Google Tag Manager

You install one container snippet on the site. In the GTM dashboard you then define tags (the scripts to run, such as GA4, Google Ads, the Meta Pixel or LinkedIn's Insight Tag), triggers (when to run them: page views, clicks, form submissions, custom events) and variables. The site's own code can push events and details, such as an order total, into a data layer that tags read. Changes are published as versions, with a preview mode for testing first.

It frees marketers from waiting on developers, but every tag adds third-party JavaScript that can slow pages, leak data or break things, so access and reviews matter. It works with Consent Mode and cookie banners to hold tags back until a visitor agrees. Server-side tagging runs a container on a server you control, which receives events from the site and forwards them to each vendor, so fewer scripts load in the browser and you decide what is shared.