MRAID, or “Mobile Rich Media Ad Interface Definitions“, is the common API (Application Programming Interface) for mobile rich media ads that will run in mobile apps.
Without MRAID, serving rich media ads to a multitude of mobile apps, would be a very expensive and complicated marketing activity. Since most mobile apps are built to fit plenty of devices and written in diverse programming codes to run on several operating systems, advertisers would need to create a lot of rich media banners to fit the various requirements of mobile apps.
MRAID is actually the solution to this problem. The IAB (Interactive Advertising Bureau) established the MRAID to provide ad developers with a set of standard commands in API. The ad developers can use the commands to communicate with different mobile devices. This way they can run their rich media ads on different mobile devices without creating an individual banner for each device or operating system.