Google Tag Manager is a tag management system that allows you to quickly and easily update and manage tags on your website or mobile app. Tags are measurement codes and related code fragments that are added to your project, which can then be easily deployed from the web-based user interface. In addition, there exist Triggers, which tells Google Tag Manager when and how to fire these tags; and Variables, which store any other additional information Google Tag Manager may need in order for the tags and triggers to work. For more information, click the following links:
Google Tag Manager is solely responsible for storing and managing third-party codes, therefore it is unable to provide any reports or analysis on the tags that were assigned. However, you are able to connect your Google Tag Manager with Google Analytics in your flow, which is used for the actual reporting and analysis.
Niro recommends using Google Tag Manager if your tag firing scenarios are more complex i.e., you are implementing more customized containers in addition to the basic container configuration. Naturally, you can also use Google Tag Manager for the basic configuration because all third-party code is all located in one place, which results in easier management. Additionally, it is important to think about who will manage the Google Tag Manager account, by defining account ownership roles for the members of your organization. Google Tag Manager allows you to add users and set permissions to each member.