You have seen the banners and the settings toggles. "Accept all cookies" — which cookies? Why would a site set cookies from companies you have never visited? This article explains third-party cookies plainly, what they do, and why the biggest browsers are getting rid of them.
What is a "third party" in this context?
A cookie is a small text file a site stores in your browser. The "party" is the domain:
- First-party: the site you are actually visiting —
usefulorbit.comwhen you are on usefulorbit.com. - Third-party: a different domain embedded in that page — the analytics provider, video embed, or ad network serving the ad on the page.
A cookie set by an ad network when you visit any site is a third-party cookie, because from your point of view it comes from a third party to the site you are on.
How the tracking actually works
Every major ad network (Google, Meta, Amazon) runs scripts on thousands of sites. When you land on any of those sites, its script sets a cookie with a unique ID in your browser. The next site you visit that carries the same script checks for that cookie and recognizes the same ID.
Across a week of normal browsing, that single ID accumulates a trail: the shops you browsed, the articles you read, the searches you ran on that page. That trail is what "personalized ads" are built from — and it is assembled by the ad network, not by the sites you visited.
Why it became a problem
The tracking itself is not new. What changed is the scale and invisibility:
- Fewer, larger trackers: a handful of companies see a huge share of browsing.
- Cross-device joins: IDs get combined with logins and device graphs, so the trail follows you between phone and laptop.
- Surprising exposures: your health, politics, and location browsing can be reconstructed from ad-network profiles, then sold.
Regulators in the EU (GDPR), UK, and California (CCPA) pushed consent banners and right-to-know laws, but they did not ban the tracking model — they just required more disclosures. Browsers stepped in instead.
What browsers are doing about it
- Safari began blocking third-party cookies by default in 2017 (ITP).
- Firefox blocked them by default in 2019 (Enhanced Tracking Protection).
- Edge blocks them under Tracking prevention → Strict.
- Chrome has been phasing them out since 2024 (a series of plans and reversals; as of 2026 the default in most regions is blocking third-party cookies, with a per-site exception mechanism for sites that need them).
The result: third-party cookies are effectively dead as a tracking mechanism, and the advertising industry has moved to alternatives — first-party data, logged-in audiences, and techniques like fingerprinting (see Browser Fingerprinting: What Advertisers See).
How to control them yourself
Even if your browser blocks them by default, it is worth knowing the manual controls:
- Chrome: Settings → Privacy and security → Third-party cookies → Block third-party cookies. Per-site allow from the address-bar shield.
- Firefox: Settings → Privacy & Security → Enhanced Tracking Protection → Strict. "Cross-site cookies" are included in the block list.
- Edge: Settings → Privacy, search, and services → Tracking prevention → Strict.
- Opera: Settings → Privacy & Security → Cookies → Block third-party cookies.
The step-by-step versions for each browser are in Chrome Privacy Settings, Firefox Privacy Settings, Edge Privacy Settings, and Opera Privacy Settings.
What blocking third-party cookies does NOT do
This is where most people get confused:
- It does not stop first-party tracking. The sites you visit still know you logged in, what you read there, and what you searched on their site. First-party cookies remain.
- It does not stop fingerprinting. Trackers can identify your browser by its configuration (see the fingerprinting article).
- It does not stop log-in tracking. Ad networks you log into (or Google/Meta buttons you click) still see you across sites through that login.
Blocking third-party cookies removes the automatic, invisible cross-site trail. It does not make you anonymous.
Should you block them?
For most people, yes — the default-block setting in any modern browser is a reasonable choice. The trade-offs are small: some embedded maps/videos or legacy checkout flows need a per-site exception. If a site breaks, allow cookies for that site only rather than disabling the block globally.
FAQ
Are all third-party cookies trackers? No. Some are functional — a payment widget, a CDN, an embedded video player. That is why browsers give you per-site exceptions instead of an all-or-nothing switch.
Do I need to click "reject all" on every banner now? Blocking third-party cookies does not stop first-party tracking, and consent banners manage that separately. When a banner offers "Reject all," it is still the better choice for most sites.
Will sites work after cookies are blocked? The vast majority do. Sites that "require cookies" usually mean their own login and preferences, which are first-party and still work.
Is fingerprinting worse than cookies? In some ways yes, because you cannot delete a fingerprint like you can a cookie. Read Browser Fingerprinting for the honest picture and mitigation options.
Related reading
- Browser Privacy Guide: Lock Down Any Browser
- Incognito Mode Myths
- How to Check and Revoke Extension Permissions
- Spot and Avoid Online Scams
Sources
- Electronic Frontier Foundation — "The State of the Third-Party Cookie Phase-Out" (eff.org)
- IAB / industry references on the ad-tech shift to first-party data
- Browser vendor documentation: Apple ITP, Firefox ETP, Chrome third-party cookie phase-out pages
Last reviewed: August 2026.
---Written by Hassan Arshad, founder of UsefulOrbit. Last updated August 31, 2026.