Ad Exchange

An ad exchange is the digital marketplace where ad impressions are bought and sold in real time. Publishers, usually through a supply-side platform, offer each available impression; buyers, through demand-side platforms, submit bids; and the exchange runs the auction and returns the winning creative, all in a fraction of a second.

For app marketers, exchanges are the main route to in-app inventory beyond any single network. Different exchanges carry different publishers, formats and price levels, so a DSP connected to several exchanges can compare sources and move budget to the ones that deliver the best users. Ask any partner which exchanges they buy through and whether you can see results by each — that visibility is the starting point for supply path optimization and for spotting low-quality sources early.

In everyday UA work you rarely interact with an exchange directly; you see it as a dimension in reporting, which is exactly where it earns its keep.