turned on by default, blocking connections to data collection companies that use advanced fingerprinting techniques and stripping known tracking parameters out of URLs. That is a private-browsing feature which reaches past storage, and it is unusual. Most of what a private window does stops at your own disk.

The way to see where you actually stand is to run the Browser Fingerprint Test in a normal window, then again in a private one, and compare the individual signals rather than the headline. Most of them will not move.

What happens while the session is still open

Private browsing clears at the end, not continuously, and that gap is larger than most people picture. Microsoft is unusually frank about it, saying that InPrivate browsing does not keep you safer from malicious websites or provide additional ad blocking, and that websites can still personalise content for you during the session because cookies and site permissions are not deleted until you close every InPrivate window. Open a private window on Monday, leave it open all week, and it has been accumulating state all week.

Chrome does draw one line here that is worth knowing: third-party cookies are blocked by default in Incognito. That genuinely limits cross-site tracking within the session, and Google documents it as an Incognito default rather than a browser-wide one.

Matching the tool to the actual risk

If the risk is someone using your device, a private window is correct and sufficient. It is the use case the vendors put first themselves: Chrome’s help page offers a shared computer and shopping for a gift as its two examples.

If the risk is on the network, it does nothing whatsoever. Your provider, your employer’s network team and the sites themselves are all outside its reach, and no browser setting changes that.

If the risk is cross-site tracking, you get part of the way. Storage is separated and discarded, third-party cookies are blocked by default in Chrome, and Safari adds fingerprinting defences. Your fingerprint and your address still identify you to anyone collecting them.

Incognito mode is a well-built local storage control that works exactly as its makers describe. The gap has never been between what it does and what it claims. It is between what it claims and what people assume, and the fastest way to close that gap is to open a private window and check your own address in it.