What is Ad Exchange?

An ad exchange is a digital marketplace where ad impressions are bought and sold through real-time auctions, connecting supply-side platforms (publishers) with demand-side platforms (advertisers). Each time content loads, the exchange auctions the available ad slot to the highest qualified bidder in milliseconds.

Exchanges are the neutral middle layer of programmatic advertising: SSPs send available impressions in, DSPs send bids back, and the exchange clears the transaction.

Advertisers don’t use exchanges directly — their buying platform handles it — but understanding the chain (advertiser → DSP → exchange → SSP → publisher) explains where media dollars go and why supply-path transparency matters.