A mobile ad network is a company that collects ad space inside thousands of free apps and games, and sells it to advertisers as one large pool. An ad network is any business that gathers ad space from many publishers and resells it. A publisher is the owner of the app, website or channel where the ad appears. Mobile ad networks are a large part of the reason that so many apps in India are free to download.
A mobile ad network has two kinds of customer. The first kind is app makers who have ad slots to fill, such as the maker of a free-to-play mobile game. They add a small package of the network's code, called an SDK (software development kit), to their app. The SDK asks the network for an ad each time a slot comes up, for example between two levels of a game. The second kind of customer is advertisers. Many of them are app makers too, who want more people to install their own app.
App makers who advertise usually pay for each install. This price is called the CPI, cost per install. Imagine a new app that teaches spoken English to Hindi and Bhojpuri speakers, made by a start-up in Patna. It wants 1 lakh new users this month, and it agrees to pay ₹35 for each install. The network shows its video ad inside word games, cricket games and vernacular social media apps, to people whose phones are set to Hindi. A model predicts which viewers are most likely to install the app, and the network shows the ad mostly to them. For each install, the network collects ₹35 from the English app. Separately, it pays each game for the ads shown inside it, usually a price per thousand impressions, or showings. These prices are explained in impressions and CPM.
How does the network prove that an install came from its ad? A mobile measurement partner (MMP), an independent company, records which ad each new user tapped before installing the app. The advertiser pays only for the installs that the MMP confirms.
This check matters because of ad fraud. Some apps fake installs with racks of cheap phones, or claim credit for installs that would have happened anyway. Networks and MMPs look for warning signs, such as hundreds of installs from one device, or new users who open the app once and never again.
Many networks also sell their unsold space through an ad exchange, where other buyers can bid for it. Some add the places a phone has been, through location-based advertising.