Audience Network Terminology

Because the online advertising industry uses many different words for the same concepts, it's worth defining how a few key terms are used in the Audience Network developer documentation.

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An image or video that is designed to help sell a product or to make an announcement.

Ad inventory

A collection of impressions. Despite the name, this is not a collection of ads.

Ad network

A company that both helps advertisers find available ad space and helps publishers find advertisers that are willing to pay the highest price for their ad space.

Ad space

The part of an app or website that is available to display ads to consumers.

Ad source

An entity that has ads that it wants to display in an app or website. This can be an ad network or an individual advertiser.

Ad unit

A UI container that you define in your app. This object defines the format, size, and other metadata for the type of ad that can be displayed.


A company that owns and wants to sell ads to promote a product or announcement.

See ad.

ARPDAU (average revenue per daily active user)

A metric that is used to measure the effectiveness of ads. ARPDAU is calculated as your total revenue over a 24-hour period divided by the number of active users of your product during the same period.


A bidding process that determines which ad source is willing to pay the most for an impression.



A single ad source that is bidding for an impression in an auction.


An advertising model in which a real-time auction between multiple ad sources decides which ad source will fill an impression. This model grew out of the header bidding model used by web pages.


CPM (cost per mille)

The amount that an advertiser pays to fill 1,000 impressions.


Historical CPM

The most recent CPM that a bidder paid for one of the publisher's impressions. In waterfall bidding, the historical CPM is used to determine which ad source should get the chance to fill an impression first.



This is what the advertiser is buying! This is a single opportunity to display an ad in one of your app's ad units.


See ad inventory.


Mediation partner

See ad network.


OpenRTB (Open Real-Time Bidding)

An internet protocol that is used in bidding. For more information, see the OpenRTB 3.0 specification.



An app or website that is owned by a publisher.


The owner of a property (an app or website). Publishers sell ad space to advertisers to generate revenue from their properties.


Remnant inventory

Leftover impressions that were not able to be sold directly.