If you use Facebook Pixel, Google Analytics, conversion tracking, and other marketing tools, each one requires code on your website. Managing all that code is messy and slow. Google Tag Manager (GTM) solves this — install it once, then add, edit, or remove any tracking tag from a single dashboard.
For example, if you run an e-commerce site and want to track purchases, page views, and cart abandons, GTM handles it all from one place. Marketers can add tags without bothering developers, and you can set conditions like "only fire this tag when someone reaches the thank-you page." It keeps your site fast and your tracking organized.