Server-side tagging (SST) is an approach to analytics and marketing tag management where data collection and forwarding logic runs on the publisher’s own server (or a cloud container), rather than executing JavaScript tags directly in the visitor’s browser. A typical setup uses a server-side Google Tag Manager container: the browser fires a single first-party request to the publisher’s subdomain, and the server-side container enriches and forwards events to third-party platforms such as GA4, Meta, or Google Ads. Benefits include improved data accuracy (fewer events blocked by ad blockers or browser restrictions), better performance (fewer third-party scripts executing client-side), reduced exposure to third-party cookie loss, and greater control over what data is shared with vendors. The trade-off is increased infrastructure cost and implementation complexity compared to traditional client-side tag management.