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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Choose a Classic window for everyday browsing and sessions you want Firefox to remember, a Private Window when you want Firefox to discard that session’s history and cookies after it closes, and Smart Window when you want AI help and are comfortable sharing the context you select. They serve different purposes: Private Browsing does not make you anonymous, while Smart Window is not a guarantee of correct answers.
Which Firefox window fits your task?
| Your need | Best fit | Why |
|---|---|---|
| Everyday browsing, saved sign-ins, and history you want to revisit | Classic window | Firefox retains the usual browsing history and site sessions. Tracking protection is available here too. |
| A session you do not want left in Firefox history or cookies afterward | Private Window | Firefox removes the session’s history, cookies, and site data after the last Private Window closes. |
| Separate work and personal accounts on the same website | Classic window with Multi-Account Containers | Containers keep site data distinct by tab context and can keep multiple accounts signed in. They are disabled in Private Windows. |
| AI assistance with a task or page | Smart Window, if available and suitable | It uses an AI assistant that may consider page or tab context you reference. Check what you are sharing and the applicable terms and settings. |
Mozilla’s documentation explains the specific behavior of Private Windows, Multi-Account Containers, and Smart Window.
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What Classic windows keep—and what protection they still have
A Classic window is Firefox’s ordinary browsing mode. History, cookies, and site data remain available as usual, which helps preserve sign-ins and lets you return to pages through history. Choose it when continuity matters more than clearing the session’s local data automatically.
Classic does not mean unprotected. Firefox’s Enhanced Tracking Protection (ETP) is separate from the choice between Classic and Private windows. In the desktop documentation, Standard mode confines cookies by site and limits tracking-content blocking to Private Windows; Strict mode extends blocking to all windows and includes bounce-tracking protection. Settings and exact behavior can change, so consult Mozilla’s current ETP documentation for the options in your version.
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What a Private Window does—and does not—keep
Firefox says it deletes browsing history, cookies, and site data from a private session when all Private Windows are closed. If several Private Windows are open, closing just one does not end the session; the cleanup occurs after the last one closes. This can be useful on a shared device, for a fresh session with a site, or when you do not want a lookup saved in Firefox history.
Some things remain on the device
- Files you download remain on the device, even though private-session downloads are not kept in Firefox’s Downloads list after the session.
- Bookmarks you create remain saved.
- Signing in still identifies you to the site. Private Browsing does not undo what you tell a website.
Mozilla’s Private Browsing guide describes these session limits and how to use the feature.
Private does not mean anonymous or immune to monitoring
Private Browsing mainly changes what Firefox retains locally after the session. Websites and search engines, your internet provider, and an employer or school network may still observe activity; Private Windows do not hide your IP address or location. They are also not a security sandbox: they do not protect against spyware or keyloggers on the device.
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A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Firefox says Enhanced Tracking Protection blocks known trackers and Total Cookie Protection prevents a tracker on one site from seeing activity on another. Firefox blocks companies whose business is fingerprinting in every window and hides additional identifying details in Private Windows. Private Windows also send Global Privacy Control, but whether a site honors that request depends on the site and applicable law. These protections reduce some tracking; they do not make browsing invisible. See Mozilla’s explanation of what Private Windows protect.
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Why ads can still appear in Private Windows
Blocking trackers is not the same as blocking every ad. Ads may be contextual, or related to an account you are signed into, so seeing an ad does not by itself mean Private Browsing failed.
Use Containers when you need separate accounts
If you want to keep work and personal accounts signed in at the same time, Multi-Account Containers are a better fit than repeatedly opening Private Windows. A container keeps a site’s data—such as its cookies—separate from that site in another container, so you can use distinct account contexts in tabs within a Classic window. Mozilla describes color-coded contexts such as Work, Banking, Shopping, and Personal in its Containers guide.
Containers are about organizing and separating site sessions, not removing browsing activity when you close a window. They are disabled in Private Browsing windows, so choose a Classic window for this setup.
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When Smart Window makes sense
Smart Window is for tasks where you want help from an AI assistant, potentially using the current page, open tabs you reference, or history you explicitly ask about. Mozilla says Private Window activity is inaccessible to Smart Window. Because page and tab context can contain sensitive information, consider the content before asking for help and review the feature’s terms and settings.
Availability and privacy details
Smart Window availability depends on rollout and region, not just whether you want to use it. Mozilla’s safety page says rollout starts in the US and Canada with Firefox 150 and in France with Firefox 155; it does not establish universal availability. Check Mozilla’s current getting-started guide for availability and use in your location.
Mozilla says requests pass through a proxy, so the AI service does not see the user’s unique Firefox/browser identifier or IP address. Conversations are not collected or stored for training or human review unless the user opts in. Those protections do not remove the need to choose carefully what context to share.
Treat AI answers as assistance, not authority
LLMs can produce incorrect or misleading information. Mozilla describes safeguards but warns that harmful outcomes cannot be completely prevented. Verify important claims—especially decisions involving health, safety, money, or legal obligations—against reliable sources rather than relying on an AI response alone. Read Mozilla’s Smart Window safety and privacy information before using it with sensitive material.
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Quick Recap
A quick choice checklist
- Want normal history, saved sign-ins, and continuity? Use a Classic window.
- Want Firefox to discard session history, cookies, and site data after browsing? Use a Private Window, then close all Private Windows.
- Need separate signed-in accounts for the same site? Use Multi-Account Containers in a Classic window.
- Want AI help and can safely share the relevant context? Use Smart Window if it is available in your region and version.
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