Bid Requests and Bid Responses: a short guide


22 February 2023

Going deeper into media-buying methods, chances are that you soon run into the terms bid request and bid response. What are they, what do we need them for, and how does it all work? Let’s get it straight with the help of DecenterAds

The terminology

A bid request is a request for information sent by an ad exchange to potential buyers, such as demand-side platforms (DSPs), about the availability of advertising inventory. This request typically includes information about the user, the website, and the ad space being offered.

A bid response is a response sent by a buyer, such as a DSP, to the ad exchange in response to a bid request. The bid response includes information such as the buyer’s bid price for the ad inventory and any targeting criteria they have set.

What information does a bid request contain? 

A bid request typically contains information such as the user’s IP address and browser type, the website URL and its associated content, and the dimensions and format of the ad space being offered. This information is used by the buyer to determine if the ad inventory is a good fit for their campaign and to set their bid price accordingly.

What information goes into a bid response? 

A bid response usually includes the buyer’s bid price for the ad inventory, any targeting criteria they have set such as geographic location, demographics, or interests, and the actual ad creative to be displayed if the bid is successful.

How does bid “talk” work? 

When a bid request is received, the DSP uses algorithms to evaluate the inventory and decide whether it’s a good match for their client’s campaigns. If it is, they will send a bid response with their bid price and targeting criteria. The ad exchange then selects the highest bid and sends a notification to the winning buyer, who can then serve the ad to the user.

This whole process happens less that in a blink of an eye. Literally – you need around 300 ms to blink, but bidding only takes half of that time or less. Quite impressive! 

The way bid requests and responses work is standardized by special protocols – usually, the OpenRTB (Open Real-Time Bidding) protocol, created by the Interactive Advertising Bureau (IAB). OpenRTB regulates the communication between ad exchanges and buyers, and it is supported by most of the major players in the programmatic advertising ecosystem.

The latest version of OpenRTB is version 2.6, which was released in April 2022. It specifies new fields for the bid request and bid response, such as:

  • New user data fields, such as age and gender
  • New device data fields, such as screen size and operating system
  • New ad placement fields, such as position and format

Summing up

At the moment, bid requests and responses are quite important things in how the whole programmatic ad ecosystem works. The good news is that all of those vital elements are automated, so you will never have to deal with bid requests and responses manually. However, understanding how they work is crucial to be able to effectively navigate the programmatic landscape.

Have any questions on bid requests, bid responses, or other topics from the programmatic ad industry? Make sure to follow our blog and social media, where we regularly share interesting and important bits of information. And with any urgent queries, feel free to reach out to the DecenterAds support team! 



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