Posted on Jul 14, 2023

Create Winning Video Ads with VAST Tags: A Step-by-Step Guide

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Before we start diving deep into the specification of VAST tags, let’s take a step back to understand how we can actually display video ads on a website. The first thing that comes to mind is probably an advertiser who uploads their video ad file somewhere on the server. Then they go to the website owner to negotiate the insertion of a video ad into the content (with a link in it).

These steps are correct but how does the advertiser find out how many people watched the video ad? How to find out if people watch it to the end or don’t watch it at all? Many questions arise after video ad placement. The answer to all these questions can be provided by VAST – Video Ad Serving Template. What is a VAST tag? Ad serving template VAST is a specification (XML schema) developed by the Interactive Advertising Bureau (IAB) that contains all information about ad media files: physical location, format (also VAST URL that will be called upon particular events, etc.). So, what is the VAST tag, how to create VAST tags, and what are their specifics and role?

VAST Tag: a brief history of video advertising standard

In the early days of digital video advertising, there were too many video ad players and video player developers. Some of these players were functioning based on Flash, the others on HTML5, also some of them required native applications, and the others certain plugins. Since then many websites removed flash videos and technologies changed.

Back in 2008, however, the players didn’t speak the same language and required a unified standard to display video ads. 

There was a lot of work on the ad server side. Additionally, there was no guarantee that the custom-coded video ads would correctly communicate with video players. The video ad code needed to be standardized so that video players would know which ads to play, and when. Later the industry developed VAST tags and VPAID standards to streamline ad creative rendering and serving across players and devices. 

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Why video ad serving template will still be popular in the future

It is hard to underestimate the impact of video advertising – since lockdown, it only grows in popularity because people spend more time indoors. Plus, video content streaming becomes convenient on any type of gadget, no matter mobile, desktop, or SmartTV. 

There’s nothing like the video advertising ad unit that сan tell a meaningful brand story or showcase the product in slight detail. The video media file can be also engaging.

In fact, 73% of people reported that they wanted to buy the product after watching the video ad. Marketers and advertisers, in their turn, also claim to receive higher ROI out of video ad serving. 

In the future, ad spending in video advertising is poised to reach $35 billion by 2024, whereas now it already accounts for $26 billion. So far VAST tags along with VPAID are the only standards that ensure smooth and good quality VAST ads delivery in video content. 

Plus, XML data contained in the VAST provides additional information which is very convenient for the advertisers when they measure the ad performance. This way, regardless of the publisher’s ad network or server, advertisers can run and measure their ads while ensuring that the publisher’s video player understands VAST.

Is VAST tag only for video ads?

Ads can be served onto multiple ad inventories within many kinds of video ad players. This way video ads appear in the proper format across different websites and ad networks. But is VAST only created for video format? A VAST tag URL can be applicable for serving both video and audio ads. Thus, it is suitable for multiple ads. Beyond traditional video formats, the audio VAST tag offers advertisers a unique avenue to engage audiences through immersive sound experiences.

By VAST tag definition, most frequently it is used for displaying video ads (pre, mid, post rolls) because video ads naturally fit into the video content on the website.

smarthub how to create vast tags

However, there are different kinds of VAST ads. 

  • Companion ads. These are the display ads, text, or rich media that typically appear around or alongside the video player. 
  • In-line ads. In-Line ads are served through the VAST protocol that has all the necessary elements so that the visual experience of the ad is boosted in the video content.
  • Linear Video Ads. These ads are like TV commercials. The linear ad requires the player to interrupt content playback in order to serve the ad. As a rule, those are pre, mid and post-roll ad formats. 
  • Overlays. These are ads that pop up as text or image excerpts, they are located over the main video and go along with it without interrupting playback.
  • Joint banners. Joint banners are displayed on a web page outside of the video player. As a rule, they are triggered by certain events, like mouse hover, etc. 

To ensure seamless ad delivery across various platforms, it’s crucial to integrate banner supply with js tags, optimizing the user experience and ad performance.

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The anatomy of VAST tags: their role, functions, and how they work

As we already discovered, VAST stands for video ad serving template. It was developed by the Interactive Advertising Bureau as a framework that embeds third party video ads into a video stream. It is a Video Ad Serving Template for structuring ad tags that serve ads to video players. VAST was designed to facilitate and standardize communication between video players and ad servers. 

What are VAST tags in more precise terms? 

The VAST tag is a script that uses the XML schema to transfer the metadata from the ad server to a video player on the publisher’s side. 

After VAST transfers metadata from the master video ad slot on the ad server, the VAST tag can program the video player so that it can show the ad creative on different sites and devices (mobile devices, desktops, and tablets) in a way that guarantees seamless rendering.

In the nutshell, a VAST tag can instruct a video player on:

  • Which video ad to play;
  • How long the video ads should last;
  • How to play video ads;
  • If users can skip any of the shown ads;
  • Where users will go after clicking on the video ad;
  • Where the player should fetch the video ad from (ad server);
  • What should be the click-through URL;

Thus, ad serving template VAST is the main link between advertisers and site owners. It represents a language thanks to which the ad tag can communicate with the ad server. Thanks to this advertisers serve VAST ads effectively and publishers effectively monetize video ad inventory. For businesses looking to maintain their brand identity while leveraging advanced ad technologies, a white-label ad operation team can provide tailored solutions and expertise.

For newcomers to the industry, they often ask, what is sellers.json, to understand its importance in digital advertising.

How does VAST work on sites

It’s time to find out how VAST works on web pages. The process of ad insertion takes place in three stages:

1. VAST request. At this stage, the ad server receives a call to fetch the ad (that comes from the player on the website).

2. VAST response. The ad server sends the VAST inline response to the ad player. Such an inline response contains the media file as well as the necessary VAST URL (helps the advertiser to track the impressions). 

3. URL tracking. The video player initiates the URL tracking, which allows the advertiser to track impressions and assess the video ad performance. 

smarthub how VAST tags work

VAST tag and the tracking pixel

It is worth mentioning that VAST advertising protocol also facilitates the creation of tracking pixels, which, in their turn are used for registering additional impression parameters like frequency, click rate, etc. Plus, tracking ad performance on a deeper level becomes possible thanks to advanced tag options. An additional tag parameter can specify the ad type, length, duration of watching, and so on. 

VAST ad tags vs VPAID – the difference between the two

Just as VAST, VPAID is a video ad serving standard developed by IAB. It facilitates the interaction between ads and the video players, thereby providing favorable conditions for serving interactive ads. It also allows advertisers to record data about how users interact with digital video ads.

In simple terms, VPAID is a set of definitions applied to VAST that help creatives themselves (not ad server) interact with the video player. 

It works as so-called “interface addition” – a part of the ad unit, it delivers interactive elements (ad playback, skip, scroll, close, etc.), and also collects data about these interactions for advertisers.

VPAID uses the .SWF format to read elements such as images, GIFs, and other interactive elements (that only VPAID can read). However, for instance, sometimes it happens that the user’s video player can’t read the .SWF. In such a case, VPAID script is automatically overridden by the VAST script to ensure that the video ad appears on all compatible players.

That’s why answering the question of which is better – VAST tags or VPAID – can be tricky. Sure, whereas one advertiser may strive to serve an interactive video format with VPAID, focusing on interactivity doesn’t always get possible because of the limitation of the players. 

Playback errors and the risk to slow down the web page loading on mobile are other reasons why VAST often gets prioritized over VPAID.

smarthub about VAST and VPAID

4 Benefits of VAST tags


The benefit of executing video ads with VAST is in universality. Prior to the adoption of the latest version VAST 4.2, VAST had many limitations, for instance, the inability to support API integration for real-time impression evaluation. 


Moreover, there were inconsistencies in adherence to industry viewability standards prior to VAST 4.0 / 4.1 versions. On top of that, the media players were often unable to display the linear ad (General Linear error, request timeout for a VAST URI, etc).

 Ability to transfer the large arrays of media files

VAST 4.0 the majority of the problems were resolved and the benefits of vast tags are now pretty diverse. The 4.0 and later versions brought in such capacities as the ability to transfer the large arrays of media files – plus, now VAST transfers important metadata associated with ad (while providing good quality rendering on any device). 


Stream stitching or ad insertion in digital videos are also happening on ad server side. It also delivers universal ad IDs attributed to every ad (for ensuring brand safety and ad targeting). VAST tags now also support more interactive formats, advanced reporting, and the opportunity to validate VAST tags. 

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How to create VAST tags?

When it comes to tag type – there are several of them: ones based on VAST XML and URL VAST. However, if you choose between tag options, know that VAST XML is the most preferred format when both XML and URL are supported by your DSP. So, let’s review how to create VAST tags in case you don’t use Google ad manager.

Third party tools

You can use VAST tag generators to generate VAST tags. VAST tag generators are usually offered by video players as an additional feature. 

However, you need to make sure that video player that offers the VAST tag generator supports your specifications (to avoid potential errors in the ad display). 

How to create VAST tags through third party tools?

  • Choose a VAST tags generator (usually offered by video players as extended functionality). Check if this video player supports the required specification.
  • Follow the instructions provided by the player. 
  • Copy the ad tag

How to create VAST tags manually?

If you don’t use the Google ad manager and third party tools then you will be inserting VAST tag manually with pre defined parameters. For this, you will have to create a VAST script by editing the predefined parameters and combining them together to create a complete XML file. Pre defined parameters can make it way easier to create vast tags compared to coding a new file completely from scratch. A complete example of it you can see below.

smarthub VAST script XML file

It is not recommended to create a VAST tag manually, because tools greatly simplify and optimize the process excluding the chance for potential errors. 

The above example showcases how the output looks like. After tag creation make sure you validate the output using the validation tool.

How to create VAST tag on SmartHub

When generating a new connection on the SmartHub platform, you can easily select connection type VAST and generate your VAST tag with the supported macros.  

how to create VAST tags on smarthub

The last word

Previously it was necessary to select third-party video ad servers that could support VAST tags insertion. These days advertisers often choose programmatic platforms where they can input the VAST tags and obtain detailed reporting and auditing of their ads as well as split testing tools. 

As video ads gain traction, SmartHub owners also need to incorporate video advertising into the media-trading environment. Just choose connection type VAST and generate your VAST tag with the supported macros. Note, that SmartHub also supports VAST to RTB, VAST to VAST and VAST to ALL media trading which helps partners trade with each other no matter the connection type. If you’re interested in learning more about the VAST protocol on SmartHub, check out how to vast for a comprehensive guide. This way your partners will be able to serve and monetize video content with no limitations or restrictions, which in turn will translate into greater opportunities and profits for you. 

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What are vast tags?
VAST tag, meaning Video Ad Serving Template tag, is standardized XML-based codes used in digital advertising. These tags provide instructions for ad display, including the ad creative, tracking events, and ad targeting information. By incorporating VAST tags into your video ad campaigns, you can ensure seamless delivery across various platforms and players, enhancing the reach and effectiveness of your advertisements.
What is the difference between vast and vpaid tags?
VAST tags handle the delivery and display of video ads, providing instructions for ad playback. On the other hand, VPAID (Video Player-Ad Interface Definition) tags offer enhanced interactivity by enabling ad interaction, such as clickable overlays and interactive elements within the video player. VPAID tags expand the capabilities of video ads beyond basic playback.
How do I test my vast tags before using them in a campaign?
To test your vast tags before using them in a campaign, you can set up a small-scale test by running a limited ad campaign or using a testing platform. Monitor the performance of the tags, analyze the data collected, and evaluate their effectiveness in reaching your campaign goals. Adjust and optimize as necessary before launching a full-scale campaign.
What are the common errors to watch out for when creating vast tags?
When creating VAST tags, watch out for common errors such as incorrect URL encoding, missing or invalid tracking URLs, mismatched or missing impression or click tracking macros, improper placement of ad elements, and incorrect or incomplete media file specifications. Testing and validating the tags thoroughly before deployment can help catch and fix these errors.
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