Device fingerprinting is a technique used to collect unique information about a user's device, such as browser type, operating system, screen resolution, and installed fonts. By combining these details, websites or applications can create a distinctive 'fingerprint' that identifies and tracks individual devices across sessions, even if cookies are disabled. This method is often used for fraud prevention, targeted advertising, and sometimes for bypassing security measures. While it can enhance user experience and security, it also raises privacy concerns as it enables persistent tracking without user consent.