Third-party exchanges rely on which buying method?

Third-party exchanges primarily rely on the open auction buying method. In an open auction, also known as a real-time bidding (RTB) auction, ad impressions are sold to the highest bidder in real-time. This method allows multiple advertisers to bid simultaneously for available ad inventory, maximizing competition and efficiency for publishers. Private auctions are invitation-only and involve a select group of buyers, offering more control but less scale than open auctions. Fixed auctions are not a standard term in programmatic advertising; pricing is typically negotiated or determined by dynamic bidding, not a fixed auction model.