What Is Link Decoration Tracking and Why Google and Meta Use It

Link decoration means adding extra information to the end of a web address, usually after a ?. Some of it is harmless, such as page numbers or search terms. Some of it is a unique ID that lets an ad platform connect your click to what you do next.

Common tracking parameters

• fbclid: added by Facebook to outbound links since 2018.
• gclid: added by Google Ads when you click an ad.
• msclkid: Microsoft Advertising's click ID.
• ttclid: TikTok's click ID.
• utm_ tags, such as utm_source and utm_campaign: campaign labels that tell a site where visitors came from, usually the same for everyone who clicks.

The first group are unique to each click; UTM tags usually aren't.

How click IDs track you

1. You click an ad or a link on a social platform. The platform adds a unique click ID to the address.
2. The site you land on reads the ID and stores it, often in a first-party cookie.
3. When you sign up or buy, the site sends the ID back to the ad platform, sometimes from its own server.
4. The platform matches it to your click, and knows that its ad led to your purchase.

Why it became popular

Third-party cookies are blocked by Safari and Firefox. A click ID in the address travels with you to the new site, where it's stored as a first-party cookie, so it works without third-party cookies. See first- and third-party cookies and conversion APIs.

What browsers do about it

• Safari limits how long cookies set after some decorated links last, and since 2023 removes known tracking parameters in Private Browsing, Mail and Messages.
• Firefox strips known tracking parameters in strict tracking protection and private windows, and its right-click menu can copy a link without them.
• Brave removes many tracking parameters by default.
• Chrome doesn't strip them by default.

How to share clean links

• Before sharing, delete everything from ?fbclid= or ?gclid= onward. Test the shortened link still works; some sites need part of what follows the ?.
• Use Firefox's clean-link copy option, or an extension such as ClearURLs in Chrome.

Reduce tracking more broadly

• Reject non-essential cookies, so sites store less.
• Turn off personalized ads in your Google and Meta accounts.
• Ghost Browser makes random background visits, so the interest profile built from your browsing is less accurate.

See how retargeting works.