RTB

Detailed explanation

RTB, or Real-Time Bidding, is the auction mechanism at the core of programmatic advertising. When a user loads a page or opens an app with an available ad slot, that single impression is offered up for auction; multiple advertisers' demand-side platforms (DSPs) evaluate the opportunity based on data about the user and context, submit bids, and the winning bid's ad is served — all of this happens in the time it takes the page to render, typically under 100 milliseconds.

What makes RTB powerful is that it prices and targets every impression individually rather than in bulk. An advertiser can bid higher for a user who matches a valuable audience segment and skip or bid low on an impression that does not, which is a very different model from buying a fixed block of inventory regardless of who sees it. This is the mechanism behind most display, video, and native programmatic buying today, connecting advertiser DSPs to publisher SSPs and ad exchanges.

RTB's efficiency comes with trade-offs that media buyers need to manage: bid density and competition can push up costs on desirable audiences, and the automated nature of the auction makes brand safety, viewability, and fraud controls essential parts of any RTB strategy rather than optional extras.