Table of Contents
Overview
Real-time bidding (RTB) is a method of transferring media that allows individual ad impressions to be bid on in real time via an auction. OpenRTB is an open industry standard format for bid requests and responses that allows for efficient and transparent facilitation of ad auctions.
How Real-Time Bidding Works
Supply Side Platforms (SSPs), also known as inventory sources, generate bid requests when a publisher wishes to fill an impression. Bids on those requests are submitted by Demand Side Platforms (DSPs) and the winning bid is decided by the SSP. The corresponding advertisement for the winning bid is served to the browser or app that triggered the bid request.
DSPs can have integrations with multiple inventory sources to allow them to buy media programmatically from a wide variety of publishers. In order to transact with the inventory source, the DSP needs to understand how to read that given inventory source’s bid request object and also respond in a way that the inventory source can interpret. For this reason, the IAB released a standardized method for structuring bid requests which allows platforms to integrate more easily. These protocol standards, called OpenRTB, aim to simplify the connection between suppliers of publisher inventory (such as exchanges or SSPs) and the buyers (such as bidders or DSPs).
FreeWheel DSP generally supports OpenRTB 2.3, but in some cases, fields from OpenRTB 2.5 and 2.6 are supported.
OpenRTB Basics
- The base of the protocol between an exchange and its bidder is HTTP
- JSON is the suggested format for bid request and bid response data payloads
- RTB transactions are initiated when an exchange or other supply source sends a bid request to a bidder
- Attributes are “required” if their omission would technically break the protocol
- Some optional attributes are denoted “recommended” due to their elevated business importance
Bid Requests
- The top-level bid request object contains a globally unique bid request or auction ID
- Must have at least one impression object
- id and imp (impression) are required objects
- Bid Requests can also include additional objects that provide more information for the buyer, such as the site or app name
Bid Response
- RTB responses contain bids that reference specific impressions within a bid request
- An empty HTTP response constitutes a no-bid
- A bid response may contain bids from multiple “seats” or from the same “seat”. A seat generally corresponds to a customer of the DSP.
- Objects in a Bid Response include: BidResponse, SeatBid, Bid
Summary of Previous Versions
- OpenRTB 2.0 provided unified support for display, mobile, and video capabilities
- OpenRTB 2.1 provided improved VAST video, tablet and location targeting support
- OpenRTB 2.2 provided improved PMP and non-intentional traffic support
- OpenRTB 2.3 provided support for native ads
- OpenRTB 2.4 introduced the digital audio advertising medium to the protocol
- OpenRTB 2.5 focused on updates in programmatic transactions through improvements in real-time interactions and notices
- OpenRTB 2.6 provides increased support for CTV ads
Glossary of Common RTB Terms
This glossary includes terms and abbreviations that are frequently used in conjunction with RTB concepts.
| DSP | Demand Side Platform. A system that allows buyers of digital advertising inventory to manage multiple ad exchange and data platform accounts through one interface. |
| HTTP | Hypertext Transfer Protocol. The protocol used for communication over a computer network and the most commonly used protocol for the internet. HTTPS is the secure version of HTTP. |
| IAB | Interactive Advertising Bureau. The organization which empowers the media and marketing industries to excel in the digital economy. |
| Impression | A term that refers to the point in which an ad is viewed once by a visitor, or displayed once on a web page. |
| JSON | JavaScript Object Notation. A minimal, readable format for structuring data. It is used primarily to transmit data between a web server and web client, as an alternative to XML. |
| PMP | Private MarketPlace. An invite-only marketplace where high caliber publishers offer their ad inventory to a selected group of advertisers. |
| Protobuf | Protocol Buffers. A method of serializing structured data. It is useful in developing programs to communicate with each other over a wire or for storing data. |
| Protocol | A standard set of rules that allow electronic devices to communicate with each other. |
| RTB | Real-time bidding. A method of advertising inventory which is bought and sold on a per-impression basis, via programmatic instantaneous auction, similar to financial markets. |
| SSP | Supply Side Platform. A system that allows web publishers and digital out-of-home media owners to manage their advertising space inventory, fill it with ads, and receive revenue. This term is largely synonymous with "Exchange". |
| VAST | Video Ad Serving Template. A document format that gives video players information about which ad to play, how the ad should display, how long it should play, and whether users are able to skip it, among other values. |
| XML | Short for eXtensible Markup Language. XML is a markup language like HTML. XML is designed to store and transport data. |