VAST: The Video Ad Serving Template is an XML response framework that enabled a consistent delivery format for ad across streaming video platforms.
Since It’s first launch back in 2008. IAB tech lab have made several updates which not only increase overall functionality but also increase simplicity to understand. VAST 2.0 which support VPAID JS media file format enable advertiser to serve the video ads across devices without any dependency on Flash. The latest version of VAST which is released by IAB is VAST4.0 ,
Separate video file and interactive file:
Video file and interactive portion of ad will load from different source, which will reduce the complexity of ad loading and its interaction counting.