An interstitial ad is “a full screen ad that covers the interface of its host application”. Or in layman’s terms, it’s a full-screen ad that displays within a mobile application.
Interstitial ads usually pop up at transition points, such as a pause between levels within a mobile game. Users have the choice of clicking on the interstitial ad, or closing it and returning to the application.
Interstitial ads are one of the most effective types of mobile ad, because of their large size and direct Call-to-Action. Over the past few years, they’ve proven themselves engaging and profitable. However, it should be noted that their size requires more data and bandwidth than traditional banner ads.