What is VAST?
VAST or Video Ad Serving Template is an IAB specification that explains how video players communicate with ad servers, and serve ads.
When a video player has to play an ad, it sends a XML request to the VAST server which defines the following parameters: which ad media should be played, how (long) it should be played, and what information should be tracked as the ad is served.
VAST technology is important for advertisers and publishers as it allows them to automate and scale their advertising. Instead of publishers adapting to different ad technology, VAST bridges the gap by “translating” the language of ad servers to a language that video players can process and play the ad.
Most ads served with VAST are linear video ads (e.g. 15-second videos), and don’t support rich media and interactivity other than tracking click-throughs.
The most commonly used version of VAST is VAST 2.0, and one of the main disadvantages are problems with determining the viewability of an ad.
Due to shortcomings such as lack of interactivity and problems determining whether an ad is viewable, the advertising industry has crafted a different technology: VPAID.