First-Price Auction

In a first-price auction, the winning bidder pays exactly the amount they bid. This is the dominant auction model in programmatic advertising since the industry-wide shift in 2019 from second-price to first-price auctions. First-price auctions encourage buyers to bid their true value but can lead to overpayment if bidders don't have sufficient bid shading strategies. The shift aimed to increase transparency and reduce bid manipulation.