When browsing the web, your browser fingerprint lets sites identify you as a unique user. It uses information like your device’s screen resolution, installed fonts, and plugins, your operating system, the time zone, and your language settings to create a distinctive profile that’s unique to you. This profile is used to track you on websites that use fingerprinting, even when you’re logged out or using incognito mode. It’s also used to target ads and enhance security through identity verification.

Fingerprinting has been around for a while, but its usage is rising rapidly. Research from 2020 found that a quarter of the top 10,000 websites ran fingerprinting scripts. It’s often used to get around cookies, and it can track you even when your IP address is secured by a VPN or other tool.

Web Fingerprinting: Understanding User Identification Online

Web fingerprinting can be extremely accurate. A website may render a hidden canvas element and measure the output; slight variations in rendering due to your graphics hardware and installed fonts will yield a distinct fingerprint. A site may also use audio fingerprinting by generating an inaudible sound, the processing of which varies between devices, to create a distinct profile.

Some techniques can be abused by fraudsters, and they are often used to associate people with malicious activities, like spamming or phishing. However, the ability to reliably and quickly identifies users without the need for easily concealed identifiers, like cookies or IP addresses, makes fingerprinting useful to many legitimate businesses.