Privacy Badger is a free browser extension developed by the Electronic Frontier Foundation (EFF) that blocks advertisers and third-party trackers from secretly tracking users' online activities. It works by analyzing and blocking trackers that violate user consent, and it also sends signals to companies to opt out of data sharing and selling. The extension is designed to incentivize advertisers to adopt better privacy practices and to provide users with more control over their online data. By using Privacy Badger, users support the EFF and contribute to the fight for a better internet.