Even going incognito can't save you.
Every person's internet activity is unique. To better tailor an experience to user preferences, websites track user activity using cookies. But what people like about the internet is that it affords a great deal of anonymity, prompting the development of anti-tracking systems to stop cookies in their tracks. Unfortunately, canvas fingerprinting doesn't use cookies. In fact, it was designed as a cookie alternative, so anti-tracking systems currently available can't do anything to block it.
What is canvas fingerprinting in the first place?
Canvas fingerprinting happens when your web browser generates a specific image representing you. Web browsers create images differently so it is possible to assign a number to a "fingerprint" to identify it. Much like your own fingerprint, the image created by your web browser is unique. With it, it brings everything you've done on your browser, creating a profile for you. Theoretically, the profile will then be used to create a more customized web experience for you, affecting which ads, articles, news and other kinds of content will be displayed while you are online.
There is merit in wanting users to have an online experience that will suit them perfectly, but many would rather deal with generic content than have someone (or something) hovering over their every move.
AddThis, a social-bookmarking service provider, is believed to be the first to actually use canvas fingerprinting to track customer internet activity for its clients but is not its original author. Instead, AddThis simply improved upon a code that Valentin Vasilyev, a Russian programmer, released online, which he made by adding the canvas feature to an already-freely-available fingerprint code.
Research done by a group from Princeton University and Belguim's KU Leuven University shows that five percent of the top 100,000 sites today employ canvas fingerprinting. As of May 5, 2014, there are more than 5,600 sites identified to be using canvas fingerprinting, including YouPorn, CBS Local, Perez Hilton and the White House. These sites don't all use AddThis though. Other known canvas fingerprinters include Ligatus, a German digital marketer, and Plentyoffish, a Canadian dating site.
Rich Harris, CEO for AddThis, has said that the data the company collects from canvas fingerprints are only used for internal development and research. Arvind Narayanan, one of the researchers, countered that taking AddThis' word on how data is used is not very reassuring.
The good news is that canvas fingerprinting can be thwarted. The bad news is that available methods at the moment will either completely ruin web browsing experience or will require above-average technical know-how.
