Ad Request vs Bid Request

Purpose

This document distinguishes ad request from bid request, two terms that are often mixed together in ad platform discussions.

Key Takeaways

An ad request is a request from the publisher runtime environment to retrieve an ad.
A bid request is a request from an SSP or exchange to a DSP for bidding in an auction.
On the web, tags or scripts typically trigger the ad request; in apps and CTV, SDKs often do.
Distinguishing the two makes the roles of SDKs, SSPs, and DSPs much clearer.

Data Flow

Draft Structure

1. What is an ad request

It is triggered when an ad slot is loaded.
On the web, a tag or player script often sends it.
In apps, an SDK often sends it.

2. What is a bid request

It is the request sent to buyers for RTB transactions.
In the OpenRTB context, this object is the core auction request format.

3. Why the distinction matters

The runtime requester and the auction orchestrator are different layers.
SDKs typically do not auction directly with DSPs; SSPs usually orchestrate the bidding flow.

4. Practical notes

The runtime terminology differs by platform.
On the web, tag or script is often more precise than SDK.
In mobile apps and CTV, SDK is often the natural term.

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