Glossary
Device entropy
How much identifying information a device's reported properties carry — measured in bits, and lowered by looking ordinary rather than by hiding.
Also called: fingerprint entropy.
Entropy here is the information-theory sense: how much a value narrows down who you might be. A property shared by half the web carries one bit; a canvas hash almost nobody else produces carries twenty or more. Fingerprinting works by adding bits together — platform, language list, timezone, screen size, GPU strings, audio hash — until the combination points at one device. A handful of individually unremarkable properties can be conclusive together.
The counter-intuitive part, and the reason blocking is a poor strategy, is that refusing to answer usually raises your entropy rather than lowering it. A browser that reports no screen size is far rarer than one reporting an ordinary screen size, so the refusal itself becomes the identifier. The goal is to be unremarkable and internally consistent, not silent: a set of values that describes a plausible machine, generated together rather than scrambled field by field, since each independently random field is another chance for two of them to contradict. That is the argument in full on the fingerprints page.
More from the glossary
TLS fingerprint
An identifier computed from the way a client opens a TLS connection — the cipher suites, extensions and their order in the ClientHello.
Cookie injection
Writing a saved set of cookies into a fresh browser profile so it opens already signed in, without the password being entered.
Headless browser
A real browser engine run without a visible window, usually under automation. Cheap to run at volume, and increasingly easy for a site to spot.
CAPTCHA solving
Passing a challenge to a third-party service that answers it. Useful occasionally, and a poor substitute for not triggering the challenge.
Timezone and geolocation spoofing
Making a browser report a clock — and sometimes a position — that matches where the session claims to be rather than where the machine is.
Anti-detect browser
A browser built to run many separate identities on one machine, each with its own storage, device characteristics and network address.
Every entry is listed on the glossary index.