History And Evolution: Comparison Of VAST 2.0, 3.0 And 4.0+ Versions

The video advertising market is changing rapidly. Users are increasingly watching content not only on smartphones and laptops, but also on Smart TVs, game consoles, set-top boxes, and OTT applications. At the same time, the demands on video quality, display stability, analytics transparency, and the security of the advertising environment are growing.

It is no longer enough for advertisers to simply show the video. It is important for them to understand exactly where the impression was, whether it was counted correctly, whether the user watched the video, whether the creative can be verified, and how advertising works in the CTV environment. It is equally important for publishers and streaming platforms to ensure stable playback, monitor ad loading, and maintain up-to-date partner requirements.

It is for this purpose that the IAB Tech Lab develops the VAST standard, the Video Ad Serving Template. Over the years, it has gone from a basic XML template for showing a video to a developed standard that supports complex tracking scenarios, high-quality video, interactivity, server-side ad insertion, and CTV inventory.

In this article, we'll look at how VAST versions have evolved, how VAST 2.0, 3.0, and 4.0+ differ, and why understanding these differences is especially important for video advertising campaigns in Eastern Europe.

In the early 2000s, video advertising developed in a fragmented manner. Each publisher, video player, or advertising platform could have its own ways of delivering videos, its own tracking mechanics, and its own technical requirements.

For advertisers, this meant scaling difficulties. The same video had to be adapted to different platforms, and the data on impressions and screenings was difficult to compare. This created a technical burden for publishers: they had to support different integration formats and constantly solve compatibility problems.

IAB and the IAB Tech Lab have begun to develop standards that allow market participants to work in a single coordinate system. One of these key standards is the VAST template, which describes how an advertising server should transmit video ads to the player.

The main idea of VAST is simple: the advertising server returns an XML document, and the player reads it and understands which video to download, which events to record, and where to send tracking signals.

Although VAST is an international standard, its practical implementation depends on the local market. There are various industry associations, national regulators, privacy requirements, and technical practices in Eastern European countries.

Local associations and industrial groups usually do not replace the IAB Tech Lab, but help to adapt international approaches to specific market conditions.

This may relate to several areas.

Regulation of advertising and data.
In EU countries, GDPR, ePrivacy, and user consent requirements apply. Countries outside the EU may have their own laws on personal data and digital advertising. This affects which identifiers can be transmitted, how third-party pixels work, and how consent signals should be processed.

Market infrastructure.
CTV, OTT, programmatic video, local SSP, DSP, ad servers, and verification systems are developed differently in different countries of the region. Therefore, the same VAST version can be implemented at different speeds.

Advertising purchase processes.
Direct deals with media groups play an important role in some markets, while programmatic and international advertising platforms play a major role in others. This affects the depth of Wrapper chains, tracking requirements, and the need to support new specifications.

Requirements of international advertisers.
Large brands increasingly expect transparent analytics, secure interactivity, UniversalAdId, Open Measurement, and compatibility with CTV inventory. This pushes the region's sites to upgrade their technology stack.

The first versions of VAST solved the main problem of the market: they provided a common language for interaction between the advertising server and the video player.

VAST 1.0 appeared as the basic version of the standard. It described the fundamental XML structure, allowed you to specify a media file and record the fact of being shown through Impression. This was an important step towards standardization, but there were still few opportunities for advanced tracking and flexible analytics.

VAST 2.0 has expanded the functionality. It now supports linear and non-linear formats, Companion Ads, and quartile events such as firstQuartile, midpoint, and thirdQuartile.

The key value of VAST 2.0 was that it became applicable for mass video advertising. Platforms have received a more understandable way to describe creatives, and advertisers have received a basic opportunity to measure not only the fact of an impression, but also the depth of viewing.

However, VAST 2.0 had limitations:

• Insufficient support for interactivity;
• Limited structure for complex CTV and OTT scenarios;
• Lack of Mezzanine for high-quality source files;
• Limited creative identification options;
• Fewer tools for verification and error protection.

VAST 2.0 can still be sufficient for simple pre-roll campaigns, especially when it comes to short videos and basic tracking. But for modern video cameras, especially in CTV and OTT, its capabilities are often no longer enough.

In order for the player to show a simple video clip, VAST must have a basic set of elements.

An example of a minimal VAST:

VAST 3.0 has become an important stage in the development of the standard. It expanded tracking capabilities, made working with skipped ads more understandable, and gave the market a convenient balance between functionality and relative ease of implementation.

Skipped ads
Support for skippable ads has become one of the key innovations. The skipoffset attribute allows you to specify the moment after which the user can skip the video.

For example, an ad may become skippable after 5 seconds or after a certain percentage of the duration. This gave advertisers and sites more flexibility: it was possible to create formats that irritate the user less and at the same time retain their advertising value.

Skip formats are especially important for analytics. They help you understand how quickly the user loses interest, which creatives hold your attention, and where to optimize the first seconds of the video.

Advanced tracking
VAST 3.0 has consolidated a more advanced event system:

• start;
• firstQuartile;
• midpoint;
• thirdQuartile;
• complete;
• pause;
• resume;
• mute;
• unmute;
• fullscreen;
• skip.

These events allow you to analyze not only the fact of the display itself, but also the user's behavior during viewing.

For example, if a video is often skipped immediately after the Skip button appears, this may indicate a weak beginning of the creative. If users watch the video to the end but don't click, there may be a problem with the CTA or landing page relevance.

Flexible monetization
VAST 3.0 has also become a convenient standard for publishers and adtech platforms. It allowed you to set up different display scenarios: unreleased videos, skippable ads, mid-roll placements, additional tracking events, and custom extensions via <Extensions>.

VAST 3.0 has long remained a practical compromise for the Eastern European markets: it provides sufficient analytics depth, supports common advertising scenarios, and does not require such a large-scale infrastructure overhaul as the transition to VAST 4.x.

VAST 4.0 has become a serious step forward. While VAST 2.0 and 3.0 mainly solved the tasks of video delivery and basic tracking, VAST 4.x is focused on a more mature video advertising ecosystem.

In the center of attention were:

• High quality video;
• CTV and OTT;
• Server-side ad insertion;
• Secure interactivity;
• Identification of creatives;
• Verification;
• Brand safety;
• Compatible with global advertising requirements.

Mezzanine: the path to high-quality video
One of the key innovations of VAST 4.x is the support for the <Mezzanine> element.

In previous versions, the advertiser or platform could specify multiple <mediafile> with different resolutions and bitrates. But these versions of the video often had to be prepared manually in advance.

<Mezzanine> solves this problem differently. It allows you to specify a high-quality source video file, which can then be transcoded to suit different devices, screens, and playback conditions.

This is especially important for OTT and CTV, where users watch content on large screens and expect high-quality images.

Advantages of Mezzanine:

• Convenient operation with Full HD, 4K and higher resolutions;
• The ability to automatically adapt to different devices;
• Less manual preparation of different versions of the video;
• Better compatibility with SSAI providers;
• More stable quality in premium video equipment.

This is especially true for Eastern European media groups, streaming services, and CTV platforms: the Smart TV market is developing, and advertisers are increasingly expecting quality comparable to television placement.



UniversalAdId: unified identification of creatives
Another important element of VAST 4.x is <UniversalAdId>.

It allows you to assign a unique identifier to the commercial, which helps all participants in the chain understand which creative was shown.

UniversalAdId solves several tasks:

1. Unified accounting. An advertiser, agency, ad server, SSP, DSP, and publisher can compare data on the same creative.
2. Creative control. The risk of a situation where another file is shown instead of the agreed video is reduced.
3. Brand safety. The brand gets more control over which creatives are launched and where they are reproduced.
4. Anti-fraud. Unique identification makes it more difficult to substitute a creative and helps to more accurately audit advertising impressions.

UniversalAdId is especially important for international campaigns in Eastern Europe. When one brand launches videos in several countries in the region, a single identification helps link campaigns, creatives, and reporting into one clear system.



Interactivity: the transition from VPAID to SIMID
For a long time, VPAID was used for interactive video advertising. It allowed the creative to interact with the player and create more complex formats: buttons, shapes, overlays, interactive scenarios.

But VPAID had a serious drawback: the creative got too much access to the logic of the player. This could lead to crashes, security issues, increased latency, and verification difficulties.

SIMID, the Secure Interactive Media Interface Definition, has been proposed as a more secure alternative. In this model, the interactive creative does not directly control the player. It works in a more controlled environment and sends requests to the player to perform certain actions.

Advantages of SIMID:

• Higher security;
• Less risk of playback failure;
• Better player control;
• The interaction between the creative and the application is clearer;
• It is better suited for CTV and OTT environments.

For Eastern Europe, the transition from VPAID to SIMID is gradual. Many sites still use VPAID or HTML5 mechanics because they are already built into existing processes. But for CTV, premium video, and international advertising campaigns, SIMID is becoming an increasingly important reference point.



VAST 4.x and SIMID usage in Eastern Europe
The level of VAST 4.x adoption is not uniform in the Eastern European markets. Major streaming services, CTV platforms, media groups, and technology partners are moving faster towards new specifications because they need quality, security, and compatibility with international requirements.

The main reasons for switching to VAST 4.x:
Demand for high quality. Users of Smart TV and OTT services expect high-quality images. Mezzanine support and correct work with adaptive video help ensure stable playback.
International integration. Global advertisers and agencies are increasingly demanding transparent identification of creatives, verification support, and a clear tracking structure.

CTV-monetization. CTV inventory usually costs more than classic web video, so higher demands are placed on the quality of the display and analytics.

Brand safety and the fight against fraud. The more budgets are spent on video and CTV, the more important it becomes to check creatives, verify impressions, and protect against incorrect placements.

At the same time, there is no complete transition to VAST 4.x in the entire region yet. Many players continue to use VAST 2.0 or 3.0 for practical reasons:

• Existing SDKs and players are already configured for older versions.;
• Upgrading the infrastructure requires resources;
• Not all sites have a high share of the CTV audience.;
• VAST 3.0 is sufficient for basic pre-roll campaigns;
• Not all partners in the advertising chain are ready for VAST 4.x.

Therefore, the market is evolving evolutionarily: large players are introducing new elements faster, and medium-sized and small sites often move gradually, starting with individual functions.

CTV has become one of the fastest growing video advertising segments. Users are increasingly watching content on Smart TVs, set-top boxes, game consoles, and streaming service apps.

CTV is different from classic web video. There are different devices, different user scenarios, a different level of quality expectations, and a different technological architecture.

On the web, the player often directly calls tracking URLs from the browser. In CTV and OTT, things are more complicated: some ads can be inserted on the server side via SSAI, and the devices themselves may have limitations on the SDK, viewability measurement, and third-party code execution.

Therefore, the IAB Tech Lab has released the CTV Addendum 2024, an additional guide that clarifies the use of VAST in Connected TV and Advanced TV environments.



What's Important in the CTV Addendum 2024
SSAI support
SSAI, a Server-Side Ad Insertion, allows you to insert ads into a video stream on the server side. For the user, the advertisement looks like part of a single stream, which reduces the risk of buffering and improves playback.

But SSAI complicates the measurement. If the player does not load ads directly, you need to think separately about how to capture impressions, screening events, errors, and viewability.

The CTV Addendum helps to describe how to apply VAST in such scenarios and how to maintain measurement transparency.

Open Measurement
Open Measurement is important for independent verification of advertising. In a CTV environment, measuring viewability and other parameters is more difficult than in a browser, so a standardized approach to measurement is especially important.

For advertisers, this means more trust in data, and for platforms, the opportunity to sell inventory at a higher price due to transparency.

UniversalAdId
The CTV Addendum further highlights the role of UniversalAdId. With the big screen and premium video, it's important to know exactly which creative was shown, especially if the campaign is running in several markets and through several technology partners at once.

SIMID instead of VPAID
For CTV, interactivity must be safe and controlled. VPAID is poorly suited for such environments due to performance and security risks. SIMID offers a more predictable model of interaction between the creative and the player.

Mezzanine and video quality
CTV inventory requires high quality. The Addendum reinforces the importance of high-quality sources, correct transcoding and adaptation to different devices.

Labeling and regulatory requirements
Different countries in Eastern Europe may have different rules for disclosure of advertising information, data processing, and user consent. Therefore, it is important that the VAST structure and related extensions allow you to correctly transmit the necessary parameters for compliance, reporting, and the user interface.



The value of the CTV Addendum for Eastern Europe
For the Eastern European markets, the CTV Addendum 2024 is important for several reasons.

The growth of Smart TV and OTT.
The audience is increasingly watching long video content on large screens. This makes CTV one of the most attractive segments for advertisers.

Increase the premium video inventory.
Streaming services and media groups are developing their own applications, advertising products, and programmatic integrations.

Requirements of international brands.
Global advertisers want clear metrics, independent verification, and uniform quality standards.

Heterogeneity of the region.
Different countries have different levels of CTV maturity, different local platforms, different regulatory conditions, and different integration opportunities. Therefore, the Addendum may not be implemented all at once, but in stages.

In practice, many companies start with individual elements: improving the VAST structure, implementing UniversalAdId, configuring Open Measurement, reducing Wrapper chains, or preparing for SIMID.

A full transition to all the recommendations of the CTV Addendum requires coordination between players, ad servers, SSPs, DSPs, SSAI providers, verification systems, and application owners. Therefore, the process usually takes time.

At first glance, it may seem that after the appearance of a new version of the standard, all market participants should quickly switch to it. In practice, VAST 2.0, VAST 3.0, and VAST 4.x continue to coexist.

There are several reasons.
1. Existing infrastructure

Many companies have been building their advertising systems on VAST 2.0 or 3.0 for years. This applies to players, ad servers, SDKs, reporting, analytics, and internal processes.

Upgrading to a new version doesn't just mean updating XML. You often need to change the tag processing logic, test players, check tracking, adapt partner integrations, and train teams.

Therefore, some players adhere to a pragmatic approach: if the current version is stable and closes business tasks, the transition is postponed.

2. Limited business requirements
Not everyone needs Mezzanine, SIMID, UniversalAdId, or complex CTV scripts.

If the site mainly shows short videos on the web or mobile environment, and impression, quartile tracking and click tracking are enough for advertisers, then VAST 3.0 may be quite sufficient.

In this case, upgrading to VAST 4.x may not have an immediate commercial effect.

3. Different levels of market maturity
In Eastern Europe, digital advertising markets are developing unevenly. In some places, CTV has already become an important channel, while in others, the bulk of video advertising still falls on the web and mobile.

Therefore, the demand for VAST 4.x and CTV Addendum is higher where there is a developed premium video inventory, international advertisers and programmatic videos.

4. Evolution instead of sudden migration
The IAB Tech Lab is developing the standard gradually. New features can be implemented in stages, including through <Extensions>.

This allows the market not to break existing integrations, but to add the necessary functions gradually: first UniversalAdId, then improved measurement, then SIMID, then extended CTV scenarios.

5. Dependence on partner chains
Video advertising often passes through several participants: publisher, SSP, DSP, ad server, verification partner, SSAI provider.

If at least one link supports only VAST 3.0, the entire chain may be forced to work within this version. Updating one participant without syncing with the others can lead to errors, loss of tracking, or incorrect playback.

If you are working with simple web video campaigns, VAST 3.0 will often be sufficient. It supports major events, skip formats, and is understandable to most partners.

If you are developing CTV or OTT inventory, you should focus on VAST 4.x and study CTV Addendum 2024. This will help you prepare for premium video requirements in advance.

If you work with international advertisers, pay attention to UniversalAdId, Open Measurement, correct verification and transparent tracking structure.

If interactivity is important, it is better to plan the transition from VPAID to SIMID. This is a safer model for modern players and CTV environments.

If you use Wrapper chains, control their depth. The more levels, the higher the latency and the risk of errors.

If you are launching campaigns in several Eastern European countries, check privacy requirements, consent management, landing localization, redirects, and tracking pixel compatibility in advance.

VAST has come a long way: from a simple XML template for video delivery to a mature standard that supports CTV, OTT, high-quality video, sophisticated analytics, secure interactivity, and global creative identification.

VAST 2.0 laid the foundation for the standardization of video advertising.
VAST 3.0 added advanced tracking and skip formats and has become a practical standard for many campaigns.
VAST 4.x brought the standard to the level of modern requirements: Mezzanine, UniversalAdId, SSAI, SIMID, verification and CTV scenarios.
The CTV Addendum 2024 clarified how to apply VAST in Connected TV and Advanced TV environments.

For the Eastern European markets, the key challenge lies not only in choosing the VAST version, but also in the right implementation strategy. Somewhere VAST 3.0 is enough, and somewhere VAST 4.x, Open Measurement and CTV Addendum support are already needed.

Understanding VAST's evolution helps advertisers, publishers, and technology teams make more precise decisions: which features to implement now, which to leave for the next stage, and how to build an infrastructure ready for further growth in video advertising.