Comment by sandspar

Google Tag Manager lets you add tracking stuff on your website without needing to touch the code every time. So if you want to track things like link clicks, PDF downloads, or people adding stuff to their cart.

It doesn't track things by itself. It just links your data to other tools like Google Analytics or Facebook Pixel to do the tracking.

This kind of data lets businesses do stuff like send coupon emails to people who left something in their cart.

There are lots of other uses. Basically, any time you want to add code or track behavior without dealing with a developer.