Online marketers have always wanted to track you. They once relied on cookies— little digital notes they left on your device so they could know who you were each time they saw you. But over time, software and people have made cookies a less useful tool.
So they evolved. They developed new methods.
One of the most devious and pernicious is called ‘fingerprinting’, in which a marketer, website, or advertiser figures out who you are based on the set of configurations you use on your computer—your system fonts, your resolution setting, your software versions, etc. It turns out when you collect enough of these attributes, there are few—if any—people who are exactly the same as you. So they know you by your configuration ‘fingerprint’.
Advertising networks use this fingerprint to identify you and link you to the huge profiles they’ve been building about you while you use the internet. So when you log into a site, they can look up how much money you make, what kinds of products you’ve bought in the past, who your friends are, etc.
With all this information, they decide which advertisers are willing to pay the most to put something in front of you. For many of us, that’s a bad thing, but the technique actually has two major applications. While on the one hand ads can track you, on the other hand, security experts can use fingerprints to identify computers used in an attack.
What elements are being used on your computer to create your fingerprint? You can actually find out by checking out the Electronic Frontier Foundation’s Panopticlick.
The EFF’s results will typically show data that the browser can’t help expose since the data is part of how the browser itself interacts with the web.
A recent report revealed that nearly half of America’s top 500 trafficked sites—including CNN, BestBuy, WebMD, and a variety of porn sites—use some form of browser fingerprinting.