What is a Google tag manager - [Marketing Dictionary]

Google Tag Manager (GTM) is a powerful tool that allows marketers and webmasters to deploy and manage website tags (snippets of code) without modifying the website's core code directly. While GTM is often associated with analytics and marketing tags, it can also be leveraged to implement certain SEO improvements, particularly those involving the injection of scripts or structured data (schema markup) client-side.

What is Google Tag Manager and Why Use it for SEO?

GTM simplifies the process of adding, editing, and removing code snippets on your website through a user-friendly web interface. Instead of needing a developer to manually add code to page templates or individual pages, you install the GTM container snippet once, and then manage other tags (like analytics, remarketing pixels, or SEO-related scripts) within the GTM interface.

For SEO, GTM can be useful for:

  • Faster Deployment: Implementing certain SEO enhancements more quickly than waiting for standard development cycles.

  • Reduced Developer Dependency: Empowering SEOs to deploy and test certain code changes independently.

  • Centralized Management: Keeping various code snippets organized in one place.

It's crucial to understand, however, that GTM deploys code client-side using JavaScript. While Google is very capable of rendering and processing JavaScript, implementing critical SEO elements like canonical tags, meta robots tags, or essential site-wide schema markup directly in the server-side HTML is generally considered more reliable and is often processed faster by search engine bots. GTM is best used for enhancements or schema that are dependent on specific user interactions or dynamic page content that might be harder to implement statically.

Types of SEO Improvements Implementable via GTM (Scripts & Schema)

GTM can be used to deploy various code snippets beneficial for SEO:

  • Schema Markup (JSON-LD): This is one of the most common SEO uses for GTM. You can inject JSON-LD structured data for specific page types or content elements.

  • Tracking Scripts: Essential for measuring SEO performance (e.g., GA4 configuration and event tags to track organic traffic behavior).

  • Helper JavaScript Snippets: Small scripts that might dynamically add attributes, modify the DOM, or collect data useful for SEO analysis or other tags.

  • Event Tracking: Setting up tags to track user interactions (like clicks on specific links, form submissions, video views) that are important conversion or engagement signals influenced by organic traffic.

  • A/B Testing Scripts: Deploying scripts from testing platforms to run experiments on page variations, which can indirectly impact SEO by improving user engagement metrics.

Using GTM for Schema Markup (JSON-LD)

Implementing schema markup using JSON-LD via GTM is a popular approach, especially for schema types that might be challenging to hardcode directly into every template variation or are dependent on specific conditions.

Pros:

  • Allows for quick testing and iteration of schema implementation.

  • Centralizes schema management within GTM interface.

  • Can be ideal for schema types that apply only to specific pages or sections based on URL patterns or other GTM triggers.

Cons:

  • Code is injected client-side via JavaScript, meaning search engines need to render the page to access it (unlike server-side HTML). This could introduce a slight delay or dependency.

  • May not be suitable for schema that must be present and processed instantly on every page load for core functionality.

  • Requires careful setup of GTM variables to dynamically pull correct content for the schema (like product prices, article titles, etc.).

How to Implement Schema Markup (JSON-LD) via GTM (Step-by-Step)

The most common method is using a Custom HTML Tag in GTM:

  1. Identify the Schema Type and Pages: Determine which specific schema markup is appropriate (e.g., Article, FAQPage, HowTo, Product, LocalBusiness) and on which pages or templates it should appear.

Generate the JSON-LD Code: Write or generate the JSON-LD script for your chosen schema type. Use a schema validator tool (schema.org/docs/validator.html or Google's Rich Results Test) to check for syntax errors. For dynamic content (like the page URL, title, author, product price, rating), use placeholders for now – you'll replace these with GTM Variables.
JSON
<script type="application/ld+json">

{

  "@context": "https://schema.org",

  "@type": "Article",

  "headline": "PLACEHOLDER_HEADLINE",

  "image": [

    "PLACEHOLDER_IMAGE_URL_1"

   ],

  "datePublished": "PLACEHOLDER_PUBLISH_DATE",

  "dateModified": "PLACEHOLDER_MODIFY_DATE",

  "author": {

    "@type": "Person",

    "name": "PLACEHOLDER_AUTHOR_NAME"

  }

  // ... other properties

}

</script>


  2. Create a Custom HTML Tag in GTM:

    • Go to your GTM Workspace.

    • Click "Tags" > "New".

    • Name your tag clearly (e.g., "Schema - Article Pages").

    • Choose Tag Type: "Custom HTML".

    • Paste the entire <script type="application/ld+json"> block you generated in step 2 into the HTML text area.

  3. Configure GTM Variables: For the placeholders in your JSON-LD code, you'll need GTM Variables to pull the dynamic content from the page. This is often the most complex part. You might need:

    • Built-in Variables: { {Page URL} }, { {Page Path} }, { {Page Hostname} }.

    • Data Layer Variables: If your website's developers push data like articleTitle, authorName, productPrice to the Data Layer, you can easily access it using Data Layer Variables. (Requires developer involvement).

    • DOM Element Variables: You can configure variables to scrape text or attributes from specific HTML elements on the page (e.g., pull the H1 text as the article headline). (Can be less reliable if the site's HTML structure changes).

    • Once variables are set up, replace your placeholders in the Custom HTML tag with the correct GTM Variable names (e.g., replace "PLACEHOLDER_HEADLINE" with { {Article Title Data Layer} }).

  4. Configure Triggering: Define the trigger(s) that tell GTM when to fire this specific schema tag.

    • Click "Triggering" and add a new trigger.

    • Choose the trigger type that matches your target pages (e.g., "Page View" > "Some Page Views" where "Page Path" matches a specific pattern for all blog posts, or "Custom Event" if your developers fire a specific event on article pages).

  5. Test the Tag: Use GTM's "Preview" mode. Enter the URL of a page where the schema should fire. In the GTM debug console, check if your schema tag fired on the correct pages. Crucially, inspect the Data Layer and Variables tabs to ensure your GTM variables are correctly pulling the dynamic data needed for the schema.

  6. Submit Changes and Publish: If testing is successful, exit Preview mode, click "Submit" in GTM, and then "Publish" your container version.

  7. Validate Schema Implementation: Visit the live page and run its URL through Google's Rich Results Test and the Schema.org validator to confirm that the schema is detected and parsed correctly without errors. Monitor GSC's Rich Results Status reports.

How to Implement Other Scripts via GTM (General Steps)

For implementing other JavaScript snippets (like event tracking code or minor helper scripts):

  1. Identify the Script and Goal: What is the JavaScript code intended to do, and what action or condition should trigger it?

  2. Create a Tag:

    • Click "Tags" > "New".

    • Name your tag (e.g., "GA4 - Track Button Click").

    • Choose Tag Type: Use "Custom HTML" for full <script> blocks or "Custom JavaScript" if you are just adding JavaScript code. For specific tracking like GA4 events, use the dedicated "Google Analytics: GA4 Event" tag type.

  3. Add the Script/Configuration: Paste or write your JavaScript code. Configure the tag settings (e.g., select your GA4 Configuration Tag for event tags). Use GTM Variables as needed to capture dynamic values related to the event (e.g., button text, form ID).

  4. Configure Triggering: Define the trigger(s) that determine when this script fires. This might involve setting up:

    • "Page View" triggers (for scripts that load on specific pages).

    • "Click" triggers (for tracking button or link clicks).

    • "Form Submission" triggers.

    • "Element Visibility" triggers.

    • "Custom Event" triggers (often set up by developers to signal specific actions in the Data Layer).

  5. Test and Publish: Use GTM's Preview mode to ensure the script fires correctly when the defined trigger conditions are met. Publish the container when confident.

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