Guides
Browser privacy guide: cookies, storage, fingerprinting, permissions, history, extensions, and profiles
A browser privacy guide to cookies, site storage, fingerprinting, permissions, history, autofill, extensions, and profiles, with checks you can run.
What to take away
- A browser holds six separate stores of your activity, and no single button clears all six.
- Clearing history does not touch the account record the site keeps on its own servers.
- Cookies do real worksession cookies hold your login, and blocking them all breaks sign-in.
- Fingerprinting survives a cookie wipe because it reads your device, not your stored files.
- Site permissions and extension permissions are two different lists, reviewed in two places.
- A private window limits local traces; it does not make you anonymous to the site or the network.
The six layers in one browser
A browser sits between you, the device, the sites you open, the extensions you installed, and any account you signed in to. Each privacy control covers one layer and leaves the others alone.
Six Browser Privacy Layers
Layer
- Page activity
- Addresses, searches, downloads, forms
- Site state
- Cookies, local storage, IndexedDB
- Device access
- Camera, microphone, location, clipboard
- Browser features
- History, autofill, passwords, profiles
- Extensions
- Added code and its permissions
- Sync and accounts
- Copies elsewhere via browser or site
What It Covers
- Page activity
- Site state, device access
- Site state
- Fingerprinting, signed-in identity
- Device access
- Site state, browser features
- Browser features
- Site state, sync
- Extensions
- Site state, browser features
- Sync and accounts
- Local clearing
Clearing It Does Not Fix
- Page activity
- Site state
- Device access
- Browser features
- Extensions
- Sync and accounts
The six layers
- Page activity:addresses, searches, downloads, form entries, media played.
- Site state:cookies, local storage, IndexedDB, cached files, service workers.
- Device access:camera, microphone, location, notifications, clipboard, sensors.
- Browser features:history, autofill, saved passwords, payment details, downloads, profiles.
- Extensions:the code you added and the permissions it holds.
- Sync and accounts:what your browser account or a site account copies elsewhere.
You can clear your history and still be signed in. You can block third-party cookies and still be tracked by the shape of your device.
Cookies and what else a site stores
A cookie is a small item a server sends to your browser, which stores it and returns it with later requests. Session cookies hold your login. Preference cookies remember a language or a layout. Tracking cookies carry an identifier.
Cookies vs Other Site Storage
Storage Type
- Cookies
- Yes
- Local storage
- No
- IndexedDB
- No
- Service workers
- No
Travels With Requests
- Cookies
- Yes
- Local storage
- No
- IndexedDB
- No
- Service workers
- No
Cleared With Cookies
- Cookies
- Local storage
- IndexedDB
- Service workers
MDN's guide to HTTP cookies covers several topics:
Cookies and site storage
- session management
- personalization
- tracking
- expiry
- the Secure, HttpOnly and SameSite attributes Read it before you decide a cookie is harmless or hostile.
Local storage, IndexedDB and service workers hold larger data and never travel with a request. Clearing cookies can leave them behind.
First-party and third-party describe which site set the cookie, not how sensitive it is. A first-party session cookie can guard your bank account. A third-party script can be the payment form you need.
Tracking and fingerprinting
Tracking links your activity across time, pages, sites, devices or services. It can use cookies, link parameters, embedded images, or a signed-in identity. It can also use an advertising ID or server-side records.
Fingerprinting reads your device instead. It checks browser version, screen size, language, and installed fonts. It also checks graphics behavior and timing. Clearing cookies does not reset those traits, because nothing was stored on your machine to clear.
Anti-fingerprinting works by making many users look alike. A browser with unusual custom settings can stand out more than a default one.
Permissions, site by site
A site can ask for your location, camera, microphone, notifications and clipboard. A granted permission is a standing capability, not proof the site used it.
Permission Prompt Decision
Does the page work without this permission?
Deny the permission
Decide if the feature is worth the access
Open your browser's site settings and sort by permission rather than by site. Revoke anything stale. Where the browser offers "allow this time" or "while using", prefer it over "allow".
Do not grant a permission just to dismiss a prompt. If the page works without it, deny. If it breaks, decide whether the feature is worth the access.
History, downloads, autofill, and the traces beside them
Browser history lists addresses you visited. Download history is often only a list; deleting it does not delete the files. Autofill can hold names, addresses, payment details and form entries.
Clipboard managers, screenshots, and your operating system's recent-files list keep separate copies. Clearing the browser leaves those in place.
Before you clear anything, name what you need to keep. Removing cookies signs you out. Removing saved passwords without a working replacement can lock you out of an account. Clearing a cache fixes a display problem and erases no purchase record.
Extensions
An extension can block ads, manage passwords, change how pages render, or add a tool you use daily. Its permissions may let it read and change data on every site, manage downloads, inspect tabs, or read your history.
Check the publisher, where you installed it from, the permissions it requests, when it last updated, and whether the browser now does the same job. Remove anything abandoned or unexplained. A trustworthy developer does not make broad permissions necessary.
Profiles, guest mode, and private windows
Profiles separate bookmarks, history, extensions and signed-in accounts, in varying degrees by browser. They are good workflow barriers for work, shopping, testing, or a shared household machine.
They are not a security boundary. When two people must not reach each other's local data, use separate operating-system accounts.
Guest and private windows limit what stays on the device after the window closes. Your employer, your school, your network operator, the sites themselves, and any downloaded file can still record what happened.
A baseline you can actually keep
A baseline you can keep
- Update the browser and the operating system.
- Use one supported browser for daily work, with separate profiles where mixing causes risk.
- Turn on the browser's built-in cross-site tracking control.
- Review site data and permissions quarterly, and again after a sensitive task.
- Remove extensions you no longer use.
- Protect browser sync with strong authentication and a recovery method you control.
- Lock the device, and give each person a separate system account.
- Re-test the sites you rely on after tightening anything, and add narrow exceptions only where a site genuinely fails.
For the settings themselves, work through tightening browser privacy settings in order, one layer at a time.
Browser Privacy Baseline
- Update browser and operating system
- Use separate profiles where mixing causes risk
- Turn on cross-site tracking control
- Review site data and permissions quarterly
- Remove unused extensions
- Protect sync with strong authentication
- Lock device and use separate system accounts
Common questions
Does blocking all cookies give the best privacy?
It reduces stored data and breaks sign-in, carts, preferences and embedded payment or media. Most people get further by blocking third-party cookies and reviewing site data by hand. Test the sites you depend on before you commit.
Does HTTPS stop tracking?
No. HTTPS encrypts data between your browser and the server. The site still receives your request and can record it, and the page can still load third-party resources.
Is a private window anonymous?
No. It mainly changes what stays on your device after the window closes. Sites, signed-in accounts, your network, and device software can still identify or observe the session.
Should each family member use a separate browser profile?
Profiles stop accidental mixing of bookmarks, history and logins, which is usually enough on a shared machine. When people must not reach one another's files or saved passwords, separate operating-system accounts are the stronger separation.
In this guide
- How to review and tighten browser privacy settingsA browser privacy review that audits permissions, cookies, extensions and sync, then tests the sites you rely on before trusting the changes.
- Browser tracking methods compared: cookies, local storage, fingerprinting and pixelsBrowser storage and tracking methods compared by source, persistence, transmission, cross-site reach, deletion, common uses, privacy limits, and control options.
- Browser cookies, site data, permissions, history, autofill, extensions, profiles, and update checklistBrowser privacy checklist for versions, profiles, sync, cookies, storage, permissions, history, autofill, downloads, extensions, tests, and exceptions.
- Browser privacy problems: persistent sign-ins, tracking, risky extensions and fingerprintingBrowser privacy problems traced through symptoms, checks, fixes, and limits for sessions, tracking, extensions, saved secrets, permissions, and fingerprints.
- Separating work, shopping, and personal browsing in a shared laptop caseFictional shared laptop case separating work, shopping, and personal browsing through device accounts, profiles, sync, permissions, extensions, and cleanup.
