What is browser fingerprinting, and why does it defeat IP masking?

Fingerprinting builds a near-unique identifier from your browser's configuration, so a site can recognise you even with a hidden or rotating IP.

Even if a VPN or proxy masks your IP address, your browser leaks dozens of small details that combine into a distinctive "fingerprint":

• Screen resolution and colour depth
• Installed fonts and plugins
• Browser version and operating system
• Time zone and language settings
• Canvas and WebGL rendering — how your specific GPU/driver draws a hidden image

No single attribute identifies you, but the combination is often unique among millions of users — like how a set of ordinary traits together pinpoints one person. Because fingerprinting reads passively exposed properties, it needs no cookies and no stored state, which is exactly why clearing cookies or changing IP doesn't stop it.

Tip: Try it yourself at coveryourtracks.eff.org or amiunique.org — you'll likely find your browser is one-in-a-million.

Go deeper:

• Device fingerprint (Wikipedia) — canvas/WebGL/font attributes that form a stateless identifier needing no cookies.
• Cover Your Tracks (EFF) — measures how unique your own browser fingerprint is.