What Is Third-Party Tracking and How Does It Follow You Across Websites
PB
Patrick Bushe
April 9, 2026 · 5 min read
Third-party tracking is when a company other than the website you're visiting records your visit. Because the same ad networks and analytics companies are embedded on thousands of sites, they can link your visits together into a profile of what you read, buy and search for.
How it works
- A news site loads a script, an ad or an invisible image (a "pixel") from an ad company.
- Your browser contacts that company, which reads or sets its own cookie: a third-party cookie.
- Later, a shopping site loads the same company's script. The company sees the same cookie and knows it's you.
- Over time, it builds a profile and uses it to target ads, or shares it with partners and data brokers.
This is why a product you looked at once follows you around in ads on other sites.
Tracking without cookies
- Fingerprinting: identifying your browser from its settings, fonts, screen and hardware. See device vs browser fingerprinting.
- Link decoration: IDs added to links you click, such as
?fbclid=or?gclid=. - Logins: signing in to the same account on many sites, or "Sign in with" buttons.
- Server-side tracking: the site sends your data to partners from its own server, out of the browser's view.
More detail in cookieless tracking methods.
Where browsers stand
- Safari and Firefox block third-party tracking cookies by default.
- Chrome still allows third-party cookies by default for most users. Google dropped its plan to phase them out, so blocking them is up to you.
How to cut most of it
- Block third-party cookies in Chrome: Settings → Privacy and security → Third-party cookies → Block third-party cookies. A few sites with embedded logins may need an exception.
- Use a tracker blocker to stop tracking scripts and pixels from loading at all.
- Reject cookie banners. Cookie Auto-Reject clicks "reject" for you, which also limits the cookies sites set for their partners.
- Turn off ad personalization in your Google account, and use separate browser profiles for work and personal browsing.
- Blur what's left. Ghost Browser visits random sites in the background, so the profile trackers build is less accurate.
To see which trackers a site uses, see how to check what data websites collect.
