Websites use browser fingerprinting to capture information like browser type, OS, active plugins, time zone, and a variety of other active settings to track online user behaviour.

The uniqueness of the combination of settings is why it is referred to as “fingerprinting”. Your browser fingerprint is saved when you visit a site and used to specifically target you when you return.

While it doesn’t explicitly reveal who you are, it is incredibly useful for retargeting you for advertising. This type of fingerprinting is also used to help identify botnets to prevent fraud, and is specifically used by banks to identify cases of potential fraud.