Google Tag Manager Review — Prt 1

A learning journey with CXL Institute, in Digital Analytics

In previous posts, we talked about Google Analytics and how to present data with different tools. But, in order for all of these to happen, you first need to collect your data. From today and a few weeks onwards, we are going to discover the tool that makes all of these possible: Google Tag Manager. Welcome to my 6th week, reviewing the CXL Institute Minidegree for Digital Analytics.


In this week’s post, we will define the basic terminology of Google Tag Manager — also goes by the name GTM — and we will describe the basic functionalities.

So, let’s get started…

Why Google Tag Manager

Before start talking about variables and triggers and tags and dig into details about all the features, we first need to answer this:

Why Google Tag Manager?

Well, GTM is free and allows you to manage and deploy marketing snippets of code or tracking pixels on your website (or mobile app) without the requirement of programming knowledge. It is very easy to learn and very handy when you have lots of tags to manage because all of the code is stored in one place.

Now that you know how to answer the question, let’s start with the basic components of GTM and how they can be used.

Getting to Know GTM: Container

The Google Tag Manager container snippet is a small piece of JavaScript and non-JavaScript code that you paste into your pages.

As your Google Tag Manager implementations grow over time, it is a good idea to organize your containers. You can have multiple containers under one account. Think of a Google Tag Manager container, as the Google Analytics property. You organize your properties based on a domain, or an app. That is exactly the strategy you need to follow for your Google Tag Manager containers, as well.

Getting to Know GTM: Tags

A “tag” is basically the script. It’s the code that instead of copying and pasting — for example, Google Analytics code snippet — you would let tag manager do that for you. And in general that is the main scope of a tag: instead of copying and pasting every script (e.g. Hotjar, Facebook Pixel, Google Ads, etc.) to individual pages, you would let tag manager to put the scripts on the pages at the appropriate times, so the platforms know what’s going on.

Getting to Know GTM: Triggers

The most descriptive way to think about “triggers” is when do you want Google Tag Manager to take an action.

So, let’s combine the knowledge of the two components (tags & triggers) into our heads:

We said that tags are the scripts we want tag manager to put at the appropriate times, on specific pages. But when the time is appropriate? and who is deciding the specific pages? That’s where triggers are getting into the process. Triggers tell to tag manager when and where to fire a tag.

Getting to Know GTM: Variables

A variable is the information that Google Tag Manager needs, in order to do its job.

So let’s connect the dots again:

  • the tag tells Google Tag Manager what it needs to do,
  • the trigger tells Google Tag Manager when it should do it,
  • the variable tells Google Tag Manager, here’s the information you’re going to need, in order to do the thing that you need to do when you need to do it.

Are you still with me?

Getting to Know GTM: Data Layer

A data layer is a JavaScript object that is used to pass information from your website to your Tag Manager container. Sometimes as different behaviors are happening, you need to be able to temporarily store those details somewhere, so you can reference them at a later time.

Let’s take as an example an e-commerce transaction. When an ecommerce transaction is happening you want to be able to store different details long enough so that you can send them to all the different platforms (product, price, size, etc.). The way to think about the data layer is a little virtual filing cabinet.

A data layer can be used as a variable within the Google Tag Manager structure.

Getting to Know GTM: Preview Mode

So, let’s imagine you defined your tags, your triggers and variables in order to collect a specific information. What’s next? Does it work? Do you proceed and publish those changes?

That’s where Preview Mode comes into the play…

Google Tag Manager’s Preview Mode allows you to browse a site on which your container code is implemented, so that you can test a container configuration before it is published.

Getting to Know GTM: Workspaces

A Google Tag Manager workspace allows you to create multiple sets of changes for your container. It is very handy when you have multiple team members working on changes at the same time. With this feature they can work in separate workspaces to independently develop their own tag configurations, without compromising the work of each other.

This feature helps with version control by giving you the ability to revert changes to a previous workspace configuration, and helps prevent teammates from inadvertently publishing someone else’s unfinished changes.

A workspace is the place you make changes every time you work on a container. Every container creates a default workspace. You can add up to two additional workspaces for regular accounts, and can create an unlimited number of workspaces for Tag Manager 360 accounts.

Final Thoughts

We started slow but steady in this course of CXL institute. There are a lot of different things we need to cover for this — amazing — tool called Google Tag Manager, and we need time to consume them all. So, for the next weeks my posts will be dedicated to Google Tag Manager course series and we will cover every little detail we need to know, in order to properly collect our data.

My name is Alexandra Poulopoulou and I work as a Data & Analytics Lead at Reprise Digital. During my professional years, I have been involved in several analytics projects in order to drive successful business decisions.

If you liked what you’ve just read, follow me on Medium, LinkedIn or Twitter, because there are many of these to come. See you next time…

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