Programmatic · also called bid stream, bidstream data
Bidstream
The bidstream is the continuous flow of bid requests and responses exchanged in real-time bidding, and the data they carry about sites, apps, devices, locations and users.
Every time an ad auction happens, a bid request is broadcast to many buyers. Across the whole market, that adds up to hundreds of billions of messages a day: the bidstream. Each message can contain the page or app, approximate or precise location, device type, IP address, user agent, user IDs and consent signals.
The bidstream is valuable. DSPs use it to decide bids, and it feeds analytics, contextual targeting and fraud detection. But it is also controversial. Because bid requests go to many companies, including ones that never win, critics and privacy regulators argue that broadcasting personal data this way can violate laws such as GDPR. Investigations have also shown bidstream location data ending up with data brokers.
The industry responses include consent frameworks such as IAB TCF and IAB Global Privacy Platform, data minimization in bid requests, and newer approaches such as seller-defined audiences and clean-room matching that reduce what is broadcast. For fraud analysts, anomalies in bidstream data (impossible device combinations, spoofed domains) are key signals.
Think of it like this
The bidstream is like a never-ending radio broadcast of lot descriptions to every auction house at once: useful for bidders, but everyone listening hears the details.
An example
A single news page view in France produces 60 bid requests to 40 companies, each containing the page URL, device model, coarse location and a TCF consent string.
Related terms
Bid request
A bid request is the message an SSP or exchange sends to potential buyers describing an available ad impression, inviting them to bid on it in a real-time auction.
Real-time bidding (RTB)
Real-time bidding (RTB) is an automated auction in which advertisers bid on a single ad impression in the fraction of a second while a web page, app or stream is loading.
GDPR
The GDPR (General Data Protection Regulation) is the European Union's data protection law, applying since May 2018, which governs how organisations collect and use personal data about people in the EU.
Data minimization
Data minimization is the privacy principle that organisations should collect and keep only the personal data that is adequate, relevant and necessary for a specific, stated purpose.
Pre-bid filtering
Pre-bid filtering is checking each ad opportunity for invalid traffic, fraud or brand-safety risk before a buyer bids on it, so bad impressions are avoided rather than refunded later.