What is a click ID?
A click ID is a unique code attached to a single ad click. The traffic source adds one to the link, such as Meta's fbclid or Google's gclid, and the tracker creates its own. The code travels with the visit so that later events, including feed revenue, can be matched back to the exact advert that produced them.
A Click ID is the thread that holds the data together. It is passed to the feed as a Sub ID or similar field, returned in the postback and sent on to the traffic source. Break the thread at any point and revenue becomes unattributable.
It differs from UTM parameters, which describe a group of clicks (source, campaign, creative) and are the same for everyone who clicked the same ad. Click IDs are individual. Because they identify a visit, they fall under privacy rules in some regions, and browsers increasingly strip known ID parameters from links. Server-side handling and proper consent management keep attribution working within those limits.