A comprehensive look at how third-party cookies went from an accidental innovation solving e-commerce problems to the surveillance backbone of the internet, and why regulators, browsers, and users finally killed them. Covers Lou Montulli's original invention, the advertising industry's pivot to behavioral tracking, the regulatory reckoning (GDPR, CCPA), Google's paradoxical elimination of their own profit center, and what actually changed in the post-cookie world. Includes perspective from industry leaders on how this shift redistributed power among tech platforms.