VAST, short for Video Ad Serving Template, is an advertising specification maintained by the IAB Tech Lab. It defines an XML response that tells a video player where to fetch an ad and which tracking URLs to call as playback progresses.
Think of three separate systems
- Your content video: the movie, clip, or episode the visitor came to watch.
- Your video player: the software that controls the viewing experience and decides whether and when to request an advertisement.
- MEDIARAZZI: the ad server delivering a VAST response with an ad creative, destinations, and tracking endpoints.
A VAST tag is a URL, commonly shaped like https://ads.mediarazzi.com/vast/YOUR_PUBLIC_KEY. When your player requests it, MEDIARAZZI returns XML with a <VAST> root, an <Ad>, <InLine> details, <MediaFile> addresses, and optional <VideoClicks> and tracking events.
Versions and compatibility
MEDIARAZZI currently emits a VAST 3.0 linear-video subset. The IAB specification has since advanced to VAST 4.x, including changes for modern connected TV and measurement. Do not imply that this server natively generates all VAST 4.x formats. Players supporting older VAST Inline formats may be compatible, but each integration must be tested.
One tag versus one ad
A single tag may point to one commercial, a rotating collection that selects one commercial on each request, or an Ad Pod with multiple commercials. Ad Pods need a player able to honor the sequence attribute.
Official references: IAB Tech Lab: VAST and VAST 4.3 specification.