If you recall, Google released the Google AdMob 6.0 SDK last week. It brought with it a number of new features and upgrades to the existing SDK. Overall, it was a great release, but Google has found that some people are confused over one of the new features - mediation IDs.
To help explain this new AdMob ID, the company has dedicated a post to the differences between the new mediation ID and the older publisher ID. It should help advertisers and developers better take advantage of both IDs to get the most out of AdMob.
A publisher ID comes about when you add a site/app to your account. The ID is used to request ads from the AdMob network. You can use a publisher ID to request banners and interstitials as well. While you can also use the same publisher ID throughout an application to get ads, Google suggests you use a different ID for each ad placement.
The mediation ID on the other hand is used for, what else, creating a mediation placement. It's used to retrieve the mediation configuration from the server so AdMob can get ads from other networks on your behalf. This ties into the big new feature of the AdMob 6.0 SDK that lets users pull ads from other networks into AdMob proper.
Mediation placements are very particular about the ads you place. You have to define the ad format or else the app will return an error. Even if the ads are the same size, you have to create multiple mediation placements for each banner and interstitial ad that you place.
Hopefully these tips will help those still working out all the new features in AdMob SDK 6.0. It's not that confusing once you get the hand of it. The new mediation IDs might throw you for a loop, but the simple tricks that Google supplied us with are sure to help.
If you find yourself still struggling with the new AdMob SDK, Google will be hosting a live Office Hours Hangout on the subject. These Hangouts are usually pretty enlightening. If you want to join the Hangout, it will be taking place on Wednesday, May 2, at 11 a.m. PDT (2 p.m. EST).