VAST — the Video Ad Serving Template — is the IAB Tech Lab XML specification that tells a video player what ad to play, where to fetch it, and which events to report back. VMAP sits alongside it describing where ad breaks fall in a piece of content.
VAST
VAST is how a video player and an ad server agree on what to play. The response describes the creative, its media files and the tracking events the player is expected to fire — impression, quartiles, completion — which makes it both a delivery format and a measurement contract.
- An XML response - Predates the industry’s move to JSON and persists because every player implements it.
- Tracking events in-band - Measurement is described in the same document as the creative.
- Wrappers and redirects - A VAST response can point at another, which is how supply chains stack — and where latency accumulates.
- VMAP for breaks - The companion specification describing ad break timing within content.
VAST is a useful reminder when reading agent-readiness scores: an industry can be thoroughly standardised at the message layer and still score poorly on published API contracts, because the two solve different problems. The State of Marketing & Advertising APIs measures the second, and the advertising segment’s 19.7 average reflects the absence of a discoverable interface rather than an absence of engineering.
Referenced in API Evangelist papers
This standard shows up in my published research. These reports read the machine-readable evidence provider by provider — and put this standard in the context of a real sector.
The State of Marketing & Advertising APIs
Standardised at the message layer since 2008 — evidence that deep industry standardisation and a published, discoverable API are different achievements.
