video ad serving BridTV
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Video Ad Serving Technology — VAST and VPAID Ad Tags Explained

VAST and VPAID ad tags BridTV

In our previous article, we’ve discussed video ad serving and how online advertisers can use it to get their ads out there. But we’ve also mentioned the invaluable role the introduction of VAST tags had for the online advertising industry. Now, we are going to expand upon that and take a better look at VAST ad tags. On top of that, we will introduce you to another video ad serving technology innovation — VPAID ad tags. These two are closely related but widely different, and that’s what we’re going to show you.

Let’s jump right in!


VAST Ad Tags

What Is a VAST Ad Tag?

VAST, also known as video ad serving template, is a script that facilitates coordination between an ad server and a video player. That way, the said player can roll an ad that it receives from an ad server and present it for the viewer. Everything we’ve mentioned applies to all types of devices — tablets, desktop, mobile, and more. 

As you can now see, the sole purpose of VAST ad tags is to make video players run ads to suit publishers’ needs. However, these tags don’t only serve ads — they can do so much more. The reason many publishers find VAST tags so convenient is that they can also offer insight into how those ads perform. So now you see how and why this video ad serving technology shaped the digital advertising market of today.

How Do VAST Ad Tags Work?

Here are 3-steps that all VAST tags must go through:

  1. Send an ad call request — the video player connects to the server and asks it to send an ad.
  2. Respond to the ad call — the ad server sends a response and the tracking URLs to the player that contains the necessary media files.
  3. Trigger the URLs — the video player accesses the received URLs to permit other parties to commence tracking measuring impressions.

As you can see, VAST tags are intermediaries in communication between the server and the video player. This process would have been much more tedious, were it not for VAST.

Are VAST Tags All-Powerful?

Unfortunately, the answer is no. Just like everything else in life, even VAST tags are flawed. Their benefits and uses are numerous, but they also have some limitations. That is especially true when compared to their VPAID counterparts. Here’s an overview of the pros and cons of VAST ad tags.


  • extremely popular ad tag format in the online advertising world — not hard to find support for it.
  • offers publishers significant control over their ad efforts — they can choose which ad to play, how to do it, the length of their ad, if the viewers will be able to skip it, etc.
  • automates the ad delivery process and reduces expenses while increasing revenue.
  • provides insight into ad performance and effectiveness.


  • although it offers information on ad performance, it’s outshined by VPAID in this department.
  • does not provide as interactive an experience as VPAID.


What Is a VPAID Ad Tag?

VPAID, also known as video player ad interface, is, just like VAST, a script that helps video players synchronize with ad networks. However, the similarities between the two end there.

Namely, VPAID ad tags offer advertisers an opportunity to serve interactive and creative video ads to the viewers — that is something VAST cannot do. But what do we mean by “interactive ads”? Well, here’s what using well-crafted VPAID ads gives your users access to:

  • clicking on different ad sections to open additional info
  • expanding the size of the ad at will
  • filling out fields or forms integrated into the add itself
  • taking a survey within the ad
  • interact with the elements in the ad itself or even play a minigame

Now you hopefully see what we meant with the “interactive” part.

Aside from the novelties in the interaction department, VPAID ad tags also record data on user interaction with the ads themselves. That information lets advertisers take different performance metrics into account and tweak their strategies accordingly.

How Do VPAID Ad Tags Work?

Similarly to the way VAST tags function, VPAID ad tags also follow several steps:

  1. Send an ad call request — this step is where the player makes an ad request from the ad server.
  2. Respond to the request — this part is when the server issues a response to the video player’s VAST XML file and the VPAID compliant ad unit.
  3. Communicate throughout — at this point, the player and the video ad unit continually exchange properties back and forth. 
  4. Track activities — finally, both the video player and the ad unit collect registered impressions and other similar data and forward it to their respective servers.

What Are the Limits of VPAID Ad Tags?

VPAID ad tags might have the edge over VAST, but they still have some limitations. Nevertheless, they are still one of the best ways for video advertisers to put their brand out there as these kinds of ads draw out the highest user engagement rates and drive the most conversions. Here’s a short list of pros and cons of VPAID ad tags:


  • the most interactive ad types out there
  • provide more detailed ad performance and user engagement metrics than VAST tags
  • have better conversion rates than VAST ad tags


  • their mobile inventory might be limited at times due to compatibility issues
  • can slow down page loading times and impact overall website performance
  • higher likelihood of errors occurring, which would make the ad fail to load
  • some players might not support VPAID tags yet due to it still being relatively new

VAST vs. VPAID — Which Is Better?

Considering that both VAST and VPAID are getting regular updates that increase the scopes of their capabilities, it’s hard to say which one will outshine the other. In their current state, they both have their pros and cons that we’ve stated, so it all boils down to your needs as an advertiser. 

If you are looking for a stable and easily accessible way to get your video ads to your users, VAST is probably the way to go. On the other hand, if you wish to drive more conversions and engage your viewers but don’t mind the downsides in reliability and accessibility that VPAID brings with it, give it a shot.

But in the end, you never know in which direction video ad serving technology will go in the future. So both of these ad tags might prove obsolete in just a few years from now! However, only the following is certain — currently, both VAST and VPAID give online advertisers a lot of perspective in their marketing campaigns, and we’re sure they’ll do the same with yours!