The Google Tag and Tag Manager

This page provides an overview of the Google tag, Google Tag Manager, and gtag.js, and explains how to use them to set up tagging on your website. If you're setting up Google Analytics on an app, see Set up app measurement.

The Google tag

The Google tag is a single tag you can add to your website to measure website and ads performance. You must use the Google tag to send data to Google Ads and Google Analytics 4 (GA4). The accounts you send Google tag data to are also called destinations.

The Google tag is the basis for all measurement use cases. If you use Google Ads or GA4, the product auto-generates a Google tag for you.

Here are some benefits of using the Google tag:

This tagging option is great for marketers who don't have a web development team readily available or use a content management system (CMS). If you only need the default metrics, such as page views, clicks and scrolls, you can set up the Google tag once and you're all set.

Here's how to get started with the Google tag:

If you need more tagging options, add Google Tag Manager or gtag.js to your implementation.

Google Tag Manager

Google Tag Manager is a tag management system that lets you update tags on your website or mobile app from a web interface. You can use Google Tag Manager to load a Google tag on your website instead of manually adding the Google tag code snippet to your site.

Google Tag Manager supports Google-specific tags, a wide array of third-party tags, and even custom tags. For details on the supported tag options, see all supported tags.

Google Tag Manager might be helpful for marketers who are in charge of tagging and need to manage Google and tags from other parties. It's also a good option for tag administrators and agencies, and can be used alongside site code changes.

Set up and install Tag Manager →

If you were using GA4 configuration tags, they have been automatically upgraded to the Google tag. Your measurement and capabilities haven't changed, and you don't need to take any action. Your GA4 event tags stay the same.


If you already use Google Tag Manager, you don't need to use gtag.js. Google Tag Manager fully supports Google Ads and Google Marketing Platform tags, and you don't need to deploy additional code using gtag.js on your site.

The Google tag uses the gtag.js JavaScript framework to add Google tags directly to web pages. To use gtag.js effectively, you need to be proficient in HTML, CSS, and JavaScript.

gtag.js is best for web developers who are in charge of tagging and only need to manage Google tags. gtag.js lets you install tags directly on your web page, without the ramp-up time of setting up a tag management system.

If your tagging needs evolve, you can migrate your tags to Google Tag Manager at a later date.

For the latest information on cookie usage in Google Analytics 4, see Cookie usage on websites.

The gtag.js JavaScript library uses first-party cookies to do the following:

  • Distinguish unique users.
  • Distinguish sessions for a user.

When using the recommended JavaScript snippet, cookies are set at the highest possible domain level. For example, if your website address is, gtag.js sets the cookie domain to Setting cookies on the highest level domain possible lets measurement occur across subdomains without extra configuration.

gtag.js sets the following cookies:

Cookie name Default expiration time Description
_ga 2 years Used to distinguish users.
_ga_<container-id> 2 years Used to persist session state.


To learn how you can customize the default cookie settings using gtag.js, see Cookies and user identification guide.

Google Tag Manager versus gtag.js

The following table highlights the differences between Tag Manager and gtag.js.

gtag.js (code deployment)

Google Tag Manager (Tag Management System)

You need to write code to deploy tags and customize your web collection

Deploy and modify both tags from Google and third-parties on the fly without editing code.
See all supported tags

Can only send data for Google products.

Can send data for Google tags, third party tags, and custom tags.

You need to manage your tags from within your code, and may need to duplicate code for different outlets, for example, web and app.

Manage tags for your website and apps all from

Version control depends on how you manage your code.

Collaborate with others using workspaces, and version control tags.

Server-side tagging is possible. You still need to use Google Tag Manager to deploy and interact with your server container.

Tag Manager helps you deploy tags on a server. If you are exploring this option, read Client-side and server-side tagging.

Compatible with static-site generators, CMSs, website builders or manually authored HTML pages that support JavaScript.

Compatible with many CMSs and website builders. If your system doesn't support Tag Manager, use the Google tag (gtag.js) instead.

Cost: Free

Cost: Free

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