GCLID PII Information

The GCLID is a unique code generated to label a click on a particular ad property on a url and does not contain any PII.

The GCLID’s can only be used for bidding on clicks on Google Ads properties.

As GCLID does not contain any user PII, therefore the GCLID cannot be used for retargeting users. No user consent is required.

The following examples from google show that no user PII is included in the GCLID:

Scenario 1

User A clicks an ad and lands on your website. Provided auto-tagging is on, the destination URL might look something like this:

http://www.example.com/?gclid=TeSt123Abc

where the gclid parameter is the auto-tagging parameter.

User A then copies this URL (containing the auto-tagging parameter) and posts it in another location such as a public discussion board (forum) or a social network, or sends it in an email or chat window to other recipients.

Next, User B clicks this link (containing the gclid value) and arrives at your website. Even though User B has never been to the website before, this user will have the first session attributed to the same click id (gclid) value that was assigned to the original User A. In this case, you see new sessions (caused by User B) from an old campaign. Summary Even though user A & B will have different PII the GCLID will be seen as the same. Thus no PII included in GCLI

Summary

Even though user A & B will have different PII the GCLID will be seen as the same. Thus no PII included in GCLID.

Scenario 2

This second scenario is similar to the first. Imagine a user clicks on your ad and lands on a page containing the gclid parameter, e.g.

http://www.example.com/?gclid=TeSt123Abc

The user bookmarks the page immediately. The bookmarked URL contains the auto-tagging parameter gclid (click id). However, this user regularly clears cache and cookies on their device.

When these cookies are removed and the user returns to your website via the bookmark URL, the user appears as a new user (first time user) to Analytics, and the gclid value will cause Analytics to treat the session as a new session attributed to the original Google Ads campaign

Summary

Even though the one user has the same PII for both clicks: a new unique GCLID will be applied to the second click. Thus no PII included in GCLID.