What Is Google Click Identifier (Gclid)?

Gclid is a globally unique tracking parameter (Google Click Identifier) used by Google to pass information back and forth between Google AdWords and Google Analytics. If you enable URL auto tagging in Google AdWords, Google will append a unique ?gclid parameter on your destination URLs at run-time.

How is it useful?

The gclid parameter is used to help identify and tell apart CPC (Cost-per-click/Adwords data) from Organic traffic enquiries of a website.

How is it done?

In order for the gclid parameter appear in your AdWords traffic enquiries, you must do one of the following:

Enable auto-tagging. Sign in to your AdWords account. Click the gear icon, and select Account settings. Make sure you’re on the Preferences tab, and click Edit in the Tracking section. Select (enable) or clear (disable) the Auto-tagging checkbox. Click Save changes.

This is the recommended approach and ensures that you get the most detailed AdWords data. Manually tag all your keyword final URLs with tracking variables. You should only do this in the special cases outlined below.

How auto-tagging works: Auto-tagging automatically imports AdWords data into Analytics. Combining AdWords data with the rich post-click information provided by Analytics allows you to see what happened on your site after people clicked on your ads.

When you enable auto-tagging, a parameter called gclid is added to your landing page URL when a user clicks over to your site from an ad. For example, if your site is www.mysite.com, when a user clicks on your ad it appears in the address bar as:

www.mysite.com/?gclid=123xyz

How to identify if the individual traffic was CPC or organic?

Choose the IP address of the visitor on that day. Get the visitor traffic data from your website hosting provider’s server logs. Extract log date and open with Notepad++ software. Use Ctrl + F function to look for the IP address. If the IP address has a “gclid” attached in the string then it is CPC.