What Does Tag Manager Do?
Google Tag Manager allows you to easily update measurement codes called tags on your website. With these tags, you can set up triggers which fire off when certain events occur. One example of a tag is the measurement of button clicks on your site. As a website owner, it is really useful to be able to see where people click on your site, and how many times.
Further Explanation
Once you have linked your website to Google Tag Manager, you are free to set whatever tags you want. For example, you can set a tag on your add to cart button which shows you how many people have at least thought about buying something. Within that, you could also set a tag on the check out button to see how many of those people actually bought the product. Depending on the results that you get, you can either try and change things up, or continue with what’s working.