Ad Mediation

The layer in an app's monetization stack that decides, per impression, which ad network gets to fill the slot at the highest price.

Your app has ad slots and several demand sources competing to fill them. A mediation platform sits between your app and those networks, running either a ranked waterfall or a live in-app bidding auction to pick the source that pays most for that specific impression. You integrate one SDK, connect your networks through it, and the mediation layer arbitrates. Google AdMob and Unity LevelPlay (formerly ironSource) are the platforms most publishers run.

Picture a puzzle game showing an interstitial between levels. On an old waterfall the slot is offered to networks in a fixed order until one accepts, often leaving money on the table. Move that slot to in-app bidding and every connected network bids in real time, so the impression goes to whoever values that exact user highest right then, lifting your effective revenue per thousand impressions.

A hybrid setup can quietly cannibalize itself. If you leave high-value networks stuck in a manual waterfall while others bid live, the bidders never get to compete against your best floors, and you lose the revenue mediation was supposed to capture. People bolt bidding on top of a legacy waterfall and never migrate the waterfall, so the two fight instead of cooperating.

Mediation only pays off if every source actually competes.