What are web trackers?
Definition
A web tracker is code or a small file on a website or app that records what you do, such as which pages you visit, so advertisers and other companies can recognize you over time.
- Category
- Privacy
- Also called
- web trackers, website tracker, online tracker
- Last updated
Web trackers are how sites and ad companies recognize you from one page, and one site, to the next. The FTC explains that websites and apps collect information about you as you use them, and that companies use it to target ads and build profiles. The UK Information Commissioner's Office lists the main tools.
The main kinds
- Cookies are small text files saved on your device when you visit a site, so the site can recognize your device and remember your preferences. Third-party cookies are set by a domain other than the one you're visiting, usually through embedded ads, images or social media plugins.
- Tracking pixels (also called web beacons) are tiny images or code embedded in a page or email that report back when it loads. In email, they can record when you read it and roughly where you are.
- Link decoration puts a user ID in a web address so a second site can tell you're the same person.
- Device fingerprinting identifies you from your browser and device settings instead of stored files, so deleting cookies doesn't remove it.
- Mobile advertising IDs let apps and advertisers track you across apps on a phone.
Why it matters
One page view is harmless. Thousands add up to a profile of your interests, habits and location. The FTC notes that data brokers and ad networks can use cookies to compile and sell information about you. That profile can then end up in data broker records alongside your name and address.
Trackers vs. cookies
All cookies that follow you across sites are trackers, but not all trackers are cookies. Fingerprinting and pixels work without one.
How to protect yourself
- 1
Block third-party cookies and turn on tracking protection
Browsers now offer tracking protection and the option to block third-party cookies. Turn both on in your privacy settings.
- 2
Say no to optional cookies
When a banner asks, reject non-essential cookies instead of accepting all. See accept all cookies.
- 3
Reset or limit your phone's advertising ID
Your phone's privacy settings let you reset the advertising ID and limit ad tracking.
- 4
Add a tracker blocker, and know its limits
Ad blockers help but don't catch every tracker. Combine one with the browser settings above.
- 5
Remove the profiles trackers feed
Serus finds where your address and phone number are listed by data brokers and removes them.
See where your personal data is exposed
Serus finds it on data brokers and people-search sites and removes it.
Frequently asked
Are web trackers illegal?
Not by themselves. In the UK and EU, rules require consent for most cookies and similar tools. In the US it depends on the state and the data. That's why consent banners exist.
Can I stop websites tracking me completely?
Not completely. Browser settings, blockers and rejecting cookies cut most of it, but techniques like fingerprinting are harder to stop.
What is a tracking pixel in an email?
A tiny image that loads when you open the email and tells the sender you did, and in some cases when, roughly where and on what device. Turning off automatic image loading limits it.
Sources
- consumer.ftc.gov/articles/how-websites-and-apps-collect-and-use-your-information
- ico.org.uk/for-organisations/direct-marketing-and-privacy-and-electronic-communications/guidance-on-the-use-of-storage-and-access-technologies/what-are-storage-and-access-technologies/
- cisa.gov/resources-tools/training/follow-cybersecurity-best-practices-protect-yourself-tracking-technologies-and-spyware
Something wrong or out of date? Tell us and we'll re-check it.