An ad exchange is a technology platform that facilitates the buying and selling of media advertising inventory from multiple ad networks.
[1] Prices for the inventory are determined through real-time bidding (RTB).
The approach is technology-driven as opposed to the historical approach of negotiating price on media inventory.
This represents a field beyond ad networks as defined by the Interactive Advertising Bureau (IAB),[2] and by advertising trade publications.
Notable ad exchanges include: