GCLID
Also called Google Click Identifier.
The identifier Google appends to your landing page URL when someone arrives from an ad and auto-tagging is on. Capturing it and storing it with the lead is what lets a deal recorded months later be joined back to the click that caused it.
Why it matters
It is the first link in the chain, and a value Google cannot attribute cannot influence bidding at all. A model can be perfect and still change nothing if the identifier never reached the CRM.
What goes wrong
It goes missing in six places, and none of them announce themselves: auto-tagging switched off during an analytics migration, a page that never reads the parameter, a visitor who moves to another page before submitting, a redirect that drops the query string, browser storage expiring before a long consideration cycle ends, and a CRM field that is never mapped or is overwritten by a later visit. The form still submits and the CRM still fills up throughout, which is why coverage falls quietly for months.
How to check it on your own account
Take leads from the last ninety days, keep the ones attributed to Google Ads, and count the share with an identifier. Break it down by landing page, form and browser; a single page or form is usually the culprit.
Next to this
- Auto-taggingGoogle AdsThe Google Ads account setting that appends the click identifier to your landing page URLs.
- gbraid and wbraidGoogle AdsClick identifiers for iOS journeys where a GCLID is not available.
- Match rateGoogle AdsThe share of your leads carrying something Google can join back to an ad click: a click identifier, or a usable email where enhanced conversions for leads is switched on.
- Enhanced conversions for leadsGoogle AdsMatching an offline conversion to an ad click using hashed first-party data, usually an email address, rather than a click identifier.
The rest of this step
Measure this on your own data
The diagnostic reads a CRM export in your browser and reports your volume, your match rate and the spread between your leads against the thresholds in this glossary. Nothing is uploaded and no account is needed.