What the feature is
Most browsers offer a mode that opens a separate window with different rules about what is kept. It goes by several names: Incognito, Private Window, InPrivate, or Private Browsing. The details differ between browsers, but the idea is the same. The window starts with no record of your normal session, and when you close it, the browser discards what that session created.
The key word is “browser.” The mode affects what your browser keeps on your device. It does not change what the internet can see.
What it forgets
When you close all private windows, the browser typically deletes:
- Browsing history for pages visited in that window.
- Cookies and site data created during the session. Sites loaded in a private window start without your existing cookies, so you usually appear signed out, and anything stored during the session vanishes at the end.
- Form entries and search suggestions typed in that window.
- Temporary files such as cached page elements.
Most browsers also avoid saving passwords and autofill details in this mode, or ask before doing so. Some block certain third-party trackers by default, but this varies, so check your browser’s description of the mode rather than assuming.
Anything you deliberately keep stays. Files you download remain on your device, and bookmarks you save remain in your bookmarks. Those are your choices, not session leftovers.
What it does not hide
This is where misunderstandings arise. During a private session, other parties can still see your activity.
The websites you visit. A site sees your visit, your IP address and technical details about your browser regardless of mode. If you sign in to an account, the site knows who you are for the rest of that visit.
Your internet provider. The company supplying your connection can generally see which domains your device contacts, even though page contents are normally encrypted on secure sites. How domain lookups work is explained in the article on the domain name system.
Your employer, school or network owner. Managed networks and devices may log traffic or run monitoring software. Private windows do nothing about that.
Your device itself. Software that records keystrokes or screens, whether legitimate or malicious, is not stopped by private mode. Browser extensions may also be allowed to run in private windows if you permit it.
Advertisers and trackers during the session. Trackers can still follow what you do within a single private window. They simply lose the link to your normal browsing once the window closes. A fuller picture of how that following works is in the article on tracking cookies.
Traces outside the browser. Network equipment, such as a home wireless router, can keep logs of devices and connections. Domain lookups can be cached by the operating system for a short time. Both are separate from the browser.
Fingerprinting. Sites can sometimes recognise a browser by its combination of screen size, fonts and settings, which persists across normal and private windows. Browsers increasingly try to reduce this, with varying success.
Common misconceptions
- “It makes me anonymous.” It does not. It limits what is saved locally.
- “It blocks tracking completely.” It limits tracking across sessions, not within one.
- “It protects me on public Wi-Fi.” Private mode does not secure the connection. Secure websites encrypt traffic, but a private window adds no protection on top of that, so the cautions in the article on public Wi-Fi still apply.
- “It hides my activity from my provider or boss.” It does not.
- “It’s a safe way to shop for better prices.” Some people use it to avoid personalised pricing, but whether a site adjusts prices by browsing history differs between businesses, and a private window will not necessarily change the result.
Where a stronger layer is wanted, a virtual private network changes what your provider and local network see, although it brings its own trust trade-offs and still does not stop a site from knowing you after you log in.
When it is useful
Private windows are good for local, practical tasks:
- Using a shared or borrowed computer, so that your sign-in and history are not left behind. Remember to close all private windows and sign out of anything you opened.
- Planning a surprise, such as a gift, so that suggestions do not show up in the family computer’s search history.
- Checking how a page looks when signed out, or testing a site without existing cookies.
- Signing in to a second account at the same time as your first.
- Looking something up that you do not want to influence your suggested content or recommendations in future.
Getting more privacy from the browser itself
If your goal is less tracking in general, normal browser settings usually make a bigger difference than private windows. Blocking third-party cookies, using the tracking protection mode and clearing data on exit are covered in the article on browser privacy. Some browsers also offer extra protection in private windows, so look at the privacy page for what your browser actually does.
A realistic summary
Private mode is a tidy-up tool: it leaves your device free of a session’s history. It is not an invisibility cloak. Use it for local privacy from people who share your device, and rely on other tools and habits for anything involving websites, networks or companies.