What Is a Tracker?

In previous articles, I have given you tips on how to avoid and block trackers. But what are these things, and how do they work? In this article, I will outline how trackers work and what threat they pose to your privacy.

Trackers are scripts and pixels deployed by comapnies to obtain your data. They can have many purposes, from targeting advertisements to obtaining data to sell. These trackers obtain information from your browser or device in order to determine your identity. When they use your browser, they usually deploy a cookie or similar script to read your browser's unique identifiers. Browsers combat this by blocking third party cookies and scripts from known trackers, and by obfuscating identifiers so that trackers can't tell you apart. When the trackers are targeting your device, this is called fingerprinting, and it is harder to stop. The best way to stop fingerprinting is to make all browsers and devices look the same. This is done by obfuscating your device's identifiers, and making all users look the same. For example, Safari combats fingerprinting by making all copies of the browser look the same and blockng access to device identifiers like OS version and technical specifications. These identifiers allow trackers to connect data they obtain with a profile of your browsing habits. 

But what is in this profile? Trackers can log all kinds of data, like the sites you visit, how long you spend on those sites, and what you do on those sites. They do this by a variety of methods. Trackers know what website they are deployed on, so when they see you on the site, they can determine your browsing history by adding the site to your profile. Some trackers log what you do on sites by recording your session. This records mouse position, text entered into fields, things you click on, and how long you spend on the site. These trackers are especially dangerous because they can reveal personal information like usernames, passwords, credit card numbers, bank PINs, and adresses. Other tracers measure your clicks by being embedded in buttons and other interactives on the site. When the button is clicked, the tracker registers this and adds it to your profile. Other interactives involve third party content, like an embedded social media post or YouTube video. These are called iframes, and they can have trackers as well. Iframes can track what you do in them, but many iframes can also track you on the webpage they are embedded in.

Companies use the profiles that trackers generate for many purposes. The most common use of this data is to increase revenue. This can be done by targeting ads or by selling the data. Companies usually buy your data to target ads, but it could also be used nefariously to hack you or steal your passwords. Ad targeting is also bad, because when your data is in the company's servers, it can be leaked if the company has a data breach, allowing hackers to access your data. Some companies don't even encrypt the data that they are storing, making it easy for anyone to read. Having your data in more places than it needs to be is dangerous because it significantly increases your risk of hacking. The worst thing about it is that these companies don't need the extra revenue. For example, Google targets its ads so that advertisers will pay more for ad space, but Google could still make the majority of its profits only using contextual advertising, which respects privacy.

These trackers are a major privacy risk, but there are ways to get rid of them. Secure DNS services like NextDNS block known trackers from communicating with their servers to prevent them from adding data to your profile. Browsers like Brave and Safari detect tracking scripts and stop them from loading on your device. Search engines like DuckDuckGo and Startpage do not have trackers to begin with. Using these services instead of non-private ones like Google and Google Chrome is the best defence against trackers. If you want more protection, use the Tor network or a VPN to hide your web activity from hackers and trackers, or use a blocking extension like Ghostery to furter reduce tracking. If you want to learn more about trackers, check out the resources on this website or visit whotracks.me.