Prebid.js is arguably the most popular header bidding platform in the ad tech space. It currently has the top spot in the header bidding market share, surpassing Amazon’s Transparent Ad Market. Prebid’s open source community, wide range of features, and many demand side sources make it a tantalizing choice amongst its competitors. This article briefly touches on Prebid’s origin story, its general architecture, and its future with SharedID and UnifiedID 2.0 (UID).

Prebid.js — An Origin Story

In its early days, programmatic digital advertising has been handled with a waterfall method. Publishers (known as “supply side” in ad tech) defined a list of advertisers (part of what constitutes the “demand side”) that were eligible to bid on available ad space (the supply is referred to as ad inventory). Inventory was then auctioned off in a sequential order, passed from one partner to another until it was sold. Since the first few partners in a chain could pass on the inventory, high latency could result. Moreover, the first advertiser in the chain to give an adequate bid did not promise the highest revenue.

Header bidding, also known as “advance bidding” or “pre-bidding”, was created as an alternative to this traditional structure. In header bidding, multiple demand sources like supply side platforms and exchanges simultaneously bid on available ad inventory. In doing so, publishers are able to maximize their revenue to the highest bidder. The auction is typically invoked in the head section of a page to help decrease latency issues (and its placement is the reason why the name is referred to as header bidding).

“Bidding” found on clearcode

Prebid.js was created in 2015 as a client side header bidding approach. Although there were many header bidding technologies available in the market, Prebid’s popularity grew and has been sustained due to a number of factors:

  1. Prebid.js technology remains widely accessible as it’s free and open source.
  2. The technology is flexible as it works well on both mobile and desktop, and with multiple formats which include display, native, and video.
  3. Prebid has a vast and supportive community. The Prebid committee often holds events with Q&A, and has a defined membership network to define and shape the technology of the industry.
  4. The technology is built and maintained in a way that allows for quick growth.
  5. Prebid.js has many attractive features such as analytics to track header bidding performance and multiple demand sources available to publishers.

General Architecture

The Prebid.js technology is composed of 3 parts: core wrapper code, analytic and bidder adapters, and modules. Each component provides a unique function to the Prebid.js library that allows publishers to configure and utilize features that suit them best without bloat.

The Prebid core handles initiating bid requests from multiple demand partners (partners bring advertiser demand to ad inventory supply) and running an auction on the publisher page. It is the minimum foundational code necessary to run header bidding and is touted as being lightweight and fast. While the core is required to use Prebid.js, the adapters and modules are optional and highly customizable.

There are two types of Prebid adapters: analytics and bidders. The analytics adapters are created and maintained by the respective analytic provider (e.g. Adagio analytics adapter is maintained by Adagio). When these plugins are used, they provide logistical data to the publisher. The bidder adapters represent the demand side partners that make bid requests. Similar to the analytic adapters, each bid adapter is created and maintained by the respective demand side partner (e.g. GumGum adapter is created and maintained by GumGum).

The third component of the Prebid technology are modules. Modules often provide extra functionality for publishers to integrate should they need it. Many modules are available to give publishers additional support which include consent management, currency conversion, and common User ID systems like SharedID and UID.

SharedID and UnifiedID 2.0

With the inevitable sunset of cookie matching, many companies have taken initiative to create frameworks that are self-reliant from third party cookies. The Prebid community in particular has taken steps to ensure a transparent, free, and open source real world identity solution. While Prebid.js offers integrations with many User ID systems that are alternatives to third party cookies, there are 2 modules in particular that are gaining traction in the Prebid community: SharedId and UnifiedId 2.0.

SharedID generates unique IDs to allow publishers to transmit first-party information to bidders (advertisers). Moreover, since SharedID is community driven, it can be used to create an ID for a certain subgroup’s interest called an audience segment. This audience segment is available for sharing with other publishers, hence the name SharedID. It is well used as over 17,000 publishers currently have integrated into it.

UID 2.0 is relatively new to the scene and is owned and operated by Prebid. UID was originally championed by The Trade Desk but recently made into an open source project earlier this year. Unlike SharedID, UID 2.0 is an email based approach. UID 2.0 requires users to directly provide consent to a publisher by providing their email address before a publisher can create an identifier.

Both identity solutions use first-party data to avoid the long process of cookie synchronization which can be expensive and lead to data leakage. They’re both open source and free. Although Google has since delayed ending support for third party cookies, the Prebid ecosystem has possible solutions to ensure there are alternatives to the future cookieless world.

Last Notes

Prebid has built a clean and feature rich technology by listening to their community’s concerns. As Prebid grows, GumGum continues to grow alongside with it. GumGum is regularly updating the adapter with features our partners and business teams desire. If you’re interested in adding Prebid to your digital advertising tech or have any feature requests, please feel free to contact us!

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