Browser fingerprinting is a tracking technique that identifies users by collecting unique combinations of browser and device attributes — including screen resolution, installed fonts, browser version, timezone, language settings, and hardware configuration. Unlike cookies, fingerprinting does not store data on the user's device and cannot be removed by clearing cookies, making it persistent and difficult to avoid. Under GDPR and the ePrivacy Directive, fingerprinting that accesses device information or processes personal data requires the same explicit consent as cookies. Data protection authorities including the CNIL and the ICO have ruled fingerprinting-based tracking without consent is unlawful.