Google Click Identifier, or GCLID, is a globally unique tracking parameter used by Google to pass information back and forth between Google Google Ads and Google Analytics.
It is enabled by turning on auto-tagging in your Google Ads account or by using the GCLID parameter on the final URL suffix.
It is an extremely important parameter that allows our system to differentiate organic traffic - which doesn't have the GCLID value in the URL - from paid traffic - which does include the GCLID value in the URL.
If you have any questions about this process, feel free to reach out to our 24/7 chat support.