Google Tag Manager

Google Tag Manager (GTM) is a free system that lets you manage and deploy marketing tags (snippets of code for analytics, tracking, etc.) on your website or app from one central place, without needing to edit your site's code directly for every change. You install one main GTM code snippet, and then use its interface to add, edit, and control other tags (like Google Analytics, Facebook Pixel) through "tags," "triggers" (when they fire), and "variables," saving time and improving flexibility for marketers.