Ad exchange
An ad exchange is the digital marketplace where advertising inventory is bought and sold in real time, impression by impression, through automated auctions.
It works like a stock exchange: publishers offer their ad space through an SSP and advertisers bid for it from a DSP. Every time a page or an app loads, the ad exchange runs an auction in milliseconds and the winning ad is shown to the user.
It is the core of programmatic buying. The price is not set in advance; it depends on how much each buyer values that specific impression, and that is where audience data makes the difference. An advertiser who knows who is behind an impression can bid more for the ones that matter and skip the rest.
