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.