GTM

GTM - Google Tag Manager, tag management system. You put one JS snippet (container) on the site, and then all the pixels, counters and analytical scripts - VK Pixel, GA4, Yandex Metrica, Facebook Pixel, calltracking - are added and configured through the GTM interface without contacting the developer.

The main practical gain is speed. Without GTM, adding a new pixel is a task in Jira, a sprint, deployment, a week of waiting. With GTM, this is 15 minutes in the interface and a “Publish” button. This is critical in quick tests: I launched a campaign, realized that a conversion event was missing, and corrected it right away.

GTM works through three entities: tags (what to run), triggers (when to run), variables (what data to transfer). For example: tag “VK Pixel - Lead”, trigger “form with ID=lead-form submitted”, variable “order amount from dataLayer”. A properly configured dataLayer is the basis for accurate end-to-end analytics.

The main mistake when working with GTM is publishing changes without testing in Preview mode. One wrong trigger can duplicate all conversion events, and ROAS in the account will become twice as beautiful as in reality. I always check GTM Preview + DebugView in GA4 before publishing.