Google Tag Manager is also known as GTM, is a free container tag system from Google. A container tag helps you manage different kinds of tags that you may have on your site. This include web analytics tags, advertising conversion tags, general JavaScript, etc.
Users can add and update their own tags anytime. It’s not limited to Google-specific tags. It includes asynchronous tag loading, so “tags can fire faster without getting in each other’s way,” as Google puts it. It comes with tag templates for marketers to quickly add tags with Google’s interface, and supports custom tags. It also has error prevention tools like Preview Mode, a Debug Console, and Version History “to ensure new tags won’t break your site.”
