To gain the most value from Google Tag Manager, you should migrate all (or as
many as possible) of your existing tags into Tag Manager. The recommended steps
are as follows:

1. **Map your site (optional)**

   Think about which tags you might currently have deployed on your site. Think
   about what actions (events) you want to track and what data (variables)
   you'll want to collect. Create a map of tags, the data to be collected, and
   which events or pages you want to associate with those tags.
2. **Install the Tag Manager code on your site**

   Once you've mapped your site, install the Tag Manager container tag on your
   site and deploy it. Read the [installation guidance](https://support.google.com/tagmanager/answer/14842164) for more information.
3. **Add Events and Variables**

   Customize your Google Tag Manager installation using the methods outlined in
   the [events guidance](https://developers.google.com/tag-platform/gtagjs/reference/events).
4. **Configure tags and their associated triggers in Tag Manager**

   Once Tag Manager is installed on your site, you should add your site tags to
   the user interface. DO *NOT* publish at this time. Simply add and configure
   the tags from your site in Tag Manager with appropriate tag templates and
   triggers. [Learn more about triggers](https://support.google.com/tagmanager/topic/7679384).
5. **Final migration swap**

   The last step is where you simultaneously swap out your old tags and publish
   your tags in Google Tag Manager. Within a few minutes of each other, you'll
   want to:
   - Remove your site tags in a single code push
   - Once you know this push is successful, press the "Publish" button for your container version.

   This method might cause a small gap in data, but once the initial swap is
   complete, no more gaps will appear. Alternatively, you could swap the order
   here and publish shortly before your site changes go live. This might cause
   minor, one-time data duplication instead of a small data gap.

After you've completed the initial migration to Tag Manager, any subsequent tag
configuration needs can be handled without code changes via the Tag Manager
interface.