Which entity acts as a broker between a publisher and advertiser, using real-time bidding technology?

An ad exchange serves as a marketplace where publishers and advertisers come together, leveraging real-time bidding (RTB) technology to facilitate the buying and selling of advertising space. In this digital environment, publishers offer their ad inventory through the exchange, while advertisers can place bids based on their targeting criteria and willingness to pay for that inventory.

Real-time bidding allows advertisers to compete for impressions in an instantaneous auction, significantly optimizing both the purchasing process for ads and the revenue generation for publishers. This efficient mechanism means that as soon as a user visits a site, available ad spaces can be filled with targeted ads selected in real-time, based on the highest bid from participating advertisers.

The other options, while related to the digital advertising ecosystem, do not function in the same capacity as an ad exchange. An ad network aggregates ad inventory and connects advertisers to it, but it does not facilitate real-time bidding as directly as an exchange does. A third-party ad server is responsible for serving ads and tracking their performance, but it does not act as a broker in the bidding process. Lastly, a trafficker manages the delivery of ads but does not operate as a marketplace for bidding between publishers and advertisers.