Components of Google Tag Manager
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Components of Google Tag Manager
Understand how tags, triggers, variables, and the data layer work together.
Google Tag Manager uses these concepts to handle how tags are configured and fired:
Tag: A tag is code that send data to a system such as Google Analytics.
Trigger: A trigger listens for certain events, such as clicks, form submissions, or page loads. When an event is detected that matches the trigger definition, any tags that reference that trigger will fire.
Variable: A variable is a named placeholder for a value that will change, such as a product name, a price value, or a date.
Data layer: Tag manager implements a data layer to temporarily hold values in the client so that they can be used by tags, triggers, and variables.
In this article we will explore how these concepts work together.
If you don't use a tag management solution, the code for each tag is added directly to the source code. With Tag Manager, you instead control all of your tags from a web user interface.
Triggers and variables
Event: Page View
Trigger Type: Page View
Fire On: Some Page Views
Fire the tag when these conditions are true: URL contains example.com/purchase/receipt.html
Configure built-in variables or custom variables to make information available to your application when you need it. Use these variables in trigger conditions or to pass information to tags.
Variables and the data layer
You don't necessarily need to set up a data layer in order for variables to retrieve information. Tag Manager Variables can also be configured to retrieve values directly from JavaScript variables, first-party cookies, from the DOM. However, the best practice is to have your variables retrieve information directly from a well-organized data layer object. A data layer implementation can minimize the likelihood of data loss from inadvertent code changes, encourage a well organized and accessible data model, and simplify troubleshooting.
Note: For web applications, every page must have code that adds the needed information onto the data layer. The data layer does not automatically persist across pages.
Data layer implementation scenarios
Consider these points help you decide if a data layer implementation is right for your needs:
If your tags only need to fire when pages load (i.e. they don't need to fire in response to user interactions on the page) and the tags don't need any information beyond URL and referrer, you only need to add the container snippet to each page of your site. A data layer implementation is probably not necessary.
If your tags only need to fire when pages load, but need information beyond URL and referrer (such as the page type or user ID), you may need to add code that creates a data layer and pushes information to it.
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