Publisher

In advertising, a publisher is the owner of the space where ads appear. A newspaper website is a publisher. So is a blog, a mobile game, and, in search arbitrage, the operator who runs a content page or keyword lander showing ads from a search feed.

The publisher's job is to bring an audience and present ads to it. In return it is paid a revenue share by the ad platform. In search arbitrage the publisher usually has no organic audience of its own. It buys its visitors from a traffic source, which makes it a publisher and an advertiser at the same moment: an advertiser on Meta or Taboola, a publisher to Google or Microsoft.

That double role matters for policy. As a publisher the operator must follow the feed's rules, such as the AFS program policies. As an advertiser it must follow the traffic source's ad rules. Breaking either set can end the business, and the publisher is held responsible for the quality of every visitor it sends, whoever supplied them.

Think of it like this

A publisher is the landlord of a noticeboard. Advertisers pay to pin notices on it, and the landlord earns whenever a passer-by acts on one.