Glossary
Browser fingerprinting
Browser fingerprinting identifies your browser — and often you — from the combination of its settings: screen size, language, timezone, installed fonts, and dozens of other details.
What it means
Browser fingerprinting identifies your browser — and often you — from the combination of its settings: screen size, language, timezone, installed fonts, and dozens of other details. No single detail identifies you, but the combination often can, like recognising a person from a description rather than a name. It works without cookies, which is why clearing cookies does not stop it. It is one of the main ways websites track people who never accepted a cookie.
How it works
A fingerprint is built from signals the browser shares freely with every site it visits: the user-agent string, screen resolution and colour depth, timezone and language, the list of installed fonts, the way the browser draws graphics on a canvas, and the features it supports. Each signal is unremarkable on its own; together they form a combination that is often unique or near-unique. The published figures for how many browsers are uniquely identifiable disagree wildly — roughly a third in one study, over 80 percent in another, over 90 percent in a third — because the studies used different methods, different years, and different definitions of unique. Our fingerprint demo shows what a site can read about your browser while creating no identifier, storing nothing and sending nothing anywhere: education, not identification, and the two must never be confused.
Example
Imagine a fictional user, Lena, who refuses all cookies and clears them daily, confident no site can track her. She visits two sites that both use fingerprinting: each reads the same combination of screen size, fonts, timezone and language, and each builds the same fingerprint. The two sites can now recognise her as the same visitor even though she never accepted a cookie on either one. Her cookie hygiene was real, but it addressed only one tracking method. The lesson is that tracking has more than one channel, and defending against one does not close the others.
Common misunderstandings
The most common misunderstanding is that fingerprinting is a single technique with a single number attached. It is a family of techniques, and the uniqueness figures depend entirely on how the study was done — which browsers were measured, when, and what counted as unique. Quoting one figure without its method is meaningless, and this site refuses to quote one as fact. The second misunderstanding is that there is a simple switch to stop it: there is not. Resisting fingerprinting means making your browser look like everyone else's, which is a trade-off with its own costs.
Related terms
Learn more
- What is browser fingerprinting?
- How do websites track you?
- How to check your digital footprint
- Internet Privacy Fundamentals
- Back to the full glossary
Last checked: 14 November 2026.
Frequently asked questions
Can I stop browser fingerprinting completely?
Not completely, and any tool that promises to is overselling. You can reduce it by using a browser designed to make every user look alike, and by limiting the signals you share — but the trade-off is real, and some sites will work less well.
Is fingerprinting illegal?
It depends on the country and on how it is done — in some jurisdictions it falls under the same rules as cookie tracking, requiring consent. The law here is still developing, and this is general information, not legal advice.
Does using private or incognito mode stop fingerprinting?
No. Private mode prevents your browser from saving history and cookies locally; it does not change the fingerprint your browser presents to websites. A site can fingerprint a private-mode browser just as it can a normal one.