Glossary
What is In-app bidding?
Also called: app bidding, mediation bidding
In-app bidding lets ad networks bid on each app impression at the same time, so the highest bid can win instead of the first network in a fixed order.
हिंदी में पढ़ेंApps used to fill ads with a mediation waterfall, calling networks one by one in order of the average eCPM you set. Google’s AdMob help notes that the waterfall uses that average, not what a network will pay right now. So a network further down that would pay more for this user may never be asked.
With in-app bidding, networks bid on the impression in parallel, in a real-time auction. In AdMob, the bidding auction runs first and the winner is placed in the waterfall by its value, so the highest-valued source gets the first chance to serve. A bidder that loses is not called again in the waterfall. Most setups are hybrid, with bidding and waterfall sources in the same mediation group.
AdMob lists over twenty bidding partners, and Unity Ads no longer lets you create new waterfall placements. When you add a bidding partner, check that it also has a line in your app-ads.txt.
Example
Network A averages a $5 eCPM, so it is called first; Network B averages $3. For one user, A would fill at $2 and B would pay $8. In the waterfall, A fills at $2. With bidding, A bids $2, B bids $8 and B wins: $6 more CPM for that impression.
Why it matters to publishers
Bidding removes the cost of a fixed order and the wait through failed calls. Counting bidding sources against waterfall sources shows how much of your app still runs on old averages.