Before we can answer why you need google tag manager, it would be helpful to first explain what it actually is.
Google Tag Manager, also referred to as GTM, is a free tool to accompany google analytics. It allows us to track our sales funnel in more detail and create custom 'Tags' to measure when specific buttons are clicked, certain pages are visited or a whole host of other actions visitors take on our website.
Why is that useful?
Well, it comes in really handy if you're trying to streamline your sales process and figure out where your leads are dropping out. By tagging certain actions along the sales funnel on our website, we can see what percentage of visitors make it to each stage.
This means that, if, for example, 100 people make it to the lead capture page, but only 5 people sign-up, then we know that we can make some improvements to the page or the offer.
It's essentially just another tool to have in your arsenal ready to use!
Here's a great post to explain a bit more about Google Tag Manager & why you need it.