Programmatic · also called unified first-price auction, unified pricing
Unified auction
A unified auction is a single auction in which all demand sources, such as direct campaigns, header bidders and exchanges, compete for an impression under the same rules at the same time.
A unified auction puts everyone in one room. Instead of a waterfall, or a system in which one exchange gets special treatment, every eligible bidder (header bidding partners, the ad server's own exchange, server-side bidders and, in some systems, direct campaigns with a price) competes in one auction, and the highest bid wins.
The term is most associated with Google Ad Manager's 2019 move to a "unified first-price auction", which ended AdX's last look advantage and introduced unified pricing rules so the same floor applied to all buyers. Publishers had used header bidding precisely to force this kind of competition.
Unified does not automatically mean neutral: the auction's owner still sets the rules, sees all bids, and may apply fees differently. Those questions were part of the United States v. Google case. In mobile apps, in-app bidding provides a similar unified auction inside ad mediation platforms.
Think of it like this
A unified auction is like replacing a VIP entrance and a regular queue with one door where everyone shows their ticket at the same time.
An example
Prebid's best bid (US$2.60), an Open Bidding bid (US$2.40) and AdX (US$2.55) all enter the same first-price auction; the US$2.60 bid wins.
Related terms
Header bidding
Header bidding is a technique where a publisher offers each ad impression to many SSPs and exchanges simultaneously before calling its ad server, so all buyers compete at once.
First-price auction
A first-price auction is an auction in which the highest bidder wins and pays exactly what they bid, which is now the standard model in programmatic advertising.
Last look
Last look is an auction advantage in which one bidder sees the best competing bid before bidding, so it can win by bidding just slightly more.
Dynamic allocation
Dynamic allocation is a Google Ad Manager feature that lets Google's ad exchange compete in real time against a publisher's other non-guaranteed campaigns for each impression.
Waterfall (daisy-chaining)
A waterfall is an older way of selling ads in which an impression is offered to demand partners one at a time, in fixed priority order, until one fills it.