Browser fingerprinting is a way to recognize a browser from its own characteristics rather than from anything stored on your device. A site runs a script that reads dozens of properties, combines them, and gets a value that tends to stay the same when you come back.
How is it different from cookies?
A cookie is a file a website asks your browser to keep, and you can delete it. A fingerprint is calculated from what your device already is, so there is nothing to delete. Clearing your browsing data or opening a private window usually leaves most of it unchanged.
What signals are used?
- Graphics: how your GPU and drivers draw canvas and WebGL content
- Audio: small numeric differences in how sound is processed
- Fonts: which fonts are installed and how text is measured
- Screen and hardware: resolution, pixel ratio, CPU core count and memory class
- Software: browser version, operating system, language and time zone
What is it used for?
Common uses are fraud prevention, bot detection, account security and advertising measurement. The same technique can serve to protect an account or to follow a person across sites, which is why it is regulated in some regions.
Can you reduce it?
- Keep your browser updated, so you look like many other users of the same version
- Use a browser with built-in fingerprinting protection
- Avoid unusual extensions and fonts, which make you stand out
- Treat tools that promise to make you invisible with caution: inconsistent values can make a browser easier to spot