Google Tag Manager overview
Google Tag Manager is a tag management system that allows you to quickly and easily update tags and code snippets on your website or mobile app. Once the Tag Manager snippet has been added to your website or mobile app, you can configure tags via a web-based user interface without having to alter and deploy additional code. This reduces errors and frees you from having to involve a developer whenever you need to make changes.
Tag Manager for web works via its own code snippet that you add to your website or mobile app. This code connects your website or app to the Tag Manager servers. You then use the web based user interface to set up tracking tags, establish triggers that cause your tag to fire when certain events occur, and create variables that can be used to simplify and automate your tag configurations.
A collection of tags, triggers, variables, and related configurations installed on a given website or mobile app is called a container. A container replaces all other manually-coded tags on a site or app, including tags from AdWords, Google Analytics, Floodlight, and 3rd party tags.
When you upgrade your site or app to Tag Manager, the best practice is to migrate all your tags at once. However, this is not a mandatory requirement. Tag Manager can fire your migrated tags alongside any tags that are not administered through Tag Manager.
Your Tag Manager account allows you to administer the tags for one or more websites or mobile apps. Although you can set up multiple Tag Manager accounts from a single Google account, you’ll typically only need one Tag Manager account per company or organization. Learn more.