DSP Demand Side Platform

A Demand-Side Platform (DSP) is software that programmatically purchases digital ad inventory on behalf of advertisers. When a user visits a website, that publisher's SSP (Supply-Side Platform) sends a bid request to multiple DSPs: "User ID X, on page Y, in category Z—who wants to buy this impression?" DSPs evaluate the bid request, look up user profiles, run ML models to predict conversion probability, calculate a bid price, and respond within 100ms. The highest bid wins the impression. Ad is displayed, user sees campaign, advertiser hopes for a click or conversion.