Ad tags are snippets of codes placed by publishers on their sites for ad serving. What more an ad tag can do? How it helps with targeting? Get answers here.

‘Ad tag’ as a term is used a lot in the ad tech industry. Usually, it is known to be the code involved in serving the ad creative. However, that’s not it. Ad tag is much more than just a snippet of code.

Let’s look closely to understand the ad tag.

What are Ad Tags?

An ad tag is a piece of code (HTML or JavaScript) that is placed on the publisher’s website to display ads. Ad tags are placeholders for the ad creatives on the publisher’s site.

These tags contain the details of the size, format, and other requirements of the ad unit. Ad tag serves different purposes for different parties (advertisers, ad networks, ad servers, and third-party services).

  • For publishers, placing an ad tag make their inventory available for sale.
  • Advertisers use these ad tags to send creatives for available impressions.
  • Ad servers use these ad tags to move ad calls along to the next step in the inventory exchange chain who then send out Request for Bid (RFB).
  • Third-party services (like data management platforms) use ad tags to extract user’s information and to create an elaborate user’s profile.

An ad tag is responsible for generating the bid request, which is passed on to advertisers and agencies (from the ad server), informing them about the user and his parameters so that the desired ad can be served from the advertiser end via DSP.

How Does An Ad Tag Work?

How do ad tags work

  1. When a user opens a publisher’s site, an ad tag code is called and a signal is sent to the ad server to find a suitable creative.

  2. Based on the dimensions and format of the creative, a bid request is sent to the data provider to get further details (geolocation, age, gender, etc.) of for user targeting purposes. This is followed by the data provider returning the request with desired user detail to the ad server.

  3. The ad server then forwards the request to the advertisers. Based on the publisher-advertiser transaction relationship, the mode of buying is decided. For instance, if they have a programmatic guaranteed deal then the bid will go to the advertiser who was guaranteed a certain number of impressions by publishers (no DMP will be involved in this case). Post this, the advertiser will send creative to the ad server.

  4. Finally, the ad server places the creative on the user’s browser, returning the ad tag with creative URL.

Types of Ad Tags Publishers Should Know

  1. Asynchronous ad tag: These are third-party ad tags that load independently on web browser, without affecting the page load time of a website.

2. Synchronous ad tag: These ad tags load together with the web content and affect DOM rendering. If synchronous tag or code is rejected, then it will be stuck in a loop calling synchronous tag over and over again, affecting the load time of the rest of the content.

In order to reduce the page load time, asynchronous ad tags are preferred over the synchronous ones. Google Adsense, by default, lets the publishers add asynchronous code to their site. However, publishers can choose to use synchronous ad tag, if they want.

Here is an ad tag example of the AdSense code containing synchronous and asynchronous ad tag:

Asynchronous and Synchronous ad tag

What Does an Ad Tag Look Like?

Here’s the structure of DoubleClick ad tag along with the most commonly used key-value pairs:

By looking at this ad tag, you can tell a lot about its working. Let’s break it down in pieces to understand. Here, you can see, the ad server, DoubleClick is hosting the service for the publisher.

ADJ/: It calls the specific ad type/format requested by the ad unit. ‘ADJ’ is for image or XML files.

publisher/: This is where a publisher’s identity is verified. DoubleClick checks whether the ‘publisher’ is part of DoubleClick network or not, to further provide the services.

zone/: It lets a publisher target user with granularity. Zone level specifications likely to attract different advertisers.

topic=abc: It’s the first targeting point. It can be anything. For the sake of an example, suppose, the topic here is ‘sports’.

sbtpc=def: Or Subtopic. This is to further categorize the required creative. Continuing with the above example, ‘badminton’ is the sport ad unit requires.

kw=xyz: Keyword for the required creative. Also, multiple keywords are also allowed. Let’s assume the required keywords are ‘badminton’ and ‘badminton equipment’.

tile=1: This variable is given a unique value for each ad call on a specific page. If there is more than one tile with the same value, then the same ad will be displayed on them.

slot=728×90.1: This is to give order to the ad slots. Suppose there are two-leaderboard (728×90) ad units on a page, then these ad units will be assigning them numbers (like 728×90.1 and 728×90.2).

sz=728×90: This simply tells the size of the ad unit. Here the ad unit size is 728×90 or a leaderboard.

ord=7268140825331981: A randomly generated number for cache-buster purpose. A user is supposed to move back and forth on various web pages. Hence the idea is to show him/her a different creative each time. To prevent the browser from showing the same ad rendered from the browser cache, a random number is assigned to ad tag in order to get a unique view from the user.


1. What Is an Ad Tag?

The third party ad tags, also known as creative tags or placement tags, are pieces of source code that, when inserted into a page, send a request to the ad server for the ad to be served.

2. What does an Ad Tag Look Like?

A modern digital ad tag is encoded in JavaScript code and consists of a URL that a browser uses to retrieve the ad’s content and placement information.

3. What is ad tag URL?

Video and audio ads are retrieved by players using VAST ad tag URLs. Using the parameters below, you can manually assemble a VAST ad tag URL or modify an existing URL, and then test it using the VAST suite inspector. These sample tags can also be used for review and testing. Both HTTP and HTTPS are supported by VAST ad tags.


Shubham is a digital marketer with rich experience working in the advertisement technology industry. He has vast experience in the programmatic industry, driving business strategy and scaling functions including but not limited to growth and marketing, Operations, process optimization, and Sales.

1 Comment

  1. David Wong Reply

    Sounds great as usual, Your way of explanation about adtag is simple awesome, someone without adops knowledge will also understand your stuff.

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