Google Tag Manager
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.
To set up Google Tag Manager on either your Drupal or WordPress site…
Create a GTM Account
Install the extension into your Content Management System
Drupal: google_tag module
WordPress: Site Kit Plugin
Visit the configuration screen of the extension, and paste the supplied Code or ID into your application
Review some of the advanced settings are set up properly…
Drupal: Ensure the "include the snippet as a file" setting is DISABLED
Configure Tags & Triggers for Google Analytics or other properties
That’s it.
GTM Configuration
The rest of GTM is tags & triggers that register events with given services.
When you log in to Google Tag Manager, you are presented with two tabs, Workspaces and Google Tags. Google Tags are groups or individual tags related to services. If you’ve generated a connection through a plugin, it should show up in Google Tags. Otherwise, if you want to create a tag setup from the ground up, create an account.
Account
Once created, a new account will allow the creation of subtags and their triggers, which in turn capture events for their relevant services.
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.
Useful Links
Set up and install Tag Manager