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Background on how cookies and browser storage work, how trackers use them, and how browsers protect against that. Start with the basics, or jump to the feature pages for how each browser behaves today.

• Cookies, sites and contextWhat cookies and other browser storage are, how origins and sites differ, what first-party and third-party context mean, and how cross-site tracking works.
• PartitioningHow browsers keep a third party's cookies and storage separate for each site, shown with an interactive demo.
• How tracking protection worksHow browsers decide what counts as a tracker, and the difference between blocking a tracker and restricting its storage.
• Tracking techniquesThe techniques trackers use to follow people across sites, and how browsers respond to each.
• What this means for youHow browsers' tracking protections affect web development, analytics, advertising and experimentation, and what to do about it.
• Test your own siteHow to check what a browser does with your cookies and storage, using the browser's own tools and a few console commands.