Last Updated on October 12, 2026

Tag Manager Overview

(Based on Google’s Documentation)

Google Tag Manager is a tag management system (TMS) that lets you set up and manage measurement code, collectively known as tags, without editing your website’s code. To use it, you add two small snippets of Tag Manager code to every page of the site once. After that, tags are added and managed through the Tag Manager web interface instead of the site’s code.

When Tag Manager is installed, your website or app communicates with the Tag Manager servers. From the Tag Manager interface you can set up tags, create triggers that tell a tag when to fire, and create variables that simplify and automate your tag configurations.

The collection of tags, triggers, variables, and related settings installed on a website or app is called a container. A container can replace the manually coded tags on a site, including tags for Google Ads, Google Analytics, Floodlight, and 3rd party platforms like Meta.

Using Google Tag Manager to Simplify Tag Implementation

(In Sebo’s Words)

Google Tag Manager was created to make implementing tracking across different platforms simpler. Before Tag Manager, a webmaster or agency needed access to the backend of the website to go into the header or footer code and add each tag separately. That meant multiple people signing into the backend of the website constantly, which is a security issue, and it left the site with messy backend code. Tag Manager solves both problems.

Once Tag Manager is installed, we can add any other tracking code through Tag Manager without signing into the backend of the website. With GTM (Google Tag Manager) in place, the GTM container code should be the only tracking code that needs to live in the site’s code.

If a website links to another website, we can’t track what happens on that other site because our tracking code isn’t there. The same goes for 3rd party elements embedded on the site, like YouTube videos. GA4 now tracks outbound link clicks and YouTube video engagement automatically through enhanced measurement, so GTM isn’t required for the basics. Where GTM comes in is anything more specific: tracking clicks to one particular partner site, a phone number click, a button that isn’t a link, or sending those same actions to Google Ads or Meta as conversions.

GTM User Interface

Google keeps an up-to-date walkthrough of the Tag Manager interface, including workspaces, the Tags, Triggers, and Variables menus, and where to find the Preview and Submit buttons. Review Find your way around Tag Manager before making changes in a client’s container.

Tags, Triggers, & Variables

Tags, triggers, and variables are how we use GTM. With these we can install GA4, track phone call clicks, track form submissions, and send conversions to Google Ads and other ad platforms.

Tags and Triggers

A tag is a snippet of code that runs on a page. Most tags in Google Tag Manager send information from the site to another platform. Examples include the Google Tag, GA4 Event tags, and the Google Ads Conversion Tracking tag, which send information about activity on the site to Google.

Note: The Google Tag is not the same thing as Google Tag Manager. The Google Tag is the base code for GA4 and Google Ads. Google Tag Manager is the system we use to install and manage the Google Tag along with every other tag on the site.

Without a tag management system like Google Tag Manager, the code for each tag has to be added directly to the site’s source code. With Google Tag Manager, all of those tags are controlled from one web interface.

Tags typically fire when the page loads or in response to an interaction on the page. In Google Tag Manager, you attach triggers to tags to specify when they should fire. An example is the built-in “All Pages” trigger, which fires a tag on every page of the site as it loads.

Triggers and Variables

A trigger is a condition that evaluates to either true or false when the page runs. It does this by comparing the value in a variable to the value you set when you created the trigger.

A Tag Manager variable is a named placeholder whose value is filled in when the page runs. Tag Manager has many built-in variables, and you can create custom variables as well.

For example, the built-in variable Page URL always contains the URL of the page that’s currently loaded. If you want a tag to fire only on the page example.com/purchase/receipt.html, you would create a trigger that looks like this:

  • Trigger Type: Page View
  • This trigger fires on: Some Page Views
  • Fire this trigger when an Event occurs and all of these conditions are true:
    Page URL contains example.com/purchase/receipt.html

You can create variables to hold any piece of information you need when the page runs, then use them in trigger conditions or pass them to tags. For example, you might create a variable that holds the price of the item a user is viewing, or a constant variable that holds a client’s GA4 Measurement ID.

Event and Key Event Tracking

One of the main things we use GTM for is tracking events. In GA4, every action is an event, including page views. Some events are collected automatically, and others we create in GTM for actions that matter to a specific client, like watching a video, clicking a social media link, or clicking through to the contact page. These are the actions that make a visitor more likely to become a lead or customer.

The most important events are marked as key events in GA4. Key events are what we used to call goals or conversions in Analytics: form submissions, phone call clicks, purchases, and other actions that directly bring value to the client. Any event can be marked as a key event in GA4 under Admin > Data display > Events. Events aren’t limited to Analytics either. The same GTM trigger can fire a GA4 Event tag, a Google Ads Conversion Tracking tag, and a Meta tag at the same time.

For example, a “thank you” page that loads after a form submission can be tracked with a Page View trigger on that page’s URL. But if a form shows a confirmation message without loading a new page, there’s no page to track. In that case, we create an event in GTM that fires when the form is submitted, send it to GA4, and mark it as a key event.

Always test before publishing. Click Preview in GTM to open Tag Assistant and confirm your tags fire on the right actions before you click Submit. Changes in GTM go live on the client’s site as soon as they’re published. Learn more about Preview mode.