With server side tagging, such as via Google Tag Manager, this process is changed by adding an extra layer. We call this the server side container in Google Tag Manager. Instead of direct communication from the browser to remote servers, the data is first sent to a subdomain that you control. This subdomain acts as a kind of “way station” where the data is collected, filtered, and then forwarded to the external parties. Apart from being more measured, you also have much more control over data quality and your website becomes a lot faster.