RTB is the auction mechanism that sells individual ad impressions in the milliseconds while a page or app loads — each impression evaluated and priced separately, per user, per context.
Definition
When inventory becomes available, an ad request flows to exchanges; bidders evaluate the impression (context, user signals, predicted value) and respond with bids inside roughly 100 milliseconds; the winner's ad renders. OpenRTB standardized the plumbing. RTB's per-impression logic is also the intellectual ancestor of platform smart bidding — the same idea, absorbed into the walled gardens' own auctions.
Why it matters
RTB established the premise the whole modern stack rests on: every impression has its own value, and machines price it better than rate cards. Knowing where RTB ends and platform-internal auctions begin also clarifies vendor claims — a tool 'bidding' on Google or Meta is really setting inputs to the platform's own auction, not participating in open RTB.
In agentic execution
Adlyse's agents work at the layer above any auction: deciding goals, budgets, and structures that the auctions — RTB or walled-garden — then execute against, with humans approving each change.
Related terms
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