GCLID stands for Google Click Identifier, a unique tracking parameter Google adds to every ad click when auto-tagging is on. Google uses it to pass click information between Google Ads and Google Analytics. ClickGuard uses it too, to identify each individual ad click, so it can monitor and analyze every visit from your ads.
GCLID stands for Google Click Identifier, a unique tracking parameter that Google uses to transfer information between your Google Ads and Google Analytics accounts.
This parameter allows Google Analytics to track and provide detailed information about a specific user's session. It is also utilized by ClickGuard to identify individual ad clicks for monitoring and
analysis.
The GCLID is automatically appended to the final URL of your ads when the "auto-tagging" feature is enabled in your Google Ads account.
See also: What is Google Ads' final URL suffix.