What is Tag Manager?
Tag Manager is a tool created by Google that helps marketers improve their website for themselves as well as their consumers. It can make the website easier to navigate, along with having reactions and links work faster. As for the marketer/ company, you can gain more data on what happens while people are on your site. Tag manager focuses on improving 3 main categories to improve, speed, consolidation, and workflow.
When will Tag Manager be used?
After you have installed google tag manager your next step is to set up the tags, for different events. When one of the events occurs the tag will be triggered. For instance, a consumer has reached the bottom of your page and you set off that as a trigger to ask for their email address. Now they can keep learning about your new products, information, and deals. This data is also more specific than other analytics you might see, you can now see who views a video, how much of it they watched it, and even if they played it twice. Tag managers will add so much value and information to your business and help you understand what customers are doing on your site, and also be able to help you redirect them to what you want them to do next.
Below is a video by Elevar, explaining more benefits of Google tag manager.
https://support.google.com/tagmanager/answer/6102821?hl=en&ref_topic=3441530