Characterizing Browser Fingerprinting and its Mitigations

People are becoming increasingly concerned with their online privacy, especially with how advertising companies track them across websites (a practice called cross-site tracking), as reconstructing a user's browser history can reveal sensitive information. Recent legislation like the General Data Protection Regulation (GDPR) and the California Consumer Privacy Act have tried to limit the extent to which third parties perform cross-site tracking, and browsers have also made tracking more difficult by deprecating the most-common tracking mechanism: third-party cookies. However, online advertising companies continue to track users through other mechanisms that do not rely on cookies. This work explores one of these tracking techniques: browser fingerprinting. We detail how browser fingerprinting works, how prevalent it is, and what defenses can mitigate it.