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Video Ads (VAST & VPAID)

Video ads are advertising units played before, during, or after video content, delivered through industry standards like VAST that let any player render an ad from any server.

Updated 2025-07-06 Author Luc Dumont Reading time ~4 min

Key takeaways

  • Video ads run as pre-roll, mid-roll, or post-roll around content.
  • VAST is the core standard that lets any player serve any video ad.
  • VPAID (interactive) is largely deprecated; SIMID and OMID succeed it.
  • Server-side ad insertion (SSAI) stitches ads seamlessly, key to CTV.

VAST and the video standards

VAST (Video Ad Serving Template) is the IAB standard that describes how a video ad should be served and tracked, so any compliant player can render an ad from any ad server. VPAID added interactivity but caused performance and security problems and is being retired in favor of SIMID (interactivity) and OMID (measurement).

SSAI and CTV

In CTV, server-side ad insertion (SSAI) stitches ads directly into the content stream so they play seamlessly, like traditional TV, and resist ad blocking. SSAI is central to CTV delivery but complicates measurement, since the client-side signals digital measurement relies on are abstracted away.

At a glance
PlacementsPre-roll, mid-roll, post-roll
Core standardVAST (IAB)
InteractivitySIMID (VPAID deprecated)
CTV deliveryServer-side ad insertion (SSAI)

Frequently asked questions

What is VAST in video advertising?

VAST (Video Ad Serving Template) is the IAB standard that lets any compliant video player serve and track an ad from any ad server, making video ads interoperable across the ecosystem.

What is server-side ad insertion (SSAI)?

SSAI stitches ads directly into the video stream on the server so they play seamlessly and resist ad blocking. It's central to CTV but makes some client-side measurement harder.