First introduced in Safari, Apple’s browser, and then in pretty much every other browser, private browsing looks like a magic option. Each browser has its own name for it: Incognito in Chrome, Private Browsing or a Private Window in Firefox and Safari, InPrivate in Edge. Different names, same basic idea, but not quite the same protections: Firefox, Safari and Chrome each add their own safeguards against online tracking.
Ever since Edward Snowden revealed how easily the NSA and many other intelligence agencies could watch us, most of us have had the feeling of being under a spy’s microscope.
On top of that, we’ve learned that most commercial websites identify their visitors so they can make the most of them every time they come back.
In short
- Private browsing only stops your browser from keeping traces on your device: history, cookies, form data.
- It doesn’t make you anonymous: websites, your employer, your internet provider and Google itself can still see what you do.
- It’s handy on someone else’s computer, to see a site as a logged-out visitor, or to keep a surprise secret.
- To hide your IP address or your location, you need a different tool, such as a VPN.
The magic button
Even if you have nothing to hide, it’s tempting to look for the app or option that lets you browse anonymously. You’ve heard that a friend of a friend found it. To browse safely out of reach of the NSA, the CIA or GCHQ, all you need to do is switch on private browsing or use the magic keyboard shortcut:
- Chrome or Microsoft Edge: Ctrl + Shift + N (on a Mac: Cmd + Shift + N)
- Firefox: Ctrl + Shift + P (on a Mac: Cmd + Shift + P)
- Safari on a Mac: Cmd + Shift + N
And there you are, safe from all those people. Magic, isn’t it? So… no more need for antivirus, anti-spyware or a firewall?
This is usually when a little voice shatters the illusion. It was too good to be true. Private browsing isn’t useless. But it’s a long way from making you invisible.
What is incognito mode?
Browser makers try to give this feature meaning with words like “private” and “incognito”. It’s not an easy task, because not everyone has the same idea of what a computer can do.
Calling a browsing session “private” gives the impression that it belongs to us. Like our home, where nobody gets to see who we let in.
“Incognito” means hiding your true identity. And incognito mode is just that: a way to cover your tracks while you browse. In practice, it mainly hides your browsing history, so that other people using the same device can’t see which websites you’ve visited.
Google itself learned the hard way that the name can be misleading. A class action filed in 2020 accused the company of collecting data on what users did in Chrome’s Incognito mode. To settle it, Google agreed in 2024 to destroy billions of data records and to update the message shown when you open an Incognito window, which now makes clear that Google may still see your activity. Private browsing hides your history; it doesn’t make you invisible. It’s important to understand its limits so you don’t get a false sense of security online.
What does private browsing actually do?
To understand what private browsing does, think about the role of your browser. It’s a program that interprets the data it receives from the network, following your instructions (clicks, addresses, searches, and so on).
To make browsing easier, it remembers the addresses of the pages you’ve visited and the cookies collected along the way. Those cookies can record that you’ve been on a site, or that you ticked “Remember me” the last time you logged in. To make future visits faster, it also keeps many images in its temporary files.
Browsers can also sync your browsing data across several devices. That’s handy now that we constantly switch between a computer and a smartphone. But to pick up where you left off on another device, your history has to leave your browser to land there.
The main job of private browsing is to limit what your browser keeps on your device. Modern browsers, as long as they are kept up to date, also block some trackers and dangerous sites, sometimes more strictly in private mode, but none of that makes you anonymous.
Someone watching your internet connection can usually see which services you connect to. But thanks to HTTPS (the padlock in the address bar), they normally can’t read the pages you open, what you type or your passwords. Spyware installed on your computer is a different story: it can see everything you do, private window or not.
And it’s not only criminal threats that private browsing can’t protect you from. Your company’s network, which all internet traffic at work goes through, can also log a great deal of what you do online, especially on a company computer. Private window or not. The same goes for your internet provider, who can see which sites you connect to. (On the other hand, if you use your own phone on mobile data, your traffic doesn’t go through your employer’s network, unless the phone is managed by your company.)
Computers and networks aren’t equally clear to everyone. So let’s look at a few examples where private browsing is useful, and others where it doesn’t help at all.
When is private browsing useful?
Based on what we now know, what is private browsing really good for?
There are some very specific uses for it. You may not be fully protected when you switch to private browsing, but at least you’re safe from a few embarrassing moments, and from causing trouble for your family and friends.
1. You’re using someone else’s computer
For one reason or another, you’re using a computer that isn’t yours. Are you going to delete the cookies, history and temporary files afterwards? It takes time, however little. And the owner may not appreciate losing their own cookies and history.
Private browsing takes care of it: when the session ends, the browser discards the history, cookies and temporary files it created. Close all your private windows, not just the one you were using, because they share the same session. Files you downloaded and bookmarks you added will stay on the computer, though. And on a computer you don’t control, private browsing can’t protect you from monitoring software or a keylogger.
2. You’re working on a site you’re logged in to
Another situation: you edit websites, blogs or forums. This is the one I come across most often (of course). I’m often logged in to my blog. To check that the page shows my latest changes, I open it in a private window. Since the browser doesn’t use the cookies from my usual session, I see roughly what a logged-out visitor sees, without having to log out. (Roughly, because a site can still vary with location, language or caching.)
3. You want to keep something to yourself
Is there something you’d rather hide from someone who uses the same computer? Say you’re shopping for your partner’s birthday present. Better not forget to cover your tracks. Private browsing does that for you without much thought: close all private windows and, hey presto, the browser has forgotten the session. (Just remember that the order confirmation may land in a shared inbox, and that targeted ads may still follow you on other devices if you’re signed in somewhere.)
When is private browsing no help at all?
The catch is that, even when private browsing is useful, it has its blind spots.
1. When you sign in to your accounts
This is the most common trap. If you sign in to your Google, Facebook or Amazon account in a private window, the site knows exactly who you are, and everything you do there is linked to your account. Private browsing only forgets your session once you close the window; it doesn’t stop the site from recording it in the meantime.
2. On travel websites
You’ve probably heard that travel sites raise the price when you search for the same flight or train a second or third time, and that private browsing helps you look like a new visitor. Good tip?
Not really, because the problem itself is largely a myth. Prices do change quickly, with demand, the number of seats left and how close the departure date is. But there is little convincing evidence that your own repeated searches push the price up. Skyscanner, for one, says neither repeated searches nor cookies affect the prices it shows. And back in 2014, an investigation by the French data protection and consumer authorities (CNIL and DGCCRF) found no sign of prices changing based on IP addresses or cookies.
Even if a site did want to recognise you, private browsing wouldn’t be enough: it can also rely on your account if you’re signed in, your IP address or the technical fingerprint of your browser.
A VPN replaces the IP address websites see with that of the VPN server. But that address isn’t necessarily different each time, and a site can still recognise you by other means. The most reliable way to find a good fare is still to compare several sites, set up price alerts and check the total price, luggage included.
3. On sites blocked in your country
Want to watch BBC iPlayer from outside the UK, or a show that isn’t available in your country? Your browser’s private mode won’t change a thing. It doesn’t change your IP address, and that’s what sites use to work out where you are.
You use an internet provider, and it makes no secret of the fact that you’re connecting through its network. So websites can easily work out your country, and sometimes your region or town, though not always accurately. The usual workaround is a VPN, which makes your connection appear to come from another country.
Even that doesn’t work with every streaming service. Many have found ways around it. The BBC, for example, tries to block VPN connections to iPlayer. Netflix also detects many VPNs and proxies: when it does, instead of showing the catalogue of the VPN server’s country, it may limit you to titles licensed worldwide.
Is it only about my browser?
No, and that’s just as well, because our online wanderings aren’t limited to browsers. Apps also collect information about what you watch and do. Several Google apps, such as YouTube and Google Maps, offer an incognito mode that works on a similar principle: what you search for or watch isn’t added to your account history. That doesn’t mean Google receives no data at all.
Which brings me to my question: what do you use private browsing for? Is that magic button still so appealing?
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