Publisher / Site ID

A publisher / site ID is the unique code an ad network assigns to each website, app, or property in its supply, used to identify exactly where an ad ran. On native networks, every publisher that hosts a widget gets one or more site IDs, so spend, impressions, and conversions can be tracked back to the specific source.

How it works. When an ad placement serves an impression, the network records the site ID alongside the creative and click data. That ID, not the human-readable domain, is the canonical handle the platform uses internally. Advertisers see these IDs in their performance reports, sometimes masked or numeric, sometimes mapped to a readable publisher name.

Why it matters. Site IDs are the unit of site targeting. Because performance varies enormously from one publisher to the next, media buyers analyze results by site ID and then build whitelists and blacklists to concentrate budget on converting sources and cut wasteful ones. For competitive research, resolving site IDs to real domains reveals which publishers a competitor relies on, exposing proven inventory you can target. Some networks mask IDs to prevent exactly this kind of reverse-engineering, which is why click-trace and capture tooling that maps IDs back to named publishers is so valuable.