Setting Up Google Tag Manager and Your First Tag

01What Is GTM and What Is It For?

Google Tag Manager (GTM) is a free tag management system that lets you manage the analytics, advertising and measurement codes on your site from a single panel. The container code is added to the site just once; other codes such as GA4, Google Ads and the Meta Pixel run from inside that container.

Its biggest benefit is not depending on a developer and a code release for every new measurement need. The marketing team prepares a new conversion tag in the panel, tests it in preview and publishes it. Because every publish is stored as a version, a faulty change can be rolled back with one click.

GTM also comes with a responsibility: anyone with access to the container can add code to the site. That is why you need to hand out permissions carefully and clean up unnecessary tags regularly.

02Tags, Triggers and Variables

Three core concepts are the key to understanding GTM. Every setup is made of these three pieces linked together.

What is the data layer?

The data layer is a shared JavaScript array through which your site passes information to GTM. You write data that is not visible on the page, such as an order number, product information or form name, into it; GTM reads this data as variables and passes it to tags. That way, measurement rests on a solid base that does not break when the page design changes.

03Creating an Account and Container

Go to tagmanager.google.com with the business's Google account. The account and container should be created in the business's name, with an agency given user access only; when the collaboration ends, your measurement infrastructure stays with you.

1. Press the Create account button, enter your business name as the account name and choose your country.
2. Enter your site's address as the container name and choose Web as the target platform.
3. Accept the terms of service; the installation codes appear on the screen.
4. Note the container ID that starts with GTM-.

04Adding the Container Code to Your Site

GTM gives you two code snippets. The first must sit in the head section of every page, as high as possible. The second is a fallback for browsers with JavaScript turned off and is added immediately after the opening body tag. If you use a shared template or header file, adding the code in just one place covers all pages.

<!-- Google Tag Manager -->
<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
})(window,document,'script','dataLayer','GTM-XXXXXXX');</script>
<!-- End Google Tag Manager -->

<!-- Google Tag Manager (noscript) -->
<noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-XXXXXXX"
height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
<!-- End Google Tag Manager (noscript) -->

Adding it from the platform admin panel

Many ready-made systems offer a separate field for the container ID and place the code in the right spots themselves. In Aurora's e-commerce infrastructure, the Google Tag Manager code is added from the panel, and a live check screen shows whether the code is actually running.

05Your First Tag: The GA4 Google Tag

Once the container is loaded, the first job is usually to start GA4 measurement through GTM. If you do not have a GA4 property yet, first get the measurement ID by following the Google Analytics 4 setup steps.

The Google tag collects page views and enhanced measurement events. For additional events, you create separate GA4 Event tags, enter the measurement ID and the event name, and attach them to the right trigger. The same logic applies to Google Ads conversions: you simply create a Google Ads Conversion Tracking tag with the conversion ID and label from the Google Ads panel and attach it to the thank-you page or the purchase event. Keeping a consistent order of tool, type and purpose in tag names makes it easy to find what you need as the container grows.

1. From the Tags menu, press the New button and give the tag a clear name (for example GA4 - Google Tag).
2. In the tag configuration, choose the Google Tag type and enter your measurement ID that starts with G-.
3. In the Triggering section, choose the Initialization - All Pages trigger so the tag loads before other tags.
4. Save. The tag is not live yet; preview and publishing come next.

06Sending Events with the Data Layer

Having the site write an event to the data layer at key moments, such as a form submission or a purchase, is the most reliable measurement method. Triggers based on visible elements such as clicks or page URLs can break silently when the design changes.

In the example below, when the form is submitted successfully, an event named form_gonderildi is written. In GTM, you create a trigger of the Custom Event type with the event name form_gonderildi and attach the GA4 Event tag to it. To read the form name, you define a variable named form_adi of the Data Layer Variable type.

window.dataLayer = window.dataLayer || [];
window.dataLayer.push({
  event: 'form_gonderildi',
  form_adi: 'teklif_formu'
});

In single-page applications (SPA)

In single-page applications written with React or Vue, page transitions do not reload the browser. In this case you can use the History Change trigger, or have the router write an event to the data layer every time the page changes. We cover project setup in our React setup with Vite guide.

07Preview, Testing and Publishing

Never publish a change without testing it. The Preview button at the top right opens Tag Assistant; when you enter your site's address, the site opens in debug mode and you can see, page by page or event by event, which tags fire and which do not.

If you are happy with the test, press the Submit button and give the version a descriptive name and a short note. Writing what changed in the version name makes it easier, months later, to find which change caused a measurement problem.

• Also verify on the GA4 side that events arrive, using the DebugView screen.
• If something goes wrong, you can republish the previous version from the Versions menu.
• In larger teams, open separate workspaces to keep changes from getting mixed up.

08Common Mistakes and Best Practices

Over time, unused tags pile up in the container, and each one adds to page load. Reviewing the container every three months and pausing unused tags reduces both measurement clutter and the load on page speed; this is also a regular part of our speed and performance management work.

Advertising and measurement tags should not run without visitor consent. GTM's consent settings and the Consent Mode configuration manage this flow. This post gives general information; for your cookie consent setup, check current legislation and consult your legal advisor.