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# VAST (Video Ad Serving Template)
- URL: https://www.adlingo.org/glossary/vast/
- Published: 2025-01-15T09:11:00.000Z
- Updated: 2025-01-15T09:11:00.000Z
- Description: A script that provides information about which video ad to play, how the ad should play, and how it should be tracked.
- Author: Travis Lusk
- Tags: CTV, #glossary, #Import 2026-10-27 17:05

The protocol that tells a video player what ad to serve, when to serve it, how to track it, and what to do when something fails. VAST standardizes the communication between the ad server and the player. Without it, every publisher and player would implement video ad serving differently, and cross-publisher measurement would be impossible. Most CTV delivery still runs on VAST. Its limitations, particularly around interactivity and CTV-specific formats, are what VAST 4.0 and later versions are working to address.