Ad Tag
An ad tag is a snippet of HTML or JavaScript code on a web page that requests an ad from an ad server and renders it in a specific slot.
An ad tag is a small piece of HTML or JavaScript code placed on a web page that requests an ad from an ad server and renders it inside a defined slot. When the page loads, the tag fires a call (the "ad request") containing details like the ad size, page URL, and any targeting parameters, and the server returns a creative to fill the space.
How it works: A publisher pastes the ad tag into the page template for each placement. On every page view, the tag sends an HTTP request to the Ad Server, which decides which ad to serve, runs any auction, and passes back the winning creative plus its tracking. The returned markup often contains a Tracking Pixel that logs the impression and click.
Why it matters: Ad tags are the connective tissue of programmatic delivery. A single tag can chain to multiple systems, with each handoff added or stripped along the Ad Supply Chain. Because tags reveal which servers, networks, and trackers a page calls, they are also a primary signal for ad-intelligence tools mapping who is really behind a placement. Native ad widgets use their own variant of an ad tag (a script tag with a publisher and widget ID) to load a feed of recommendations rather than a single banner.
Related terms: Ad Server, Tracking Pixel, and the Ad Supply Chain.
