How They Know Who You Are

What is browser fingerprinting?

As the name suggests, browser fingerprinting is a fingerprint of your browser. This means that there is a unique ID that can be used to identify you and your computer.

HTML, CSS, and Javascript are the languages used to create websites. Javascript is a very powerful language used in web pages. It allows the websites to be more interactive, but this also means that it needs information to optimize your experience. Javascript can know things like the resolution of your screen, your computer hardware or whether you are navigating through a website using your phone, and the orientation of your phone. This is very useful to provide a great user experience, but here is also where it starts getting more complicated. Javascript can know what web browser you use, your device type, your time zone, the default language of your browser, what apps or plugins you have, and more.

How is this done?

There are several tests that can be run on your screen to get information about you. For example, with javascript you will draw a box off the viewport, where javascript will code a couple of letters. This is known as a font test. This matters because each computer renders text differently, for example your computer might have a different graphic card than mine. This gives the website unique information about your device. This is a pretty common test, and sometimes the test could be run such that it will create a graphic design rather than letters to identify your computer. There are other tests that exist out there such as the canvas test.

However, as you can infer, most information is basic and it is not very helpful for it tells very few basic facts about you and your computer. But, when websites have a long list of basic information, they can assemble it together and form a more concrete identifier for you.All of this information generates a unique code and this is sent to the website’s server.

What does this mean for my privacy?

If you are on a website that uses browser fingerprinting then you are probably not as “private” as you think you are. You can be logged out, in private browser mode, and they can still track you. Websites like https://panopticlick.eff.org/ can offer you a demonstration of how browser fingerprinting works on your device so you can learn about how “protected” you are.

How about cookies?

Another common tool used to collect information about us is called “cookies”. A term we see often while browsing through the internet. Cookies are files placed in your computer by your browser.

Types of Cookies:

Session Cookies: These type of cookies allow you to move from one page to another in the website without the need to log in every time you move to another page. So when you are done navigating through the website, the cookie gets deleted as you log out the website.

Persistent cookies: These stay in your computer and keep track of the sites you have visited.

As you can see there are multiple ways to obtain a variety of pieces of information about you. Even a website's web server is able to understand your IP address. (if you use a VPN this might not apply).

With all this information put together...

Let's think about what can be known about us then: gender, personal status, your age, what music you listen to and what tv shows you watch, what city you live in, what websites you like to visit and what you like to buy online. Even your behavior can be monitored!

But why would they want to know so much, and who benefits from this information?

Companies who are trying to sell you something can use the information about you to target products that you might want to buy. This information can also be used to show you advertisements of products that you already looked up on the internet or that you might be interested in. But other bigger companies can also benefit from this information, like: banks, insurers, and landlords. Most of the times, your information is being sold to these companies.