Breaking down the bid request and OpenRTB protocol
In programmatic advertising, the bid request is at the heart of every real-time auction. It’s packed with valuable information that helps marketers decide whether to bid on an impression and at what price. Let’s break down the elements of a bid request so you’ll have a better understanding of the OpenRTB protocol and how information is passed between parties to facilitate an ad auction.
What is OpenRTB?
As you may already know, programmatic advertising relies on standardized communication between different systems. At the core of this communication is a protocol called OpenRTB, or Open Real-Time Bidding. It’s the common language of ad tech.
In OpenRTB, bid requests and bid responses are formatted in JSON, or Javascript Object Notation, and consist of objects that are readable and easy to interpret, using key-value pairs enclosed in curly braces.
By providing a standardized way to express advertising-related information, OpenRTB allows media owners, marketers, and others in the programmatic supply chain—like SSPs and DSPs—to communicate during an auction. More importantly, it enables a more transparent bidding process, ensuring every participant in the supply chain has the information they need to make informed decisions.
When there’s an ad opportunity, SSPs send a bid request to DSPs. DSPs evaluate it and may send back a bid response. The DSP will quickly analyze data points like ad size, content type, audience data, and historical performance to decide whether to bid and at what price.
This entire process happens in milliseconds, allowing marketers to reach audiences efficiently and at scale, with relevant messaging, at the right price.
The DSP evaluates a number of attributes contained within the bid request. These attributes are expressed as structured data, as specified in the OpenRTB standard.
Let’s take a closer look at some key objects within a bid request.
The impression object
First up is the impression object, which describes the specific ad opportunity available.
This includes:
- Banner size for display ads
- Duration for video ads, or pod duration for an ad break consisting of multiple consecutive video ads
- The bid floor, which is the minimum price required to participate in the auction
The deal object
Bid requests may also include the deal object, which lives within the impression object, and details the parameters for pre-negotiated agreements between a buyer and seller. This might set fixed prices or provide premium inventory access.
These details help DSPs assess whether a given opportunity aligns with their campaign requirements.
Site and app objects
Next, we have the site or app objects, which provide information about the media owner and the property where the ad will appear. Ad opportunities on a website will use the site object, with fields for the site name and domain.
Requests for mobile or streaming app opportunities will use the app object and include the app name.
Content object
Within the site and app object is the content object. In environments like streaming, the content object can get very specific, sharing information such as:
- Genre
- Livestream status
- Content rating
- Language
- Channel or network
- Show-level data, like series name, season number, and episode title
This level of detail helps buyers place contextually relevant ads.
The device object
The device object offers essential information for addressability. It includes:
- Device type and operating system
- Geography
- IP address
- The identifier for advertising (IFA) for in-app environments
This information helps DSPs reach specific audiences and tailor creative formats for different screens.
The user object
The user object contains information about the consumer who’s viewing the ad opportunity. These fields use anonymized identifiers to allow buyers to reach relevant audiences while preserving privacy. If a universal ID is available, it will be included here, within the EID object. The user object may also contain information about the consent provided by a consumer for the processing of personal data.
The SupplyChain object
Finally, there’s the SupplyChain object, or schain, which shows the transaction path from the original media owner to the final buyer. This provides transparency by outlining all parties handling payment for the transaction.
Adopting industry standards ensures a stronger ecosystem
The OpenRTB protocol underpins programmatic advertising, providing a standardized way for all parties to communicate and fostering a transparent ecosystem. It continually evolves as the IAB Tech Lab releases new fields or attributes in bid requests to support the industry’s changing needs—for example, the OpenRTB 2.6 release introduced significant new features to support streaming TV.
It’s important for everyone in the supply path to implement the latest guidance to ensure consistent communication, accurate representation of inventory, and improved transparency.
Want to learn more about OpenRTB? See how the latest version, OpenRTB 2.6, enables new opportunities in streaming TV.
