Bid request

A bid request is the OpenRTB message an exchange sends to bidders for one ad opportunity, describing the impression or impressions for sale, the site or app, the device, what is known about the user, the regulatory flags, the supply chain and the auction rules, including the time limit for a response.

The top-level BidRequest object (OpenRTB 2.6, section 3.2.1) carries id, one or more imp objects, exactly one of site, app or dooh, plus device, user, regs, source, the auction type at, tmax and currency and category constraints (OpenRTB 2.6). Each imp describes one placement with its format objects (banner, video, audio, native), floor (bidfloor, bidfloorcur), private marketplace rules (pmp) and the ssai flag.

The bid request is also where privacy and provenance travel. regs.gdpr flags GDPR applicability, regs.gpp carries the Global Privacy Platform string, user.consent carries the TCF consent string, user.eids carries identifiers such as UID2 or clean-room IDs with their inserter and matcher, and source.schain records every seller in the path (OpenRTB 2.6, sections 3.2.3, 3.2.20, 3.2.25, 3.2.27). A DSP's first engineering task is deciding which of these fields to parse, which to validate and which to ignore; the volume at which it must do so is the QPS problem.

Example: see the annotated request under OpenRTB. A field-by-field walk-through is in RTB architecture explained.

Related: bid response, OpenRTB, timeout, consent string, SupplyChain object.

Source: IAB Tech Lab, OpenRTB 2.6, section 3.2.

1. OpenRTB 2.6, sections 3.2.3, 3.2.20, 3.2.25, 3.2.27