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:

• AppLovin (which recently acquired MoPub)
• FreeWheel (owned by Comcast)
• Google Ad Manager (also known as Google Authorized Buyers, formerly known as AdX, and now part of Google Ad Manager)
• InMobi
• Magnite Inc (formed by the combination of Rubicon Project, SpotX, and Telaria)
• OpenX (company)
• Pubmatic
• Smaato
• Xandr (formerly AT&T AdWorks which bought AppNexus, now owned by Microsoft)
• Yahoo (formerly AOL, Brightroll, OATH and other entities rolled into the Yahoo brand)

• Demand-side platform
• Online advertising
• Supply-side platform
• Header bidding