Everyting You Need To Know About VAST

Apr 05, 2023

Almost all companies use videos to promote their product and increase sales. This kind of ad is quite effective if the promotion creator professionally designs it and qualitatively implements it in the digital strategy. But how advertisers could create an efficient video campaign? The answer is simple. They should use the modern capabilities of programmatic advertising!

And now we are here. At the stage where all advertising market players need to develop a unified solution for video ad serving in the world of hundreds of different video players built on different technologies. And here you need VAST.

Table of Contents

What is VAST?

VAST from Interactive Advertising Bureau, is a widely adopted advertising industry standard used in programmatic ecosystem elements [Ad Servers, SSP, etc.] and video players to display ads.

It is an XML file containing details required to execute the video advertisement, such as links to media files of different resolutions, other ad creative parameters, analytic provider’s code, event trackers, and so on.

The flow is simple: the publisher sends a request to an Ad Server or an SSP VAST tag and gets back a response. These responses are XML documents with the data we mentioned above [XML is a method for structuring and delivering information]. Afterward, the video player serves the ad to the user using the received data.

It is exactly why the IAB developed VAST. Its goal is to simplify and standardize the process of video ad serving. Furthermore, it helped to boost video ads market development.

Nowadays, you may find different video players for various portals and technologies (for example, HTML5, Flash, etc.) and many special media plug-ins on various mobile and home devices. All these developments do not have one standard language used to indicate ads. You know that this is HTML and JavaScript in browsers, but what about the players? How to tell the video player what clip it should play at a definite moment?

The IAB created VAST to make the code more standardized. VAST gives you data about the ad format, its location, and the URLs called during various events.

To apply this standard, it is essential to consider that VAST does not define all points of video ad delivery. For example, it could not provide any complex interactions between the advertising, the player, and the web page. The VAST template does not specify the place and time to show the ad because the video player and user make these decisions. However, VAST remains quite popular because its support is implemented using the Open Video Ads library in the majority of video players like JW Player and Flowplayer.

How Does Vast Work?

Let’s consider the exact process of using VAST for ad serving. The precise roadmap will look like this:

Step 1. Sending VAST Tag Request

In the first step video ad player sends a specific request. Depending on the ad serving model and player settings, it could happen when the user taps the ‘play’ or ‘pause’ button. The video player requests VAST from an Ad Server or SSP by calling a VAST tag.

An ad server provides a VAST tag as a URL. So it can look like this:


Step 2. Ad Server Is Processing Request

After the Ad server gets a request it uses tag parameters to collect information about the environment in which the potential advertisement will run on.

In the example above, we are saying that the ad is displaying on the publisher.org website; the video player size is 720 pixels wide and 440 pixels tall; the user’s IP address is 890.158.7.1.

These parameters are valuable pieces of data used for targeting, as well.

Step 3. Ad Server Is Returning VAST Response

The ad server will immediately return an XML VAST response file once it selects an ad. You can find more about its structure and contained data here. It is an IAB example. It can contain the next data that is needed to properly serve the video ad within VAST technology:

  • Pricing Model
  • Advertisers Info
  • Ad Category
  • Event Tracking Rules
  • Ad Duration
  • Creative ID
  • Media File Parameters

Step 4. The Video Player Is Playing an Ad

After the Ad Server sends a response, the publisher’s video player returns to the game! It plays the ad under the conditions received in the VAST Response.

Noteworthy is that the entire process can complete in less than 300ms. It is faster than the human blink!

VAST History and the Latest Updates

In 2008, the IAB showed the first version of VAST; then, the tag was improved and updated several times. After the success of version 1.0, which only supported MP4 videos, MOV, and 3GP formats, the following variants appeared:

  • VAST 2.0. The number of supported formats has increased, and new features have been added.
  • VAST 3.0. There was compliance with the standards of behavioral advertising and improved error reporting capabilities.
  • VAST 4.0. The main latest version with options for interactive advertising. There is support for CC and mezzanine files.

In November 2018, version 4.1 appeared, and a year later, in June, the developers created an improved version – 4.2. The last variant has the following updates:

  1. The list of VAST terms has been updated.
  2. The developer added a link to the “recent” macros list.
  3. Links to IconClickFallbackImage(s) have been fixed.
  4. There are creative resource files (for NonVideo and NonAudio).

Also, in the new version 4.2, users can add new macros even without a new variant of VAST at the next change. Another great update is the corrected HTML Resource example and description.

VAST & VPAID Difference

VPAID is also a development of the IAB organization. If you plan to show simple video ad formats, you don’t need this standard. It was created to eliminate the difficulties of incongruity between video players and ads including the ability to provide an interactive ad experience. So, VPAID makes those interactive add-ons possible without replacing the entire VAST setup. At some level, we may call VPAID and VAST as a proxy to each other whenever the situation calls.

The difference with VAST can be seen in the following:

VPAID allows interaction between ad video blocks and the video player; VAST builds a connection between the advertising server and the video player.

With VPAID, video blocks in video players can become interactive when an ad is expanded, or its tab is clicked. Using VAST only, you can serve just classic video ads.

With VPAID, a publisher can measure viewers’ relationship with advertising and track their actions; With VAST, the publisher can control the video player and specify instructions.

VPAID is an opportunity for video players to load a block with ads before displaying ads/media; VAST does not provide such a function.


Let’s summarize. We have already learned that VAST is an industry-proven technology providing a unified solution for serving video ads. Magic happens when the video player calls the VAST tag. Then there is an automated process of choosing a suitable ad, sending a VAST response, and reading certain elements of the XML document so the video player could finally serve the ad to the user. VAST and VPAID are necessary for efficient video advertising in the modern programmatic environment.

Contact us if you are interested in creating an effective video campaign. We will provide you with the best solution!

  • facebook
  • twitter
  • LinkedIn