Sometimes, the harder you work to stay private online, the easier it is for people to track you. That’s because of the phenomenon called browser fingerprinting. Here’s what it means, and how to deal with it.
When you visit websites, they collect information about your computer configuration. Some of this information is part of your Web browser’s user agent string, which you can change easily enough — although doing so is not always an ideal privacy solution, because some websites may not display correctly if the user agent string does not reflect your actual configuration.
And even if you do spoof your user agent, your browser still shares information with websites about the system fonts you have installed, which time zone you are connecting from and how large your screen is, for example.
This information forms what privacy advocates call your browser fingerprint. Sites can use the information to identify and track you.
The irony of browser fingerprinting is that people who take steps to protect their identity online tend to have unique browser fingerprints. If you run Windows and use Internet Explorer to browse the Web without privacy add-ons, you look the same to a website as hundreds of millions of other people on the Internet.
But if, for instance, you use a privacy-optimized Linux distribution like Tails, the tracks you leave behind you on the Web are a lot more unique, because your system’s configuration will stand out from the pack.
This doesn’t mean you should avoid installing tools that help protect your privacy, of course. But you should be aware of the issue, and should shy away from add-ons that don’t actually contribute to your privacy. Over-customization can undermine privacy.
Changing your browser settings periodically will also change your fingerprint and make you harder to track. Consider switching ad blockers once in a while, for example, or updating your system fonts.
If you’re curious what your browser fingerprint reveals about you, check out the Electronic Frontier Foundation’s Panoptoclick tool.