How AdWords tracks website conversions
This article provides more information about how we measure the interactions that people had with your ads before a conversion, including some recent changes we’ve made.
How website conversion tracking works
When people click on your ads, AdWords stores a cookie that contains information about the click on a Google domain. When someone converts on your website, the conversion tracking tag you installed reads this cookie and sends it back to AdWords with the conversion information. In some cases, the cookies we use to store information about your ad clicks may not be available due to factors including browser settings. To help ensure that we continue to report conversions accurately in your AdWords account, we're making several changes.
What’s changing
First, if you have auto-tagging enabled for your account and a Google Analytics tag on your website, we’ll begin to store the GCLID, or “Google click identifier” for an ad click in a new Google Analytics cookie on that site’s domain. If you’ve linked your AdWords and Google Analytics accounts, the AdWords conversion tracking tag will be able to use the GCLID from the Google Analytics cookie.KeepReadinghttps://goo.gl/ub8MSV