Google Tag Manager is a tool which enables the top-down configuration of Google tags on each of your sites. Within sites and apps, you can add snippets of code that allow the manager to add further Google related configuration to your site, like Ads and Analytics. This means most people can manage the integration without developer changes to site code.
Setting Up GTM on a Site
Most CMS platforms have plugins or modules which assist with the placing of a GTM tag on your site! It is worth checking for a canonical method for adding head script tags to your stack before development.
For example for Drupal there is the Google Tag plugin, and in WordPress’s case, you can simply add the code to the global header.
Otherwise, the steps are as simple as:
Create a GTM Account
Paste the supplied Code or ID into your application
Configure Tags & Triggers for Google Analytics or other properties
That’s it! The rest of mastering GTM is understanding what Tags and Triggers can do.
Tag
Tags are simply event identifiers. When a tag is triggered (by a trigger), the resultant data is sent to the relevant service.
Trigger
Triggers are what cause a tag’s recording, whether that be a page load or some user interaction.