Real-time bidding

Real-time bidding (RTB) is a means by which advertising inventory is bought and sold on a per-impression basis, via instantaneous programmatic auction, similar to financial markets.

[8] According to UK's DPA, the ICO, report, companies involved in RTB "were collecting and trading information such as race, sexuality, health status or political affiliation" without consent from affected users.

"[10] In 2019, 12 NGOs complained about RTB to a range of regulators in the Union,[11] leading to a decision in February 2022 where the Belgian Data Protection Authority found a range of illegality in aspects of a system used to authorise much of RTB in the EU under the GDPR, the Transparency and Consent Framework produced by the Interactive Advertising Bureau Europe.

This triggers a bid request that can include various pieces of data such as the user's demographic information, browsing history, location, and the page being loaded.

[4] The primary distinction between an ad network and a DSP is that DSPs have the technology to determine the value of an individual impression in real time (less than 100 milliseconds) based on what is known about a user's history.

[18] This is due to technical limitations that continue to make the type of targeting and tracking available on the desktop essentially impossible on smartphones and tablets.

The lack of a universal cookie alternative for mobile web browsing also limits the growth and feasibility of programmatic ad buying.