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This paper consolidates research on web tracking by examining technical mechanisms, countermeasures, and regulations that shape the modern and rapidly evolving web tracking landscape. We synthesize fragmented literature across tracking techniques, defenses against tracking, and regulatory compliance. The field is experiencing transformative change due to industry shifts in advertising, browser adoption of anti-tracking features, and increased privacy regulation enforcement. We identify open research challenges and propose future directions for researchers, practitioners, and policymakers studying web tracking practices.

The Privacy chapter of the 2024 Web Almanac examines online tracking prevalence, privacy protection mechanisms, evasion techniques used by trackers, browser privacy policies, Privacy Sandbox proposals, and regulatory compliance across the web. This annual report provides data-driven insights into how privacy practices are evolving across the internet, analyzing millions of websites to understand the current state of web privacy.