Glossary/Measurement & Attribution/Click ID (GCLID / FBCLID)
Measurement & Attribution
Click ID (GCLID / FBCLID)
A unique parameter platforms append to ad click URLs, such as Google's gclid or Meta's fbclid, used to tie conversions back to specific clicks.
By Brandon Mina·CEO, BrandPilot AI·Updated November 2026
Short answer
A click ID is a unique parameter that an ad platform appends to the destination URL when someone clicks an ad, such as Google's gclid or Meta's fbclid. Websites store the ID and send it back with conversion data. This lets the platform tie each conversion to a specific click, campaign and keyword for attribution and bidding.