Explain the Programmatic Ad Ecosystem: Publishers, SSPs, DSPs, Exchanges and RTB

You are interviewing for a product manager role at EMX, and the interviewer asks you to explain what programmatic advertising is. Describe the parties on the buying and selling sides and what each one does, then walk through how a single ad impression is bought and shown when someone opens a web page. ```hint Follow one impression Pick one page view and trace its ad slot from the moment the page starts loading until an ad appears. Ask who offers the slot, who decides whether to bid and how much, who runs the auction, and how long all of that is allowed to take. ``` ### Clarifying Questions - Should I focus on open-auction real-time bidding, or also cover private marketplaces and programmatic guaranteed deals? - Which channels are in scope: desktop and mobile web display, in-app ads, or video and connected TV as well? - Is the interviewer looking for a high-level overview, or for request-level mechanics such as bid requests, floor prices and timeouts? ### What a Strong Answer Covers - A definition that contrasts automated, impression-by-impression buying with manually negotiated insertion orders. - The main parties (publisher, advertiser or agency, supply-side platform, ad exchange, demand-side platform, audience data providers) and the job each does. - A step-by-step account of a real-time bidding auction for one impression, including the time budget it runs under and how the clearing price is set. - The deal types beyond the open auction and why buyers or sellers choose them. - The ecosystem's open problems, such as fraud, brand safety, intermediary fees and privacy limits on user data. ### Follow-up Questions - Much of the industry moved from second-price to first-price auctions. Why did that happen, and how did it change the way buyers bid? - With third-party cookies blocked in several browsers, how does a demand-side platform still decide what an impression is worth? - If you were the product manager for an ad exchange, which metrics would tell you whether the marketplace is healthy for both publishers and buyers?