Fingerprinting

Analytics & privacyDefined term

Fingerprinting derives a stable identifier from properties a device reveals incidentally: rendering quirks, fonts, screen and hardware characteristics, protocol details. Combined, these can be distinctive enough to re-identify a device with no cookie stored at all.

Because nothing is written client-side, deletion controls don't reset it — which is why standards bodies treat it as an abuse to mitigate rather than a feature, and browsers respond by reducing entropy: trimming APIs, coarsening values, and randomizing outputs.

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Analytics & privacy