Glossaryad networksad exchanges

Passback

passbackCPM floorad requestad serverinventory fill

In AdTech, a passback occurs when an ad network or ad exchange is unable to reach the publisher's floor CPM, or when no paid ads are available to deliver against a given request.

When this happens, the ad request is returned — or "passed back" — to the publisher's ad server, which can then route the request to another network in an attempt to fill the impression.

Ad Call
Also known as: ad request An ad call is a request sent from an ad slot on a web page or app to an AdTech platform — typically an ad exchange or ad server — for the purpose of serving an ad to the user. Ad calls usually…
Ad Server
A technological platform responsible for deciding which ads to display on a website, serving those ads, and collecting and reporting performance data such as impressions and clicks. Ad servers were among the first…
Ad Slot
An ad slot is the physical space on a webpage where ads appear. Publishers place ad slots in strategic locations across their site — typically areas where ad visibility and engagement are highest. Each ad slot contains…
Daisy Chain
Also known as: waterfalling, the publisher's waterfall A daisy chain is a media-buying process in which a publisher's ad server loads ad network, SSP, and ad exchange tags sequentially — one after another — until an ad…